IntroductionHall-Buck Marine, Inc., maintains a long term lease ofthe Globalplex facility from the Port of South Louisianaand already handles a variety of products includinglimestone, fluorspar and wood chips. With cement importson the rise, the company developed an interest in a facilityupgrade to accommodate receipt of cement from oceangoing vessels and loading of barges for shipment up river.The resulting increased tonnage through the port andincreased employment will benefit both the Port of SouthLouisiana and HBM.

The goal was to obtain a long term contract to servea major cement company, and this required a state of theart facility. Results of a feasibility study and preliminaryengineering recommended a terminal storage capacity of100 000 t (Figure 1). Contracts were let to accomplish therecommended expansion. Some of the key componentsincluded a Siwertell ship unloader from BMH Marine,two 50 000 t capacity concrete domes from DOMTEC®international, and a mechanical automated reclaim systemfrom Cambelt International for withdrawal of cementfrom the domes.

BMH's Siwertell ship unloader will share the existingdock with two other loading/unloading machines. Thenew unloader is designed specifically for handling cement,but with minor modifications, can also accommodateother products. The Siwertell is flexible in the types ofproducts it can handle and in the size of vessels it canunload, ranging from small barges to 50 000 dwt oceangoing ships.

Construction of two 50 000 t capacity domes allowsthe operator to store two separate grades of cement, andalso ensures adequate space for each new 50 000 tshipment upon its arrival. Drive-in doorways and flatfloors allow access into cacti (ionic for maintenance orfinal clean tip for conversion to an alternate cement type.

The automated screw reclaimers for this project arcdesigned specifically for cement. However, with minimaladjustment, they can effectively handle other types ofproducts.Planning and designRiver Consulting Inc. completed the initial conceptualdesign following an evaluation of alternative storage andreclaiming systems. RCI was selected to complete theformal engineering design and provide constructionmanagement for the project. Responsibilities includedfinal design, specifications, equipment selection, shopdrawing review, budgets, schedules, division of workand overall construction supervision.

The ship unloaderThe ship unloader is a Siwertell, F-type machine (Figure 2). Thesesystems are known for theircontinuous and controlled productflow and environmentally friendlyoperation. The conveyors arecompletely enclosed from inlet tooutlet, virtually eliminating spillageand fugitive dust.

Figure 2. Siwertell F-type unloadersbipment from Sweden

The commodity, in this case,cement, is picked up at the bottomof the vertical screw by the inletdevice. The inlet device has a variableh y d r a u l i c s p e e d w h i c h i scontinuously, and automaticallyadjusted in order to maintain thesteady flow of material. From theinlet device, the cement is fed into avertical screw conveyor. This operatesthe horizontal screw, which feeds thegantry screw conveyor. Theconveyors and transfer points aretotally enclosed. High capacityunloading is achieved down to amaterial level of 100 - 150 min (4 -6 inches) before final clean up occurs.

The S iwer te l l i s h igh lymanoeuvrable in its abilitv to reachinto the ship's hold to pick up thecement. Its movements include:

• Travelling Mounted on rails, theship unloader can travel along thedock to reach the various holdswithout having to move the ship.

• Slewing The upper part of theunloader can rotate 280'.

• Luffing The horizontal boom can

be raised and lowered 25" fromhorizontal during unloading.During repositioning, it can beraised 45" for clearance of thehatch covers.

• Pendulum The vertical boom canbe kicked in and out 30 fromvertical.

The unloader is also equippedwith a reach extender, an articulatedscrew conveyor at the feeding endof the main vertical boom. Thismechanism provides additionalslewing and pendulum movementsindependent of the main verticalconveyor. This multitude of optionalmovements make it possible to reachcement in practically any corner ofthe ship's hold, including thosehidden by the deck and even throughnarrow hatches.

Although the basic functions ofthe F-type are the same as when itwas introduced in 1987, considerableimprovement has been made totoday's units, including manyaccessibility and ease of maintenancefeatures.

For example, today's models areequipped with a light weight, radioremote control which can also beoperated by cable as a safety backup.The PLC based control systems havebeen improved to offer many, morefunctions and options than oldersystems. The svstems can be tiedinto the terminal's central control.Some units are equipped with amodem, enabling BMH to performtrouble shooting and adjustprogramming without leaving theirhead office in Sweden.

The ship unloader was fullyassembled and tested prior to beingshipped from Sweden. Upon arrivalin Reserve, the transport ship willbe positioned parallel to the jetty andthe Siwertell will be lifted off theship and placed oil awaiting cranerails on the jetty. Only the finalperformance test will remain, whichoccurs while unloading the firstvessel of cement.

Dock to dome conveyingIn this installation, the Siwertelltransfers the cement onto acompletely enclosed belt conveyor,which is also able to handle productsother than cement, if necessary.BMH's cover belt lifter arrangement,a special type of enclosure, makespossible the transfer of cement fromunloader to belt conveyor withoutspillage or dust.

Cambelt's CamSpan Galleryconveyors (totally enclosed, largespan modules) provide longunsupported spans across theadjacent highway

Figure 3. Totally enclosedCamSpan conveyor gallery.

(Figure 3). These dust tight enclosuresassure total containment of conveyedmaterial. The mailbox shape of thegallery provides a flat floor on theinside, which facilitates cleanup ofspills or material buildup. Thestandard long span capability of 36in (120 ft) significantly reducesconveyor erection time and requiresfewer support bents and foundations.

The belt conveyor transportscement to a new transfer towerlocated between the two domes.Cement is discharged from the beltconveyor onto air slides to fill thedomes.

Concrete storage domesConcrete domes have proven to beeffective for storage of many bulkmaterials, including cement. Theprimary advantages of concretedomes include:• Superior protection of the stored

material.• Strength and durability.

• Low cost per t construction cost.• Excellent environmental control

and containment of dust.

• Rapid construction regardless ofweather.

Before construction of the domesbegan, a pile foundation was installedand a sub grade reclaim tunnel built.Given the soil conditions at theGlobalplex site and the anticipatedproduct load (100 000 t of cement),prestressed concrete piles 14 inchsquare by 110 ft long were drivenand capped with a 30 inch thickheavily reinforced concrete mat.

Construction equipment andreinforcement bars were nextstockpiled on the mat foundation,The dome shaped air form (singleply roofing fabric) was then attachedto the edge of the pile cap

and inflated (Figures 4 and 5). Once inflated to itshemispherical shape, polyurethane foam was sprayed tothe interior surface. Next, reinforcement bars were tiedin place as required by the structural engineer. SkilledDomtec® International nozzlemen sprayed shotcrete toembed the rebars and achieve the designed concretethickness.

Successful dome construction requires both properengineering and quality control of the constructionprocess. Domtec® International's structural consultingengineers are experienced in dome design, and technicianshave constructed many of the world's cement and flyash storage domes, including the two largest, each witha capacity of at least 60 000 t. Shotcreting a dome byspraying overhead against a flexible form is very differentfrom other sprayed concrete applications. An adequateskill level is critical to proper dome construction.

At Globalplex, the reinforcing requirements andshotcrete thickness were engineered to withstand theanticipated loads, including the pressure created bystacking cement approximately 80 ft high against thewalls.

As each dome neared completion, concrete curbswere placed at the top to accommodate a head houseand dust collector (Figure 6). Each dome also has a largedrive-in doorway, including a hydraulically operatedstructural steel door capable of withstanding the pressurefrom the stored cement.

The automated reclaim systemAutomated reclaiming systems have been installed inthe two 50 000 t storage domes. The Cambelt reclaimerallows the dome and its superior strength to be utilisedefficiently. The marriage of the dome and reclaimerprovide the following advantages at the Globalplex bulkhandling facility:

• Superior protection of stored materials.• Major cost savings compared to other storage and

reclaim systems.• Maximum utilisation of the storage space inside the

dome.• Virtually 100% reclaim of the stored materials.• High reclaim rates.• Reduced operating and maintenance costs.• No personnel working inside the dome - a major

safety feature.• Excellent environmental control.

The Cambelt reclaiming system consists of the followingcomponents (Figure 7):

• A mechanical load-in conveyor system.• A center column support base.• A rotating center column.• A support bridge and rotating screw reclaimer.• A cable hoist for raising and lowering the bridge.• An observation and maintenance platform.• Head house column drive equipment.• Controlled discharge and mechanical load-out.• Emergency discharge hoppers.

Automated reclaim of the cement is initiated by activatingthe fluidised bin bottom at the base of the rotating centrecolumn. During phase one of the reclaim cycle, cementflows to a rat hole by gravity without the use of thereclaim screw. During phase two, cement is reclaimedusing a combination

Figure 4. Outside veiw of air form inflation

Figure 5. Inside veiw of air form inflation

Figure 6. Dome construction nears completion.

Figure 7. Automated reclaiming system.

of gravity and screw reclaim (Figure10). Only during phase three does themechanical screw pull the remainingcement to the discharge. The reclaimercolumn support base is mounted inbeam pockets built into the tunnelwalls. on its top side, the support basecarries the entire load of the heavyreclaimer, while from below, it alsosupports the controlled dischargeequipment.

Rotation of the center column isachieved by a drive assembly locatedinside the head house at the top of thedome. The drive equipment includesa large gear box by Falk. The bridgetruss supports an open reclaimer screw(Figure 8). The bridge truss is attachedto the rotating center column with apin connection. The entire bridgescrew drive, and reclaim screw werefully assembled and aligned beforebeing disassembled for shipment.

Figure 8. Rotating centre columnwith reclaiming bridge andmaintenance platform

An observation and maintananceplatform was installed just below thehead house at the top of the rotatingcentre column. Access is through ahatchway in the drive assemblyplatform (head house floor).

A programmable logic controllerautomatically provides the requiredflow of material to the centredischarge. Sensors located throughoutthe system provide data to the PLC,which adjusts the column's rotationalspeed and the depth of the screw's cutinto the cement pile. The graphicalmanmachine interface softwareprovides a control system which iseasy to operate;

modem support is provided, includingthe capability for 24 hr per day, on-line training and trouble shooting(Figure 9).

Although the Cambelt reclaimeris designed to reclaim virtually 100%of the stored material, additionalemergency discharge openings aredesigned into each reclaim system asa precautionary maintenance feature.These allow partial reclaim by gravity,leading to access to the screw throughthe dome's large drive-in door.

Figure 10. Reclaiming phases.a) Phase 1 - gravity reclaiming.b) Phase 2 - gravity and screw

reclaiming.c) Phase 3 - screw reclaiming to

dome floor.

Pre-assembly of the steelstructures and preparation forinstallation of reclaim equipment tookplace outside during the finalconstruction of the storage domes.

During the design process, it wasconcluded that the Cambelt reclaimerprovided the most economical designafter consideration of capital cost andoperating cost.

Barge loadingThe barge loading system consists ofa 500 tph capacity 386 in (1267 ft)long belt conveyor connecting thedome reclaim system with the bargeloading station. Cement is loadedonto barges through a telescopingload out spout with dust controlequipment.

ConclusionThe new facilities at Globalplexprovide the Port of South Louisianaand HallBuck Marine with thecapacity for increased volume.Design of the complete facility, fromthe ship unloader to the concretedomes and back to the barge loadingstation, incorporates state of the artcomponents selected not only foreconomics but for their versatilityand proven track record of effectiveperformance in bulk cement.

The Globalplex cementterminal is now under longterm lease to Holnam Inc.

©Reprinted from World Cement "CementManufacturers' Case Studies" 1997.