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Slag as Raw Material in Cement Manufacture Bibliography of Selected Publications PCA Library Bibliography Series no. 18 (LB18)

The publications listed below address the use of slag, a by-product primarily of iron and steel operations, as raw material in cement production. While slag can also be interground with the clinker or added to the finished cement to produce blended cements, these applications are not the focus here. The references below include journal articles, conference papers, reports, and patents found in the PCA Library collection or identified through online database searches.

Abdel Kader, A.A.; Didamony, H.; Maky, A.K.T.; Tabl, M.E., “Burnability of cement raw mix containing B.F. slag,” Key Engineering Materials, v. 206-213, no. III, 2001, p. 1875-1878. (Presented at the 7th Conference and Exhibition of the European Ceramic Society, 2001, Brugge, Belgium). The use of mineralizers such as CaF2 and others in cement production increases savings in energy and fuel. Investigations have been conducted on the utilization of waste products such as granulated blast furnace slag. Burnability and clinker phase formation studies have been carried out on different raw mixes of kiln feed with different doses of CaF2. Also raw mixes containing different doses of G.B.F. slag up to 10% were investigated. All mixes were ignited up to l400 degree(s) C at different soaking times. The mineralizing effect of G.B.F.slag as well as CaF was studied by the determination of insoluble residue and free lime contents. The phase composition of the fired mixes was identified by the aid of XRD technique. 6 Refs.

Ahluwalia S.C.; Page C.H., “Effect of low grade fuels, combustible wastes and non-traditional raw materials,” 9th International Congress on the Chemistry of Cement, New Delhi, 1992. Volume 1. Congress Reports. New Delhi: National Council for Cement and Building Materials, 1992, p. 83-122. Depletion in the resources of good grade raw materials and the urgent need to conserve these has made it imperative to find ways and means of utilizing low grade raw materials, industrial and agricultural wastes and waste fuels. Research has demonstrated the feasibility of using a large number of low grade materials and industrial waste such as lime bearing carbonate sludges from paper, sugar and fertilizer industries, Ca(OH)2 from acetylene plants, slags from iron, steel and other allied industries, flyash from coal based thermal power stations, red mud and C2S waste from aluminum industry etc. as alternate and substitute raw materials with specific technical advantages in some cases. Despite considerable efforts to find technical and technological solutions to the problems of utilization, their actual use has remained limited primarily because of problems related to collection, handling, storage, transportation and the cost involved. Recycling of hazardous and non-hazardous wastes fuels in cement manufacture has been a very promising development in past two decades. With significant progress in design engineering and construction of waste derived fuel facilities. Although the use of wastes as raw materials of alternate energy sources in the manufacture of cement can result in significant saving and conservation of non-renewable materials, there is a need for comprehensive technical and management services in the area of utilization of wastes to make their use cost effective.

Ampadu, K.O.; Torii, K.; Kubota, T., “Chloride induced corrosion of steel bars embedded in ecocement-blast-furnace slag mortars,” Seventh CANMET/ACI International Conference on Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete, Chennai, Madras (India), 22-27 Jul 2001 (SP 199-39) American Concrete Institute. The New Energy and Industrial Technology Development Organization of Japan has developed a new type of hydraulic cement using incinerator ashes as part of the raw material. The process for making ecocement is similar to that of normal portland cement, but the raw material includes up to 50 per cent incinerator ash. The added benefit of this product is that it addresses the problem of ash disposal in Japan. The two types of ecocement are rapid hardening ECO-I with high chloride content, and

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portland cement type ECO-II with low chloride content. This study examined the effect of the blast furnace on the corrosive behavior of steel bars embedded in mortars made from the two types of ecocement. Mortar specimens were prepared with mild steel and stainless steel bars and were then exposed to severe saline conditions. The corrosion was electro-chemically measured and chloride concentration profiles were determined after specific exposure periods. The study demonstrated the beneficial effect of slag on the initiation of corrosion and the degree of corrosion of the steel bars. The chloride binding and microstructure was shown to have improved in both ecocements. The chlorides in ECO-I formed calcium chloro-aluminate, while the chlorides in ECO-II vaporized in the sintering process and combined with alkalis. This paper also described the half-cell potential and linear polarization resistance, the physical measurements and the linear polarization resistance and corrosion current. Calcium hydroxide content and hydration products were also described along with weight loss and corroded areas. 5 refs.

Batra, V. K.; Mittal, P. K., “Modernization of Kalyanpur Cement's Banjari plant (India),” World Cement, v. 25, no. 5, 1994, p. 63-66. Article describes conversion of this wet plant with total installed capacity of 0.4 mil tpy to the dry process. The project includes replacement of the three kilns with a single large 1650 tpd dry process kiln with preheater and calciner. Manufacturing 0.98 mil tpy of portland blast furnace slag cement is sought. Modernizing the plant involves installation of high-pressure grinding rolls for raw materials, slag and clinker, with high efficiency separators in close circuit and installation of a PC-based control system for interface integration. Slag is ground to 2800 Blaine, whereas clinker is ground to 4000 Blaine in two 2 stages. A nine-channel XRF spectrometer is used to analyze raw meal, clinker, and cement samples to ensure quality.

Beretka, J.; de Vito, B.; Santoro, L.; Sherman, N.; Valenti, G. L., “Utilization of industrial wastes and by-products for the synthesis of special cements,” Resources, Conservation and Recycling, v. 9, no. 3, Oct. 1993, p. 179-190. Experiments were carried out to synthesize calcium sulfoaluminate, calcium silicate and calcium sulfate from industrial process wastes such as fly ash, slag and gypsum. The raw materials were mixed together in the required stoichiometric ratios, ground, slurried, dried and fired in an electric furnace., A temperature of 1235 degrees C was needed for the production of calcium sulfoaluminate; at 1000 degree C the yield was low, with unreacted material and by-products present., Binary systems containing both calcium sulfoaluminate and silicate could be produced at 1100 degree C and above, but the simultaneous synthesis of the ternary system containing calcium sulfate as well was not possible because a sulfosilicate formed instead of calcium silicate.

Beretka, J.; de Vito, B.; Santoro, L.; Sherman, N.; Valenti, G. L., “Hydraulic behaviour of calcium sulphoaluminate-based cements derived from industrial process wastes,” Cement and Concrete Research, v. 23, no. 5, 1993, p. 1205-1214. The manufacture of cements based on calcium sulphoaluminate requires lower firing temperatures and lower grinding energy compared to ordinary portland cements (OPC). Some of these low-energy cements can be formulated in order to develop high early strength and other performances similar to OPC. Further interest in these types of cements relies on the possibility of using industrial process wastes as raw materials for their manufacture. It was found that a number of industrial wastes and by-products such as phosphogypsum, bauxite fines, fly ash and blast furnace slag can be employed without negatively affecting the hydraulic behavior of cements of planned C4A3S:beta-C2S:CS weight ratio 1.5:1:1. Blast furnace slag and fly ash can also be advantageously used as blending components of the fired products. 17 refs.

Bernshtein V.; Zdorov A.; Babich M. “Replacing clay raw material component by slags, ashes and sands,” Proceedings: European seminar on improved technologies for the rational use of energy in the cement industry, Berlin, 26-28 October 1992. Bad Homburg, GOPA Consultants, 1992, p. 453-455. The most promising trend in energy efficiency is the use of industrial by-products and industrial wastes in raw mix composition. Not only does it offer pollution control, but a reduction in the use of quarry and other natural resources. Investigations have shown that the most unfavorable raw mix

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component is high-aluminate clay – a common component in dry-process technology. Its tendency to selective agglomeration inevitably leads to decrease of raw mix reactivity under conditions of solid phase sintering when the size of component to be coated is of decisive effect on clinker formation kinetics. The authors’ early works carried out at Lipetsk cement plant, where high-aluminate clay was substituted by granulated blast furnace slag, resulted in 5-8 MPa increase of portland cement clinker activity and 10-12% decrease of fuel consumption for its burning.

Bhatty, Javed I.; Gajda, John, “Alternative materials,” World Cement, v. 35, no. 12, Dec. 2004, p. 41-48. The use of several alternative materials derived from industrial wastes and byproducts in the manufacture of Portland cement is discussed. Materials identified as raw material components in cement manufacture include marginal limestone, lime-bearing carbonates, sludges, metallurgical slags, flyash, bottom ash, desulfurization sludge from coal-fired power plants, and foundry sand. The composition of these materials must be compatible with those of the raw materials they replace in the cement raw mix. The cement industry has successfully made use of these nontraditional materials in applications such as clinkering to conserve thermal energy and improve production.

Birat, J.P.; Delbecq, J.M.; Hess, E.; Huin, D., “Slag, steel and greenhouse gases; Laitiers, acier et gaz a effet de serre,” Revue de Metallurgie (Paris); Presentation at the IISI Techno-32 meeting, Kyoto (Japan), 2000, no. 1, 1002. A steel mill is a logistical hub, where iron units by-products and effluents such as CO2 compete in terms of volume. The problem of greenhouse gas emissions will probably strengthen these transversal relationships. For example, blast furnace slag, which is a prime secondary material for the cement industry, substitutes for CO2-intensive raw materials such as limestone and bypasses the energy-intensive high temperature rotary kiln that is necessary to produce cement from virgin natural resources. If one is willing to view the steel mill as a co-producer of steel and slag, then one sees clearly why the greenhouse gas emissions should be shared among the two products. This is by no means an artificial viewpoint, as large reductions in emissions can be achieved by using slag as an additive to cement. The paper proposes a quantitative analysis of this issue of importance for the future. (authors)

Cerjan-Stefanovic, S.; Rastovcan-Mioc, A.; Novosel-Radovic, V.J., “Mechanical properties of cement with addition of electric furnace slag,” Metalurgija/Metallurgy, v. 36, no. 2, Apr-Jun 1997, p. 93-98. Blast furnace slag is the most commonly used secondary raw material in the production of cement. By abandoning the operation of blast furnaces in Croatia, deposits of slag have been reduced. The growth of electric furnace slag depots near steelworks and foundries calls for careful examination of that material in order to develop solutions for its use. The paper examines phase composition and morphology of average samples of electric furnace slag and separated fractions and mechanical properties of cement with addition of 15% of average sample of electric furnace slag and separated fractions. The examinations have shown that it is possible to use electric furnace stag as admixture to cement. 11 Refs. (In English)

Changhua, Li, “The effect and principle of industrial wastes used in wet rotary kiln,” Proceedings of the 3rd Beijing International Symposium on Cement and Concrete, Oct. 27-30, 1993, v. 2, p. 636-640. Using industrial wastes to produce cement clinker is a new field of research in the cement industry, which not only can reduce environmental pollution by reusing wastes, but also is an important way for developing new resources of raw materials of cement. The cement plant has wet rotary kilns with a capacity of 850,000 tons of cement per year. To improve profitability, we have developed the technology to use industrial wastes as raw materials and mineralizers to produce cement clinker. After several years of industrial tests, the clay material in raw meal has gradually been changed from common natural clay, i.e. sandstone, red clay, to a combination material, mainly phosphoric slag, copper waste and fly ash. The effect and principle of using industrial wastes to prepare cement raw materials are introduced and briefly evaluated.

Chatterjee, A.K., “Steel slags in cement-making : the current status of development,” Third CANMET/ACI International Symposium on Sustainable Development of Cement and Concrete, San Francisco, CA, 16-19 Sep 2001 (ACI Special Publication SP-202) Natural Resources Canada, Ottawa,

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ON, CANMET Energy Technology Centre, 2002. Two different types of slags are generated during the production of iron and steel. The first is blast-furnace slag, which is derived when iron is extracted, and the second is steel slag, which is generated when iron is converted to steel. Blast-furnace slag is often used as a supplementary cementitious material in the cement and concrete industry, but there is little known use for steel slag. An extensive survey of literature and patents has been conducted to try to find an economical use for steel slag in cement-making. The material has been characterized in detail, particularly based on steel slags available in India. Steel slags are generated in a basic oxygen furnace (BOF) or in a Linz-Donawitz (LD) converter or an electric arc furnace (EAF). Pilot scale studies have been conducted to determine the potential use of steel slag as a raw material in the production of portland cement clinker and also for the production of special cements such as calcium sulphoaluminoferrite cement. The study describes the development and formulation of blended cements that maximize the use of steel slag. This paper describes the mineralogical characteristics of LD steel slags. X-ray diffractometer traces of two LD slag samples showed the presence of dicalcium silicate, dicalcium and monocalcium ferrites. The paper also describes the physical characteristics of LD slags, hydraulic reactivity of LD steel slag and the cement formulations with LD steel slags. In particular, the paper focuses on the suitability of steel slags as a blending material with normal portland cement. Alkali-activated steel slag cements can be prepared by combining ground granulated slag with alkaline chemicals in liquid form or intergrinding slag with less hygroscopic alkaline chemicals. Steel slags can be used as a raw material for clinkerisation. It was concluded that there is potential use of steel slag for greenhouse gas reduction and environmental improvement and that technological options should be given special attention in terms of reducing global carbon dioxide emissions into the atmosphere. 27 refs.

Davidson, R.; Nexhip, C.; Norgate, T.; Sanetsis, S.; Washington, B., “'Dry granulation of slags for producing cement binder,” Australasian Institute of Mining and Metallurgy Publication Series no. 2, 2004, p. 85-96. (Presented at Green Processing 2004: 2nd International Conference on the Sustainable Processing of Minerals, May 2004, Fremantle, Australia.) Global cement production accounts for about five per cent of man-made CO2 emissions (WBCSD, 2002). Such operating practices will increasingly be considered unsustainable, unless significant reductions in environmental impact can be realized by the industry. Slag is a high volume waste product from ironmaking, with about 300 kg of slag being produced per ton of iron. Critically, one ton of slag waste, if used as a replacement feedstock for Ordinary Portland cement (OPC), can prevent around one ton of emitted CO2 since no calcining is required. Slag cement blends can also show superior properties compared to OPC, such as lower heats of hydration and higher late strengths, but more development is needed to overcome their low early strengths. Rapid quenching of molten slag is required to produce 'hydraulically-active' binder when reacting with OPC; but water quenching can also require between five to ten tons of water per ton of slag at the plant. 'Dry' granulation (atomisation) is emerging as an alternative technology, the resulting solid product does not require drying, and possibilities exist for recovering heat energy from the hot slag. CSIRO Minerals has well-developed skills and equipment in pilot-scale pyrometallurgical treatment, and granulation of molten slag, including traditional wet, and also dry methods. Techno-economic desktop studies can also be used to help quantify factors such as value-adding of treated waste products, potential reductions in CO2 emissions and carbon credits, reductions in water consumption, and the possible decreased energy costs associated with fine grinding of dry slag granulate. The authors present preliminary results from slag atomisation/dry granulation testwork (0.5 - 2.5 kg scale) and associated modelling studies, conducted using a 'synthetic' and industrial ironmaking slag. Outcomes from a techno-economic study on production of cement utilizing wet or dry atomised slag granulate will also be discussed in detail. 32 Refs.

Davis, M.; Engeln, I.; Harzt, T., “Experience with the Polysius roller mill for granulated blastfurnace slag at St. Lawrence Cement,” ZKG International, v. 56, no. 3, 2003, p. 50-54. The reduction in the use of raw materials and the problems of CO2 emissions mean that granulated blastfurnace slag is becoming increasingly important as a main constituent of cement. Increasing use has been made of roller mills to grind the blastfurnace slags as efficiently and economically as possible. Because of the successful results achieved with roller mills installed for blastfurnace slag in

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Korea and France, the operators of St. Lawrence Cement in Camden, New Jersey, decided to use a roller mill for grinding blastfurnace slag; it was commissioned successfully in 2001. Experience so far confirms that finenesses of 6000 Blaine and higher can be achieved with the result that "Grade 120" blastfurnace slag meals can be produced.

Didamony, H.; Abdel, Kader AA; Maky, AKT; Tabl, M. E., “Burnability of cement raw mix containing BF Slag,” Euro Ceramics VII, Pt. 3, Trans Tech Publications, Switzerland, 2002, p. 1875-1878. The wide use of mineralizers such as CaF2 and others in cement technology ensures power and fuel saving. Investigations were conducted for utilization of a waste product such as granulated blast furnace slag. Burnability and clinker phase formation studies were carried out on different raw mixes of kiln feed with different doses of CaF2. Raw mixes containing different doses of GBF slag up to 10% were also investigated. All mixes were ignited up to 1400 C at different soaking times. The mineralizing effect of GBF slag as well as CaF2 was studied by the determination of insoluble residue and free lime contents. Also, the phase composition of the fired mixes was identified by XRD. 5 refs.

Edlinger, Alfred, Method of producing an additive for mixed cements and device for carrying out said method. Patent no. 02070423 WO. Publication date: Sept. 12, 2002. The invention relates to a method of producing an additive for mixed cements that have good early strength. To this end, raw material is selected from a group comprising building rubble, waste glass, argil, marl, waste fireproof material, flue ash from power stations, waste pyrolysates, slags from non-ferrous industry and steel production, asbestos cement or asbestos sheets or fibers, harbor sludge excavated material from mines, alkali-containing clinker furnace bypass dusts and/or washing sludge from gravel extraction are melted in a melting cyclone and are then subjected to granulation, thereby producing a vitreous product. (In German)

Ellicott, G., “Mining the slag heap,” Ind. Miner, no. 427, no. 67, 2003, p. 64-65. Slags are produced in vast quantities as a by-product of the metallurgical industry. Three major types can be identified, namely blast furnace, basic oxygen steelmaking (BOS) and electric arc furnace (EAF) slags. About 16.5m tons of slag were produced and sold in the US in 2002, of which some 65% was blast furnace slag, while Europe produces about 40m tons per annum. The end uses and consumption of slag are discussed. About half is used in concrete for road surfaces. Other uses include mineral wool (an insulating material), railway ballast, and water and sewage treatment. Statistics are presented on the consumption of air-cooled blast furnace slag and steel slag in the USA in 2001. The largest provider of slag management services in the world is Heckett MultiServ, based in the USA and the UK.

Hamada, Takao, “Recycling of steelmaking slags and its recent status,”Kagaku Sochi, v. 38, no. 7, July 1996, p. 50-55. A review with 8 refs. on classification into blastfurnace slags and steelmaking slags, and their composition, characteristics, and recycling. Industrial application of the slags to cement clinker raw materials, rock wools, concrete aggregates, civil engineering, fertilizers, soil amendment, and foundation improvement are described. Recent research on recycling of the slags by new applications such as seawater pollution by red tide and sediment contamination is also briefly described. (In Japanese)

Helmy, I. M., “Utilization of some waste products as a mineralizers in the formation of portland cement clinker,” Industrial Ceramics, v. 23, no. 1, January-April 2003, p. 41-45. Portland cement clinker is a hydraulic material that consists of at least two-thirds by mass of calcium silicates (beta-C2S, C3S), the remainder containing C3A and C4AF. The aim of the present work is to study the utilization of by-pass cement dust, phosphogypsum and granulated slag as mineralizers in the formation of portland cement clinker. Mixes with various proportions of the mineralizers and cement raw meal were fired at 1200 degrees, 1300 degrees and 1400 degrees C for two hours then sudden cooled in the atmospheric air. The kinetics of formation were studied by the determination of the free lime and insoluble residue of the fired samples. The formation of the clinker was also investigated by XRD technique. The results of free lime and insoluble residue contents show the presence of high amount of free lime for samples fired at 1200 C, then decreases with firing

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temperature up to 1400 degrees C. Samples fired at 1400 degrees C show complete disappearance of free lime and less than 1.40% insoluble residue, therefore the clinker is completely formed. It was found that the slag is the most suitable mineralizer for the formation of portland cement clinker. The by-pass cement dust increases the formation of alite in the clinker due to the increase of high CaO content in the dust. Also, phosphogypsum acted as mineralizer in the formation of portland cement clinker. 16 Refs.

Hogan, Frank; Meusel, Jerry; Spellman, Lou, “Breathing easier with blast furnace slag,” Cement Americas, July/Aug. 2001, p. 11-15. The use of blast furnace slag is growing in popularity thanks to well-promoted environmental and energy-related benefits. In the United States, the production and marketing of ground granulated blast furnace slag (GGBFS) has seen extraordinary growth since its introduction in 1982. Used as a partial replacement for portland cement, this byproduct of the steel industry can significantly improve the durability of ordinary portland cement concrete and, at the same time, have a positive impact on the environment. This article enumerates the enhanced properties of concrete utilizing granulated blast furnace slag and the environmental benefits derived from its use. There are presently more than a dozen plants in the United States producing GGBFS with an estimated capacity of more than 2.5 million tpy, with more facilities in the planning or construction phase.

Hyun, Jong Yeong; Kim, Hyung Seok; Cho, Dong Sung, “Physical characteristics of E.A.F. steel-making slag,” Journal of the Korean Institute of Resources Recycling, v. 5, no. 3, 1996, p. 17-23. The slag discharged from the E.A.F. Steel-making company I, contains approximately 21% iron. 8% of the iron is recovered from the slag by hand-picking and magnetic separations. 13% of the unrecovered iron from slag is discarded or used for roadbed and reclamation utilization. While most of the unrecovered iron is in a simple state of metal, a small portion of the iron is in a combined state with alkaline earths element. The unrecovered and discarded iron can, therefore, be recovered by a crushing separation technique and magnetic separation. Since the major components of the slag consists of FeO, CaO, SiO2 , MgO and MnO, the slag can be used as a flux for the steel-making industry using scrap iron as raw materials. The slag can be used as heavy aggregates for construction because the specific gravity of the slag is higher than that of ordinary aggregates. For aggregates, the slag needs a long aging period. The non-metallic slag (metal-removed slag) can be used as the raw material for cement. The reutilizing of both metallic and non-metallic slag requires the precise control of grain size and components with respect to using purpose of the slag. 5 refs. (In Korean)

Iizuka, S., “Utilization of industrial waste and by-products by cement factories,” Seramikkusu (Japan), v. 27, no. 11, 1992, p. 1061-1065. This paper describes the present situation of the cement industry that has accepted and utilized wastes and by-products from other industries. Main utilized wastes are blast furnace slag from the iron industry, coal ash from coal-fired power plants, gypsum produced by flue gas desulfurization, waste tires, and so on. Since blast furnace slag contains much CaO and SiO2 which are main components of cement, about 15 million tons/year are used as cement material. Fly ash as fine powder and ash clinker generated from the bottom of coal combustion furnaces are both regarded as coal ash from power plants, and about 2 million ton of them are used as raw materials in a year. Gypsum is added to cement as coagulation modifier during cement clinker grinding. Waste tires are put into cement kilns as heating fuel and burned completely at high temperature in kilns. Because the kilns are unable to use large quantities of waste tires at a time, they are used as auxiliary fuel. 6 refs. (In Japanese)

Jochens, P. R., Wolhuter, C. W., and Howat, D. D., “Utilisation of slags for manufacture of cement. Rapid technique for assessment of characteristics of raw materials,” Journal of the South African Institute of Minerals and Metals, v. 69, no. 4, Nov. 1968, p. 217-228. Use of milled granulated blast furnace slag for cement is already well-established in South African building and civil engineering industry but little information is currently available regarding suitability for this purpose of slags from electric arc furnace smelting in ferrochromium industry; rapid method, based upon use of micro DTA, for investigation of composition modifications required to make such slags acceptable as construction cements has therefore been investigated; the

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investigation indicates that experimental procedure provides a promising procedure for the study of such slags. 13 refs.

Kikuchi, Ryunosuke, “Recycling of municipal solid waste for cement production: pilot-scale test for transforming incineration ash pf solid waste into cement clinker,” Resources, Conservation and Recycling, v. 31, 2001, p. 137-147. Incineration ash of municipal solid waste accounts for a great portion of the matter in landfills, and minimization of resource consumption and recycling of waste are important factors for ensuring the future welfare of humankind. The study presented in this paper reports a technology for producing cement from incineration ash of municipal solid waste, incineration ash of sewage sludge and other wastes such as aluminum dross and copper slag. As incineration ash of municipal solid waste contains chlorine, special attention should be paid to fixing the chlorine within the cement. It was verified that proper treatment (formation of calcium-chloroaluminate) is capable of fixing the chlorine. In order to confirm the efficacy of this technology before it is used on an industrial scale, a pilot-scale test (50 tons/day) was conducted. The quality of the resulting cement is sufficient to enable the cement to be put to practical use. Furthermore, the tested process does not cause secondary pollution. Consequently, 50% of raw materials for cement production can be obtained from incineration ash of municipal solid waste.

Kurdowski, W.; Wieja, K., “Belite cement with increased brownmillerite content,” Cem.-Wapno-Gips, v. 45, no. 2, 1992, p. 45-50. (In Polish) The article describes the use of waste slag from Cu melting and blast-furnace dust as raw material for the preparation of a series of belite clinkers and cements with increased brownmillerite content. Differences in hydration source in the initial period are found. XRD confirms differences in monosulfate and ettringite contents of pastes. Sample microhardness is 7- 13 MPa after 3 days of hardening and 8- 35 MPa after 28 days.

Lee, Kun-Mo; Park, Pil-Ju, “Estimation of the environmental credit for the recycling of granulated blast furnace slag based on LCA,” Resources, Conservation and Recycling, v. 44, no. 2, May 2005, p. 139-151. The objective of this research was to quantify the environmental credit for granulated blast furnace slag (GBFS) recycling, and then to propose a recycling option best suited for the maximization of the environmental credit. The most appropriate method for the quantification of the environmental credit resulting from the recycling of byproducts is the system expansion method. The system expansion method was applied to the recycling of GBFS from the iron and steel manufacturing process for the quantification of its environmental credit. GBFS has been recycled as raw material for portland cement, slag cement, slag powder and silicate fertilizer. Environmental credit of each recycling application was calculated from three different perspectives: life cycle inventory on CO2, characterized impact on global warming, and weighted impact of the product system based on the Eco-indicator 99 method. Maximum environmental credit of the GBFS recycling occurs when recycled to raw materials for slag cement and Portland cement.

Lin, Zongshou; Huang, Yun; Liu, Jinjun; Zhao, Qian; Mi, Chunyan, Manufacture of steel slag cement swelling agent and expansive cement. Patent no. 1322689. Assignee, Wuhan Yisheng Science & Technology Co., Ltd., 8 pp. The swelling agent is manufactured by milling the steel slag to sp. surface area of 300-450 m2/kg. The expansive cement is manufactured by mixing 70-85 wt.% portland cement with 15-30 wt.% swelling agent. The title agent can reduce the cement production cost and environmental pollution.

Lohnherr, L.; Menzel, K., “Operating experience with the production of slag cements in a roller mill,” ZKG International, v. 52, no. 3, 1999, p. 136-146. When clinker and blastfurnace slag are interground in a ball mill the blastfurnace slag with its poorer grindability is less finely ground, but trials in a semi-industrial Polysius roller mill have shown that when this grinding system is used for intergrinding, the clinker and blastfurnace slag are ground to approximately the same fineness. Portland slag cements with low proportions of blastfurnace slag can therefore be produced very efficiently with Polysius roller mills. From earlier investigations it is

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known that finer grinding of the slag fraction is very advantageous for the strength development of a blastfurnace cement, while a more finely ground clinker in the mix brings little advantage. Finer grinding of the blastfurnace slag is therefore a suitable way of making full use of its latent-hydraulic properties, especially for blastfurnace cements with high proportions of slag. When clinker and blastfurnace slag are interground to high levels of fineness the clinker fraction is unnecessarily overground, so in this case separate grinding is an advantage. Mills fitted with double rollers are also advantageous for separate grinding of blastfurnace slag to high levels of fineness because of their outstanding drying properties. In the first example, which comes from the Bernburg cement works, blastfurnace slag is ground and dried in a roller mill designed for producing raw meal and then combined with the clinker meal in the closed circuit of a combined grinding plant. The second example deals with a Korean blastfurnace slag grinding plant, and shows how blastfurnace slag meal can be produced economically in a roller mill at low energy consumption with finenesses corresponding to a specific surface area of up to 5 300 Blaine. 4 refs.

Maroto F.P.; Moreno T.V., “Use of blast-furnace slag as raw mix in the obtaining of cement and the modification of its phases with manganese. Hydration reactions,” Informes de la Construccion, v. 39, no. 392, November/December 1987, p. 77-81. A study of the reactive behavior and suitability for cooking of raw mixes made with crystallized blast furnace slag, limestone and Fe2O3 after being submitted to various thermal treatments. The reactivity of said raw mixes was shown to be good at temperatures superior to 1,350 degrees C, producing traditional clinker materials of Portland cement. In addition, the suitability for cooking of raw mixes made with crystallized blast-furnace slag was shown to be far superior to traditional ones supplemented with limestone, clay and modulus modifiers. The effect of manganese on the clinkerization process was determined. The presence of an elevated Mn content causes an important alteration of the mineralogical composition of the clinker obtained. In addition, the solid solubility limit of manganese in the C3S, C2S, C3A, C2F, and C4AF phases was established, while solubility formulae are proposed in which the oxidation states of manganese formulae are established. Finally, a study was carried out on the hydration process of cements obtained from raw mixes made with crystallized blast-furnace slag as well as on those with a high manganese content. It was found that the former undergoes a hydration in the early stages similar to that of traditional portland cement (P-450). The latter, those with a high Mn content, develop an ettringite phase more quickly. (In Spanish with English summary)

Mayes, G., “A revolutionary synergy—steel manufacturing by-products in cement production,” PCA Fall Technical Session, September 2000, Oak Brook, Ill. TXI’s CemStarSM process is described, including the factors that led to its development, the economic and environmental benefits, and the technology itself. Since TXI owns both a steel plant and cement plant in close proximity, research and experimentation involving the two operations made sense. A typical system consists of a material hopper, belt conveyors, a weigh feeder, and a tipping valve or gate feeder arrangement. Kiln feed chemistry must be adjusted to compensate for the iron, aluminum, silica and calcium in the steel slag added to the kiln. This calculated mix design determines the extent to which the product can be added to a particular kiln. Benefits include 5-15% increase in clinker production, fuel savings, emissions reductions, and reduction of natural resources.

Monshi, A.; Asgarani, M. K., “Producing portland cement from iron and steel slags and limestone,” Cement and Concrete Research, v. 29, no. 9, 1999, p. 1373-1377. The slags from blast furnace (iron making ) and converter (steel making) after magnetic separation are mixed with limestone of six different compositions. The ground materials are fired in a pilot plant scale rotary kiln to 1350 °C for 1 hr. The clinker is cooled, crushed, mixed with 3% gypsum, and ground to fineness of more than 3300 cm2/g. Initial and final setting times, consistency of standard paste, soundness, free CaO, and compressive and fractural strengths after 3, 7, and 28 days are measured. Samples with higher lime saturation factor developed higher C3S content and better mechanical properties. Blending 10% extra iron slag to a cement composed of 49% iron slag, 43%

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calcined lime, and 8% steel slag kept the compressive strength of concrete above standard values for type I ordinary Portland cement.

Morioka, Minoru; Maeda, Yoshitaka; Sakai, Etsuo; Matsushita, Hiromichi, “Study on 32.5N/mm2 grade cement using slowly cooled blast furnace slag and granulated blast furnace slag,” Concrete Research and Technology, v. 15, no. 2, May 2004, p. 78-88. The 32.5N/mm2 grade cement (325 cement) using slowly cooled blast furnace slag and granulated blast furnace slag has a tendency toward small fluidity change over time compared with the 325 cement prepared with the ordinary portland cement (OPC) and limestone powder (LSP). On the other hand, it has a long setting time and is slow in developing early age strength. This improved when high early strength cement was substituted. Benefits include reduced carbon discharge compared with using limestone, as well as the reuse of byproducts. (In Japanese; English summary.)

Nakano, T.; Kanatsu, T.; Inoue, K., “Assessment of adaptability of coal gasification slag to fine aggregates for concrete and raw material for manufacture of cement,” Denryoku Doboku (Electric Power Civil Engineering), no. 266, 1996, p. 71-79. Entrained bed integrated coal gasification combined cycle power generation (IGCC) has higher heat efficiency and better environmental benefits than the conventional pulverized coal firing thermal generation systems, hence its practical use is anticipated. In the entrained bed gasification furnace, the nucleus of this new power generation system, ashes in coal are melt, then quenched into the water and discharged as glassy solidified slag and its amount reaches 60-110 thousand tons per annum at an IGCC plant of 500MW class, hence the firm establishment of its effective utilization measure has become a major issue from the viewpoint of facilitation of practical use of IGCC. In this study, adaptability of coal gasification slag to aggregates and raw material for manufacture of cement are described. As a result of a series of experimental studies with the objective of firm establishment of effective utilization measures of the above slag, it has been found that the slag concerned is a glassy solidified body different from flyashes in terms of its form, but has the same quality as flyashes chemically and is adequate for an admixture for concrete, fine aggregates and raw material for cement. 11 refs. (In Japanese)

Oates, David Bridson; Cail, Kevin Moire; Lehoux, Paul Honore; Ungar, Robert Kim; Hopkins, Donald Stephen; Cross, James Edward; Ritch, Michael, Enhancement of cement clinker yield by feeding a fused particulate fly ash or slag. Patent no. US 6391105 B1 20020521, US 2001-785705. Assignee: Lafarge Canada Inc. 7 pp. The yield of cement clinker recovered from a kiln assembly is enhanced by feeding a particulate material comprising silica and an oxide of at least one of Ca and Al, for example, fly ash, into contact with hot cement clinker. The fly ash melts to a partially fused material which chemically reacts with the hot clinker to produce a pyro-processed cement clinker of cryst. hydraulic silicates. The blast furnace slag, steelmaking slag, nonferrous slag, and silica fume may also be used as the particulate material. The extruder is added to the hot cement clinker downstream of the formation of the cement clinker, and suitably is added to the hot cement clinker at the upstream end of the cooler of the kiln assembly, or within the kiln, downstream of the burning zone, and more esp. in the initial cooling zone at the discharge end of the kiln

Oner, M.; Erdogdu, K.; Gunlu, A., “Effect of components fineness on strength of blast furnace slag cement,” Cement and Concrete Research, v. 33, no. 4, April 2003, p. 463-469. The strength development of 1:1 mixes of clinker and blast furnace slag with varying fineness of components from 3000 to 6000 cm2/g was studied. Overall results indicate that, in manufacturing blast furnace slag cement (BFSC), it is not only the fineness of the clinker-slag mix but also that of the individual components which govern the choice of the mix composition for a desired strength. In manufacturing BFSC, grinding clinker component to a higher fineness should be practiced, as it is more effective in regulating the strength and it is also more cost-effective. Cost effectiveness should be further investigated in more detail for the final choice of the mix composition, preferably with varying slag additions. 7 refs.

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Palou, M. T.; Majling, J., “Preparation of the high iron sulphoaluminate-belite cements from raw mixtures incorporating industrial wastes,” Ceramics-Silikaty, v. 39, no. 2, 1995, p. 63-67. High iron sulphoaluminate belites were synthesised using different kinds of raw components, which were, however, equal in chemical composition with respect to CaO, SiO2, Al2O3, Fe2O3 and SO3. A blast furnace slag, two kinds of brown muds and two kinds of fly ashes were used as waste raw components and limestone and bauxite as the natural raw components. Pure gypsum and gibbsite were used as the additional raw components. Raw mixture compositions were calculated by a specially designed computer program. The phase compositions of the product clinkers were determined by XRD. The cements were also compared on the basis of their compressive strength and calorimetric rate of heat liberation methods at an early stage of hydration. Although only partial conclusions can be drawn from the results as to the role of individual components for clinker preparation, the mechanical strength of specimens (28 days compressive strength in the range of 33 to 54 MPa) justifies the use of the specified wastes for the preparation of high iron sulphoaluminate belite cement clinkers. 13 refs. (In English)

Patzelt, N., “Finish grinding of slag,” World Cement, v. 24, no. 10, 1993, p. 51-58. Due to its latent hydraulic properties, granulated blast-furnace slag has been used for many years as an important constituent of blast-furnace cement. Generally, slag cement is manufactured by compound grinding of components in the required proportions. Compared with co-grinding, separate grinding of granulated blast-furnace slag has many advantages. Being able to freely select the product parameters eliminates leftovers from the previous grinding material when changing products, and fewer silos are then necessary. Because drying is carried out separately, damage to the SO3 carrier is ruled out. Modern plants for separate grinding of slag employ tube mills, tube mills with high-pressure grinding rolls, high-pressure grinding rolls, and roller mills. Grinding plants in England, Germany and Taiwan are described, and the different grinding systems used are compared. Because of their compact design, roller mills offer the best conditions for grinding granulated blast-furnace slag; however, the product quality cannot be variably adjusted, and the particle size distribution is steep. The combi grinding process is employed when existing tube mills are available, or when quality considerations demand that blast-furnace cements also have to be ground in the same plant. It requires the highest capital expenditure, however.

Perkins, David; Renfrew, Scott, “Utilization of steel slag in a California cement plant,” Conference Record – IEEE-IAS/PCA 2004 Cement Industry Technical Conference, Chattanooga, TN, April 25-30, 2004, p. 111-119. A cement production facility in the coastal California area utilizes a patented process to introduce steel slag directly into the feed end of the kiln. Steel slag shares many common characteristics of the cement feedstock and chemically combines with the entire mix. Not a raw material; it has already been heated to 3000 degrees Fahrenheit, and having a chemical composition quite similar to Portland cement clinker, the raw mill feed is proportioned to a chemical composition that will result in the correct clinker chemistry. This paper highlights plant production achievements, quality control and operational challenges associated with the usage of slag in clinker production. This paper also discusses theories of NOx and CO2 emission reductions per unit clinker produced, in addition to an overview of the slag handling and feeding system design and implementation process at the plant.

Piniecki, Ronald, Method for cement clinker production using vitrified slag, Patent no. 06740157. Publication date May 25, 2004. Patent assignee: Lone Star Industries, Inc. A method for the production of cement clinker comprises the introduction of vitrified slag into the feedstock stream prior to the clinkering zone. The addition of vitrified slag can increase the clinker output rates and/or reduce the energy requirements for maintaining the kiln temperatures. In one embodiment, the vitrified slag is a vitrified blast furnace slag. A stream of feedstock material containing lime is introduced into the feed end of the kiln; providing a vitrified slag with the stream of feedstock material into the clinkering zone; and conveying the vitrified slag and feedstock material through the clinkering zone.

Poeschl, Franz, Process for manufacture of structural cement. Patent no. DE 3633176 A1 880407. Patent assignee: Loesche GmbH. Publication date April 7, 1988.

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In the manufacture of structural cement by preliminary grinding of the clinkers and additives, grinding to final fineness in a drum mill, optionally with additives, and sieving out the final product, the raw materials and additives are preground together in a roller mill to a coarse, free-flowing material which is subjected to a 1st sifting prior to the grinding in the drum mill. Moist additives, such as pozzolans or slags, are dried in the roller mill. The pregrinding is adjustable to give particles ranging from coarse to cement grade fineness after the 1st sifting, i.e. the 1st sifting may result in all or part of the particles being of final cement quality while any grit is sent to the drum mill or to the 2nd sifting stage. The process saves energy, is flexible, results in a higher throughput, and has a more controlled effect on the grain structure of the product. (In German)

Puertas, F.; Blanco-Varela, M.A.; Palomo, A.; Vazquez, T., “Reactivity and burnability of raw mixes made with crystallized blastfurnace slags. Part 1,” Zement Kalk Gips, v. 41, no. 8, Aug. 1988, p. 398-402. The burner behavior of raw mixes made with crystallized blast-furnace slags, limestone and Fe2O3 was studied by x-ray diffraction and optical microscropy. The raw mixes contained the limestone with grain sizes smaller than 125 micrometers and the slag in different grain size fractions. At temperatures up to 1300°C the raw mixes showed a medium reactivity, so that when the slag grains were bigger than 45 micrometers, the gehlenite (C2AS) from the slag remained unreacted. Above 1350°C the reactivity of the raw mixes was good, producing the normal phases of the Portland cement clinker. At 1350°C the amount of the liquid phase decreased with increasing grain size of the slag. With slag grains smaller than 90 micrometers and with burning at 1450°C, the obtained clinkers had a normal mineralogical composition and distribution of the clinker phase.

Puertas, F.; Blanco-Varela, M.A.; Palomo, A.; Vazquez, T., “Reactivity and burnability of raw mixes made with crystallized blastfurnace slags. Part 2,” Zement Kalk Gips, v. 41, no. 12, Dec. 1988, p. 628-631. The burnability of raw mixes made from crystallized blast-furnace slag, limestone and Fe2O3, at temperatures of 1350°C, 1400°C and 1450°C, was evaluated. When the slag grains are smaller than 63 micrometers, the burnability of the raw mix at 1350° is very good, as at this temperature more than 90% of the CaO was combined. The factor in the equation of Miller to estimate the burnability at 1400°C representing the influence of the grain size of clay materials bigger than 435 micrometers on the free CaO content of the clinker was determined. In raw mixes made with crystallized blast furnace slag, this coefficient is about 80% lower when the slag has a grain size between 32 and 90 micrometers. When the grains are bigger than 90 micrometers this coefficient is about 32% lower than indicated by Miller. In the raw mixes with staged granulometric distribution, burnability is better in respect to the big grains, fundamentally due to a better distribution of the intersticial phase.

Ramesohl, Hubert; Meyer, Hans Wilhelm, Production of cement clinker with slags, pozzolans, and trass as cement aggregates, Patent no. US 2002174806. Patent assignee: KHD Humboldt Wedag AG, Germany. (In German) The cement clinker is manufactured from raw meal, which is pre-heated in a heat exchanger conduit passed by the waste gas from a rotary kiln, if needed pre-calcined in a pre-calcining step, and fired to obtain cement clinker in the sintering step of the rotary kiln, thereafter the cement clinker is cooled. The production of cement clinker, esp. cement with addition of a cement aggregates, e.g. slag, which is milled in a circulation crushing plant to manufacture cement-fine slag powder is carried out by utilization of excess slag capacity in the cement clinker production. Thereby a middle-grained slag fraction is removed from a 3-fraction visual app. as raw material and fed into the material inlet of the rotary kiln included in the cement clinker production. The chemical composition of the remaining raw material components is coordinated with the additional material of the middle-grained slag fraction.

Ramesohl, Hubert; Meyer, Hans-Wilhelm. Method and installation for production of cement clinker. Patent no. 20020174806 A1. In the production of cement clinker or cement with the addition of a cement additive, such as slag, which is ground in a closed-circuit grinding installation into slag meal of equal fineness to cement, in order to utilize excess slag capacity in a beneficial way in the cement clinker production process, an

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intermediate slag fraction withdrawn from a three-fraction classifying device is added as a raw material component to the stock inlet of the rotary kiln of the cement clinker production line, and at the same time the chemical composition of the remaining raw material components is adapted to the added quantity of the intermediate slag fraction.

Rastovcan-Mioc, Alenka; Cerjan-Stefanovic, Stefica; Novosel-Radovic, Vjera, “Mechanical properties of cement with addition of blast furnace slag,” Metalurgija/Metallurgy, v. 37, no. 1, Jan-Mar 1998, p. 21-26. Blast furnace slag is the most commonly used secondary raw material in the production of cement. The chemical and phase compositions of blast furnace slag were examined. A two-hour heat treatment of blast furnace slag at 200, 400, 600, 800, and 1000 degree C will show the influence of temperature upon physical and mechanical properties of cement when such slag is added. 12 Refs.

Renfrew, S.; Perkins, D., “Utilization of Steel Slag in a California Cement Plant,” IEEE IAS PCA Cement Industry Technical Conference, 46th 2004, p. 111-120. RMC’s Davenport, California plant utilizes a patented process to introduce steel slag directly into the feed end of the kiln. Steel slag shares many common characteristics of the cement feedstock and chemically combines with the entire mix. Not a raw material; it has already been heated to 3000 degrees Fahrenheit, and having a chemical composition quite similar to portland cement clinker, the raw mill feed is proportioned to a chemical composition that will result in the correct clinker chemistry. This paper highlights plant production achievements, quality control and operational challenges associated with the usage of slag in clinker production. This paper also discusses theories of NOx and CO2 emission reductions per unit clinker produced, in addition to an overview of the slag handling and feeding system design and implementation process at the plant. Since 2002, the plant has maintained a slag utilization rate of approximately 7 percent clinker. Clinker and slag compositions may allow up to 13 percent utilization rates. The goal is to maximize slag addition, continue increased fuel efficiencies per tons clinker produced, and limit the amount of costly raw mix additives.

Rostock, Martin, “Granulated blastfurnace slag from the blast furnace into the cement silo: an example,” ZKG International, v. 57, no. 6, 2004, p. 68-77. Granulated blastfurnace slag has proved to be an attractive cement component already for a century. Processing granulated blastfurnace slag from EKO Stahl GmbH to cements at Rudersdorfer Zement GmbH is an example taken from current practice. Various raw material parameters are monitored. The requirements for cements have led to four process alternatives of granulated blastfurnace slag processing when optimizing the costs. The range comprises ten cements with a content of granulated blastfurnace slag of approx. 15 to 85%, among them cements with a low effective alkali content, a high sulphate resistance and low hydration heat. 13 Refs.

Sas, Laszlo; Szabo, Laszlo; Szarkandi, Janos, Additive mixture for cement clinker production and its use, Patent no. WO 03/045868 A1. Patent Assignee: Duna-Dráva Cement KFT. Publication date June 5, 2003. The invention relates to an additive mixture for cement clinker production, consisting of a mixture of slag formed in the course of producing pig-iron and steel and hydrocarbon based wastes deriving form mineral oil industry or materials containing such wastes, of a maximum grain size of 20 mm, in a quantity and proportion adaptable to the raw material matrix of cement clinker. Conditioning agents, for example packaging materials, wood favorably polluted sawdust or cuttings, paper or cardboard, may be added. The additive mixture is fed in the cement clinker burning furnace at the section of 1.050-1.150ºC and added to furnace flour of a temperature of 800-850ºC.

Schafer, Heinz-Ulrich, “Experiences in grinding of slag and additives on Loesche mills,” Cem.-Wapno-Beton, v. 3, no. 2, 1998, p. 48-55. Long experience in grinding of raw materials for clinker production has been utilized to apply Loesche mills for the production of ground granulated blast furnace slag, ordinary portland cement, slag cement and cement with interground additives. The newly developed 2+2/3+3 technology by Loesche combines well proven elements with high reliability in a new setup of different sized rollers and a high efficiency cage wheel type classifier, which allows fine grinding at high sp. surface without

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facing extensive vibrations. The good drying capability of roller mills allows the use of moist interground additives like granulated blast-furnace slag, trass, pozzolana and limestone. Water demand, strength development and the workability both of cement mortar and concrete made from cement produced in the Loesche mill are comparable or even better compared to those known from conventional ball mill systems.

Schafer, H.-U., “Loesche mills for the cement industry,” ZKG International, v. 56, no. 3, 2003, p. 56-62. The grinding systems of a cement plant still account for more than 50% of the total electric energy consumption of the plant. Moreover, in new plants they are responsible for a major portion of the total investment costs for mechanical equipment. No matter what material is to be ground, this situation means that grinding systems must be designed to ensure simple and rapid adaptation to market demands for new or different products. For raw material grinding plants, for instance, the "one kiln - one mill" concept is the trend for large kiln lines. In clinker and granulated blast furnace slag grinding, it is becoming more and more important for the grinding system to offer a high degree of flexibility. Petcoke and anthracite have become very important fuels for the cement industry as they are available in large quantities at a low price level. Grinding systems that produce the fuel for precalciner and kiln must be able to cope with the different comminution properties of anthracite, petcoke and all other kinds of solid fuels. This paper presents an overview of the different demands imposed on grinding systems for the range of feed material encountered in the cement industry. 10 Refs.

Taeb, A.; Faghihi, S., “Utilization of copper slag in the cement industry,” Zement Kalk Gips, v. 55, no. 4, April 2002, p. 98-100. The Sarcheshmeh copper complex belonging to Kerman is one of the biggest copper producers in Iran. Apart from the conventional copper products slag is obtained as a by-product in a quantity of about 1000 t/d. In the past this material was deposited as a waste material on a disposal site. The space for further dumping is limited and the slag causes environmental pollution so the utilization of this material in the production of cement was investigated. It has been found that if the copper slag is used as a component of the raw mixture the kiln output can be increased and the quality of the clinker improved.

Taylor-Smith, Ernest John; Phillips, Graham J., Portland cement manufacture from slag from the production of magnesium metal. U.S. Patent no. 06709509. Publication date: March 23, 2004. A process for the production of Portland cement and white Portland cement using magnesium furnace slag, a waste product from the manufacture of magnesium metal, as a primary starting material. The furnace slag is blended with calcium oxide and silicon dioxide to form a feedstock which is heated to a temperature and for an amount of time sufficient to form clinker. The clinker is cooled, ground to a powder, and blended the clinker with powdered gypsum to form the Portland cement. White Portland cement may be produced by removing iron containing compounds from the slag, minimizing contamination of the material by iron compounds throughout the process, and cooling the clinker in a manner that minimizes oxidation of any remaining iron compounds in the clinker.

Valkova, I. S.; Dogandzhieva, R. G., “Producing portland cement clinker using blast furnace barric- manganese slag,” 7th International Congress on the Chemistry of Cement, Editions Septima, Paris, v. 2, 1980, p. I:79-83. The investigations conducted show that slags containing basic oxides necessary to form portland cement clinker – CaO, Al2O3, SiO2, Fe2O3 and in some cases also alloying oxides BaO and Mn2O3 -- are valuable raw material for portland cement clinker. The high-temperature treatment at which the slags have been subjected permits the same to be equalized with the raw cement mixture at temperature 1000-1100 degrees C, i.e. when the interaction in the solid phase is already completed with formation low-basic clinker minerals. It is proved that the introducing of slags either in vitreous or in crystalline state intensifies clinker formation and at the same time the processes of lime saturation are accelerated and the formation of clinker minerals is relieved. The presence of BaO and MnO in the slag contributes to the increase and modification of alite crystals, which leads to increased strength values of the cement.

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Wang, Guiming; Xie, Junlin, “The research of slagging property about the coals used in cement industries,” Proceedings of the International Conference on Energy Conversion and Application (ICECA’2001), p. 797-800. This paper applies the method of experiment and investigation, measures the fusion point of the different burn-out behavior of pure coal samples mixed with cement raw material, and researches the mechanism of coal slagging. The relation between the liquid phase in the production of cement and slagging as well as burning property of different kinds of coal is studied. It can be a guide to the production-engineering problem of coherence and blockage inside cement linked pipe, wide selective range of control about coal, utilizing high inert coal. 3 Refs.

Watson, Robert C., Method for manufacturing cement using a raw material mix including finely ground steel slag, Patent no. 06491751. Publication date Dec. 10, 2002. Patent assignee: Texas Industries, Inc. A method is provided for manufacturing cement from a raw material mixture which includes finely ground steel slag. Selected quantities of steel slag and other raw materials are mixed with each other and supplied to a raw mill. The steel slag and other raw materials are preferably ground to a fine, dry powder. For some applications, the dry powder is preferably supplied to a blend tank for further mixing to ensure more uniform commingling of the finely ground steel slag with other finely ground raw materials. The fine dry powder may be supplied to a preheat system and then to the feed end of a kiln. Alternatively, the dry powder may be supplied directly to the feed end of a kiln.

Weigand, W.; Salter, J., “Use of shell gasifier slag as a cement raw feed,” Emerging Technologies Symposium on Cement and Concrete in the Global Environment, March 10, 1993, Portland Cement Association, 1993 (SP114). A number of new technologies have been developed in recent years to more efficiently and cleanly utilize the energy available in coal. One of these is coal-fired integrated gasification combined cycle (IGCC). This process produces a synthesis gas suitable for combustion in steam turbines for electrical production or as a feedstock for chemical production. The by-product of this process is a slag material which can be reused many different ways. Three examples are use as asphalt aggregate, concrete aggregate, and cement raw feed material. The slag is particularly attractive as a cement raw feed material because of the presence of alumina, silica, and iron oxides. This paper presents the results and a discussion of a test burn at a southern United States cement plant during August 1990. The slag was used as a supplement to the raw material feed during a Type II production burn. The production results, physical testing, and environmental testing results are presented of the finished product which passed all ASTM Type II requirements. The results of this test burn suggest that the slag material produced from this process is well suited as a cement raw feed material, especially when plant needs require an additional low cost source of iron oxide to supplement their present raw materials.

Wiedenhoft, Charles T.; Steuch, Hans, Method and apparatus for using metallurgical slag in cement clinker production. U.S. Patent no. 20030205175. Publication date Nov. 6, 2003. A method and apparatus for production of cement clinker uses fragmented metallurgical slag, such as from blast furnace production of iron or steel, introduced into a rotary kiln at an infeed located between the kiln front feed end and the rear outlet end. The metallurgical slag combines with predominantly limestone feedstock material flowing inwardly from the feed end toward a burner pipe at the outlet end and intimately blends with the limestone material to become transformed into cement clinker as the blended materials progress through the kiln. Preferably, the metallurgical slag is introduced into the kiln through a kiln dust infeed apparatus present in many rotary kilns at a mid location.

“A win-win situation,” World Cement, v. 35, no. 1, Jan. 2004, p. 65-67. Lafarge North America provides details of its South Chicago slag grinding facility which has entered into a mutually beneficial agreement with local steel manufacturer Ispat Inland. The deal saves Ispat Inland the cost of hauling and disposal of the slag, while Lafarge obtains a steady source of material that it processes into cement, while helping the environment by using less energy than a conventional cement kiln. The plant aims to reach a maximum capacity of 500 000 tpa by 2006.

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Yamanaka, R.; Toyama, S.; Kadoguchi, K.; Urakawa, Y., “Ground granulated blast furnace slag (concrete admixture),” R and D Kobe Seiko Giho (Research and Development, Kobe Steel Engineering Reports), v. 46, no. 3, 1996, p. 32-35. The Furukawa steel mill of Kobe Steel has had manufactured ground granulated blast furnace slag particulates (under a commercial name of K-ment) by using a ball mill. In 1993, the process was changed to using a vertical roller mill with better productivity, and the operation is continuing smoothly since then. This paper reports the summary of the K-ment facility, and manufacturing conditions of the K-ment to meet quality requirements thereon as a cement admixture. The steel mill has provided all of its blast furnaces with ground granulating facilities to obtain water granulated slag. The slag pulverized into finer particles is the K-ment. Raw materials (water granulated slag plus natural gypsum) fed into a vertical roller mill are crushed between the roller and a table, dried, and then adjusted in a classifying process. Discussions have been given on its strength properties, solidification time that results in fineness of the powder to meet quality requirements, properties of water granulated slag as the raw material, and effects of storage time periods. As a result of the discussions on these items, a manufacturing technology which can produce an admixture having better characteristics than conventional admixtures produced by ball mills was established. (In Japanese)

Yates, R.J.; Sankaranarayanan, R. Hatch, Perkins, D., “CemStar process and technology for lowering greenhouse gases and other emissions while increasing cement production,” Proceedings of the International Symposium on Ecomaterials and Ecoprocesses 2003, Vancouver, BC (Canada), 24-27 Aug 2003 ; Montreal, PQ, Metallurgical Society of the Canadian Institute of Mining, Metallurgy and Petroleum. This paper presents a cross-industry collaboration between the cement and steel industry. The cement industry contributes approximately 7 per cent of the world's carbon dioxide emissions. Texas Industries Inc. is a cement producer which has used a newly patented process in many of its cement kilns to reduce emissions of carbon dioxide and nitrogen oxides. In addition, the CemStar process reduces energy and refractory consumption while increasing cement and clinker production. The synergy-based process makes use of a low value waste by-product from the steel industry. Cement producers load air-cooled iron and steel slags directly into a kiln to increase Portland cement production in an environmentally sound manner. This paper describes the development of the process, which was first used in 1994 by Texas Industries Inc. It includes a process description for the slag and its conversion to clinker. The use of air-cooled slag allows the steel industry to keep capital and slag processing costs of a minimum while providing the cement industry with a raw material. Texas Industries has received awards for its efforts to reduce carbon dioxide emissions and for its positive effects on nitrogen oxide emissions. 10 refs.

Young, Rom D., Method and apparatus for using blast furnace slag in cement clinker production. U.S. Patent 5,494,515, Feb. 27, 1996. Assignee: Texas Industries, Inc. 15 p. A process and apparatus by which blast-furnace slag can be added to the feedstock materials fed into the feed-end of a rotary cement kiln to form cement clinkers. The blast-furnace slag is crushed and screened to provide blast-furnace slag particles having particles with a predominant size of up to a maximum diameter of substantially 2” or less.

Young, Rom D., “A method for using steel slag in cement clinker production,” Proceedings of the Twentieth International Conference on Cement Microscopy, Guadalajara, Mexico, April 19-23, 1998. A patented process (in the United States and 35 foreign countries) has been developed by which steel slag can be added to the feedstock materials fed into the feed end of a rotary cement kiln to form cement clinkers. The steel slag is crushed and screened to provide steel slag particles having a maximum diameter of 50 mm (2 inches).It has long been recognized that many of the chemical compounds in steel slag are common to cement chemical compounds, and because steel slag is available in large quantities geographically, it would be advantageous to be able to use steel slag in the cement-making process for the following reasons: 1. Production Increase; 2. Fuel Savings; 3. Quality; 4. Environmental benefits.

Yum, Gun Chang; Lee, Seung Kyou; Rho, Jae Sung, “The effects of the converter slag on the manufacturing process and property of cement,” Journal of the Korean Institute of Resources

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Recycling, v. 6, no. 4, 1997, p. 17-23. (In Korean) In cases of using converter slag as iron source for cement, it is investigated whether the addition of converter slag affects the burnability properties of mixed materials, the clinkerization and the physical properties of cement. As a result of addition of converter slag, the amount of quartz is increased, but the amount of clay is decreased. The content of r C3S and C4AF is increased, but that of C2S and C3 A is decreased. Mn2 O3 of the converter slag has a role of mineralizer and improves the burnability and clinkerization. Some of the Mn2 O3 exist in the intermediate compounds and in the calcium silicate. In case of using the converter slag as the raw material of the cement, it is cost effective in respect to the raw materials, the energy and the content of alkali in the clinker.

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