how to taking samplings

7/28/2019 How to Taking Samplings

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Surveying JKSimMet Course - 2009

Transmin - Lima Srvy - 1

Comminution Plant

Surveys

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Delivering world class solutions

to the minerals industry

Why Survey?

Modern grinding circuits are monitoredcontinuously

Operators live with the plant all day, every day

With all this attention why do we need toconduct surveys?

Sampling and Surveying


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Why Survey? (cont..)

Surveys are required where

Plant improvements are under consideration

Reasons for problems are not obvious

A circuit simulation model is required

Response to an ore type must be defined

Benchmarking


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Definition of a Survey

To measure the operation of the plant undercontrolled conditions and for a specifiedinvestigative purpose

(as opposed to ongoing measurement forproduction accounting)



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Survey vs Production Accounting

Surveying

Aimed at defining plantoperation

Typically manual streamcutting

Samples subject to

unusual tests Samples must be inter-

relatable in short term

Accounting

Aimed at measuringproduction and losses

Often automated streamcutting

Standard tests applied

Samples must be inter-relatable in medium tolong term


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Survey vs Production Accounting

Surveying

Happens rarely

Needs to be plannedeach time

Accounting

Happens daily

Part of standardoperating procedures



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Collecting Good Samples I

Understand the circuit and its purpose

Understand the aim of the survey

Determine information required and the tests tobe carried out

Minimum sample mass is that required fortesting

Select streams to be sampled


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Collecting Good Samples II

Understand each stream that is to be sampled

Mass flow of solids and water

Particle size distribution

Stream geometry

Stream access

Sample site physical access

Other (temperature, viscosity, toxicity, etc)



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Collecting Good Samples III

Required sample mass will depend upon

Test mass requirements (as mentioned)

Particle size distribution, especially the top size

Physical realities

theoretical calculation can be performed usingthe equations of Gy (Ref)

typically for coarse particle streams Gy givesunrealistically larger sample sizes

rules of thumb and experience are often applied


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Mass Requirement Estimation

Calculation - Statistical Base

Simplest based on assumption ofPoisson probability distribution see next

slide More complex Hogg (1988)

Most complex Gy (1982)

Experience

J KTech

MPTech - UCT



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Simple Statistical EstimationSample Name: SAG Feed

Solids Density: 2.52 tonnes/m3

Required rel. error: 10.00 %

Sample size: 100.00 Kg

95% Confidence Range

Size Cumulative Kg Sample with 100.00 Kg sample

fraction % for < Cumumlative % Passing

(mm) Passing 10.00 % Low High

Rel. error

400.00 100.00

300.00 99.60 5956056.26 97.16 - 102.04

212.00 98.10 623858.67 95.14 - 101.06

150.00 96.30 182861.00 94.38 - 98.22

106.00 85.00 8754.70 82.36 - 87.64

75.00 74.80 3822.97 73.22 - 76.38

53.00 66.00 1911.70 65.04 - 66.96

26.50 52.30 735.59 51.37 - 53.23

13.20 43.30 551.65 42.77 - 43.83

9.50 39.80 523.51 39.60 - 40.00

6.30 34.50 506.30 34.20 - 34.804.80 31.60 504.46 31.44 - 31.76

3.40 26.00 502.00 25.69 - 26.31

2.40 20.50 501.60 20.19 - 20.81

1.70 16.60 501.49 16.38 - 16.82

1.20 12.50 501.41 12.27 - 12.73

0.90 9.70 501.39 9.54 - 9.86

0.60 7.40 501.38 7.27 - 7.53

0.40 5.50 501.38 5.39 - 5.61

0.30 3.60 501.37 3.49 - 3.71

0.00


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Mass Requirement Estimation

Estimates based on experience

J KTech, hundreds of plant surveys over 20 +

years Effectively particle number (volume) based

Based on typical ores with SG 2.7 to 3.0

mass recommendations will need correctionfor SG values significantly outside this range



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Experience Based EstimationLocation Topsize Recommended

Sample Mass

ROM 0.5 2m Not recommended, useimage analysis

PrimaryCrushed Ore

300mm 1500kg & supplementwith image analysis

Secondary

Crushed Ore

100mm 300kg

TertiaryCrushed Ore

30mm 60kg

Fine crushedOre

12mm 20kg


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Experience Based EstimationLocation Topsize Recommended

Sample Mass

SAG Disch.

with Pebbles

100mm 150-200 kg

SAG Disch 25mm 60kgCoarse BallMill Disch.

12mm 20kg

Fine Ball MillDisch.

3mm 10kg

Cyclone U/F 12mm 20kgCyclone O/F 1mm 2kg



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Screen Delimited Streams

Special case

Example -20mm + 10mm stream

Typical Screen Delimited Sizings

0

20

40

60

80

100

1 10 100

Size (mm)

CumulativeW

t%Passing


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Steep distribution curve

Important to determine proportions of oversize

and undersize Detection of holes and inefficiency

Sample size often determined by the need toknow about fines or to pinpoint top size

Mass requirements reduced - no fine fraction



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Location Topsize Bottomsize

RecommendedSample Mass

SAG Pebbles 80mm 12mm 100kg

Coarse 100mm 50mm 100kg

Medium 30mm 15mm 250kg

Fine 12mm 6mm 10kg


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Sample Collection

Belt Cuts for Conveyed samples,top size >30mm, stop belt and dig off.

Collect all from a 3 5 m section, and

Collect all +75 mm from a 15 20 msection

Box collectors for screen oversize samplestopsize


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Slurry Samples

The best results are obtained by takingcuts at regular intervals of time and byso using the cutter, that its operationapproaches that of a properly runmechanical sampler.

Taggart (1945)


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Slurry Sample Cutters

The cutter should be large enough so that

there is no danger of overflow while making

one passage through the stream of pulp. Theaperture should be at least four times the

diameter of the largest grain in the pulp; the

cutter should be smooth inside, watertight,

and designed to clean itself readily.Taggart (1945)



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Cutter Requirements

Manufactured to task

Many options

See Sampling High Throughput Grinding andFlotation Circuits Mosher and Alexander

Slot preferably 5 x maximum particle size Volume sufficient to fill maximum of 30% during

a single pass


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Typical Cutter Design

200mm

150mm

12mm

100mm

Length to suit

sampling point

150

mm

30mm

Radius80mm

(A1)

(B1)

(C)

(D)

(A 2)

(B2)

(B3)



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Image Analysis Blasted ore

Digital or conventional photographs ofmuckpiles or trucks as they dump at primarycrusher

Analyse with Split Desktop

Conveyed ore

Video for entire survey period Analyse with Split On-Line

Correct with measured fines from belt sample


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Survey Preparations

Plant personnel awareness

Metallurgists

Operators Maintenance

Process control

Management

Agreement, purpose, timing and opportunities



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Survey Preparations

Identify desired survey streams

Achieve mass balance

Define a process

Meet modelling needs

Establish feasibility of sampling desired streams

If yes choose cutters

If no, can it be yes or is stream required


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Survey Preparations

Design and acquire cutters

Buy

Build

Borrow

Test cutters

Check design (especially handles and slots)

Establish technique

Educate samplers

Check repeatability



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Survey Preparations

Identify equipment in the circuit

Mills

Cyclones

Screens

Crushers

Anything else? Identify equipment measurements required

What is needed to get the measurements


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Detailed Planning

Write a survey document

Survey goal(s)

Brief survey plan

Plant preparations required Survey timing

Detail the samples to be taken and how

Detail the equipment measurements to be takenand how

Detail other data to be collected



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Detailed Planning

survey document (cont)

Detail personnel requirements

Analyse the safety issues of sample collection andequipment measurement (in detail issue by issue,

J SAs may be required)

Detail post-survey sample handling and treatment

Detail costs involved

additional personnel, lab services, downtime


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Detailed Planning

Distribute survey document to all stakeholders

Discuss and refine document

Identify synergies Maintenance opportunities that match with Survey

related plant shutdowns

Opportunities for additional measurements

Training opportunities



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Detailed Planning

Clearly establish your own role

Control major survey processes

go / no go

plant stability monitor

data collection checker

troubleshooter


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Carry Out the Survey

Month to Week before

Ensure plant is configured as required

Identify survey time window

Ensure instruments are calibrated Check for operational stability issues

Ensure all cutters are tested and OK

Order cutters, shovels, bags, drums, lights, etc

Ensure lab is ready and aware

Establish sample ID method



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Carry Out the Survey Month to Week before

Prepare survey spreadsheet

brief survey description

list all samples

space for dates, times and ore sources

space for wet and dry weights

space for all data to be collectedspace for all machine measurements

preliminary calculations

checklist


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Day before

Label all sample bags, buckets and drums

Check all equipment

Measure available equipment

conveyor speeds

crusher gaps

installed motor powers

screen apertures

anything else?



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Day before (cont.)

establish operational aims with metallurgist,foreman, shift-boss and operators

establish night shift goals and communicate thesepersonally at the start of nightshift

the survey will be much easier if the plant is

nearly ready after night shift Confirm maintenance and control issues

personnel availability for equipment tag out

collection and capture of data


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Survey day

check operations and maintenance for issues

distribute samplers, survey equipment and

measurement tools to appropriate locations

establish 100% survey readiness

monitor plant condition

establish an adequate stability level

survey start



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Carry Out the Survey Survey day

signal for survey cuts to be taken (eg 15 minuteintervals)

Continue to monitor plant stability, ore changes,control actions

observe sampling if possible

check that manual data is being collectedcyclone pressure

cyclone numbers

Anything else?


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Survey day

stop survey sampling

call for plant shut down

call for equipment tag out sample from stopped conveyors

measure required equipment

check for 100% completion

de-tag equipment

clearly release plant back to operations



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Survey day

ensure any other data is collected (DCS, etc)

transport all samples to laboratory

weigh all samples wet and in containers

filter and dry all samples

weigh all dry samples

weigh all containers for tare weight

Important - survey in morning, samples all dried andweighed by days end


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Typical Plant SAG followed by discharge screen, recycle crusher,

2 x Ball mills and cyclones



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Survey Streams

1

3

4

5

6

9

7

8

2


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SAG Feed

1

1000tph ConveyorTop size =250mmBelt Cut

600 - 1500kg



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SAG Discharge

2X

1200tph Slurrytopsize=80mminaccessible


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SAG Pebbles

3

200tph ConveyorTop size =80mm80kgBelt Cut or Screen o/s



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Recycle Crusher Product

4

200tph ConveyorTop size =20mmBelt Cut 30kg


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SAG Screen U/S

51000tph slurryTop size =13mmInaccessible / Needs work

?



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Cyclone Feed

6

3500tph slurry (200tph/cyclone)Top size =13mm20kg solidsSlurry CutterBlank off 1 cyclone o/f and sample u/f


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Cyclone Underflow

7

2500tph slurryTop size =13mm20kg SolidsSlurry Cutter



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Ball Mill Discharge

8

2500tph slurryTop size =13mmSlurry Cutter20kg SolidsSpecial arrangement


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Ball Mill Discharge



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Cyclone Overflow

9

1000tph slurryTop size =1mm2kg SolidsSlurry Cutter


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Selected Samples

1

3

4

5

6

9

7

8

2X

?



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SAG Screen U/S

What can we do ?

Adjust equipment so we can measure !

Use mass balance

Relies on good quality samples of cyclone

feed and ball mill dischargeHas no redundant information


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