holman wilfley trial report final

8/12/2019 Holman Wilfley Trial Report Final

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WRAP MDD018/23 WEEE separationtechniques

Holman Wilfley wet shaking tabletrial report

AbstractThis report describes trials conducted with SGS Mineral Services on a Holman Wilfley WetShaking table for WRAP project MDD018/23. The aim of the project was to trial innovativetechniques to tackle some of the more difficult separations encountered by primary andsecondary WEEE processors. Recovering copper from mixed WEEE is a notoriously difficultseparation and several techniques have been tested during this project to attempt to find asolution to the problem.

The wet shaking table is a technique which originates from the mineral processing industriesand has been in use for many years. Its use in the recycling industry is a recent

development.The aim of this specific trial was to test the techniques ability to recover fine copper from acopper plastic mixture. Fine copper is often found in the WEEE plastic stream and therecovery of it from plastic is currently a problem for which there are no suitable solutions.

The copper-rich plastic mixture was pre-treated in two ways in order to size reduce thesample material. This allowed for an investigation into the effect of particle size on thesuccess of the separation to be carried out. One sample of the copper-rich plastic wasgranulated to a 5mm.Some of the copper-rich plastic material was left in its original condition at 8-12mm.

Each of the samples was processed on the wet shaking table, with the following conclusions.

The


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WRAP MDD018 WEEE Separation Techniques

Holman Wilfley Wet Shaking Table Trial Report

A wet shaking table capable of processing 1 tonne per hour of size reduced copper-richplastic from WEEE processing has an installed capital cost of 110,000 and a payback timeof nine months. Therefore this technique has good potential for use in the WEEE recyclingsector.

Table of contents Abstract.......................................................................................................................... 1

1.0 Information from Trial ........................................................................................... 6

1.1 Photograph of Trial Equipment ........................................................................... 6

1.2 Description of Trial Equipment ............................................................................ 7

1.3 Trial Objectives................................................................................................ 10

1.4 Sample Material ............................................................................................... 10

1.5 Trial Methodology ............................................................................................ 10

2.0 Trial 1 - less than 2.36mm granulated copper rich plastic ...................................... 12

2.1 Feed Material................................................................................................... 12

2.2 Results ............................................................................................................ 13

2.3 Photographs of product samples....................................................................... 14

2.4 Analysis of product samples.............................................................................. 16

2.5 Discussion of results ........................................................................................ 172.6 Conclusions from trial....................................................................................... 18

3.0 Trial 2 - 2.36 to 5mm granulated copper rich plastic.............................................. 19

3.1 Feed Material................................................................................................... 19

3.2 Results ............................................................................................................ 19

3.3 Photographs of product samples ....................................................................... 20

3.4 Analysis of results samples ............................................................................... 22

3.5 Discussion of results ........................................................................................ 23

3.6 Conclusions from trial....................................................................................... 23

4.0 Trial 3 - Copper-rich plastic without pre-treatment ................................................ 23

4.1 Feed Material................................................................................................... 23

4.2 Results ............................................................................................................ 24





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5.0 Trial 4 - +5mm milled copper rich plastic .............................................................. 29

5.1 Feed Material................................................................................................... 29

5.2 Results ............................................................................................................ 29


5.4 Analysis of results samples ............................................................................... 32



6.0 Trial 5 - 3mm to 5mm hammer milled copper rich plastic....................................... 33

6.1 Feed Material................................................................................................... 33

6.2 Results ............................................................................................................ 33

6.3 Photographs of product samples....................................................................... 34




7.0 Trial 6 - 0mm to 3mm milled copper rich plastic.................................................... 37

7.1 Feed Material................................................................................................... 37

7.2 Results ............................................................................................................ 37

7.3 Photographs of product samples ....................................................................... 387.4 Analysis of product samples.............................................................................. 41



8.0 Economic calculation ........................................................................................... 43

9.0 Overall final conclusions of the trial ...................................................................... 46

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List of figures

Figure 1: Photograph of the trial equipment...................................................................... 6Figure 2: Close up of wet shaking table deck .................................................................... 7Figure 3: Schematic indicating where each of the product fractions is collected in relation tothe table......................................................................................................................... 9Figure 4: Photograph of the -2.36mm granulated copper-rich plastic feed material ........... 12Figure 5: Photograph of the -2.36mm material on the wet shaking table .......................... 13Figure 6: Photograph of trial 1 concentrate 1.................................................................. 14Figure 7: Photograph of trial 1 concentrate 2.................................................................. 14Figure 8: Photograph of trial 1 concentrate 3.................................................................. 15Figure 9: Photograph of trial 1 middlings ........................................................................ 15Figure 10: Photograph of trial 1 tailings .......................................................................... 16Figure 11: Photograph of concentrate 1 from scavenge trial ............................................ 18Figure 12: Photograph of the +2.36 mm granulated copper rich plastic material ............... 19Figure 13: Photograph of trial 2 concentrate 1 ................................................................ 20Figure 14: Photograph of trial 2 concentrate 2 ................................................................ 21Figure 15: Photograph of trial 2 concentrate 3 ................................................................ 21Figure 16: Photograph of trial 2 middlings ...................................................................... 22Figure 17: Photograph of trial 2 tailings .......................................................................... 22Figure 18: Photograph of the copper-rich plastic material as it is .................................... 24Figure 19: Wet shaking table in operation on th e copper-rich plastic without size reduction.................................................................................................................................... 25

Figure 20: Photograph of trial 3 concentrate 1 ................................................................ 25Figure 21: Photograph of trial 3 concentrate 2 ................................................................ 26Figure 22: Photograph of trial 3 concentrate 3 ................................................................ 26Figure 23: Photograph of trial 3 middlings ...................................................................... 27Figure 24: Photograph of trial 3 tailings .......................................................................... 27Figure 25: +5mm milled copper-rich plastic feed material................................................ 29Figure 26: Trial 4 concentrate 1 ..................................................................................... 30Figure 27: Trial 4 concentrate 2 ..................................................................................... 30Figure 28: Trial 4 concentrate 3 ..................................................................................... 31Figure 29: Trial 4 middlings ........................................................................................... 31

Figure 30: Trial 4 tailings ............................................................................................... 32Figure 31: 3-5mm milled copper rich plastic feed material ............................................... 33Figure 32: Trial 5 concentrate 1 ..................................................................................... 34Figure 33: Trial 5 concentrate 2 ..................................................................................... 34Figure 34: Trial 5 concentrate 3 ..................................................................................... 35Figure 35: Trial 5 middlings ........................................................................................... 35Figure 36: Trial 5 tailings ............................................................................................... 36Figure 37: 0-3mm hammer milled copper rich plastic material.......................................... 37Figure 38: Wet shaking table in operation on the 0-3mm hammer milled material............. 38Figure 39: Trial 6 concentrate 1 ..................................................................................... 38Figure 40: Trial 6 concentrate 2 ..................................................................................... 39

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Figure 41: Trial 6 concentrate 3 ..................................................................................... 39Figure 42: Trial 6 middlings ........................................................................................... 40Figure 43: Trial 6 tailings ............................................................................................... 40

List of tables

Table 1: Throughput information for trial 1 ..................................................................... 13Table 2: Mass balance results for trial 1.......................................................................... 16Table 3: Analysis of feed, middling and tails fractions from trial 1 .................................... 16Table 4: Analysis of concentrate 1, 2 and 3 from trial 1 ................................................... 17Table 5: Results of copper anaylsis including product sepaartion efficiency, Q................... 17

Table 6: Throughput information for trial 2 ..................................................................... 20Table 7 : Mass balance results for trial 2......................................................................... 23Table 8: Throughput information for trial 3 ..................................................................... 24Table 9: Mass balance results for trial 3.......................................................................... 28Table 10: Throughput information for trial 4 ................................................................... 30Table 11: Mass balance results for trial 4........................................................................ 32Table 13: Throughput information for trial 5 ................................................................... 33Table 14: Mass balance results for trial 5........................................................................ 36Table 15: Throughput information for trial 6 ................................................................... 37Table 16: Mass balance results for trial 6........................................................................ 41

Table 17: Results of analysis on feed, middling and tails from trial 6 ................................ 41Table 18: Analysis of concentrates 1, 2 and 3 ................................................................. 41Table 19: Results of copper analysis for trial 6 including product separation efficiency, Q .. 41Table 20: Payback calculation for a wet shaking table ..................................................... 44

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1.0 Information from trial

Trial host : SGS Mineral Services, the trial was conducted at a facility in Cornwall, UK.

Trial equipment: Holman Wilfley wet shaking table

Trial date : 10 th February 2009

1.1 Photograph of trial equipmentFigure 1 is an annotated photograph of the wet shaking table used in the trial.

Feed hopper Feed trough

Water supply to table

Product collection trough

Tailings product

outlet in

buckets

Deck with riffles

Additional water can be added to the feed here

Head motion

Figure 1: Photograph of the trial equipment

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Copper collects off this edge of the table

Water flows over the table in this direction

Top edge

Bottom edge

Figure 2: Close up of wet shaking table deck

The table moves backwards and forwards in the direction of the arrow in Figure 2 . The

riffles shallow longitudinal ridges - can clearly be seen in the photograph. The rifflesdecrease in height from the bottom edge to the top edge of the table. Water flows over thetable from the top edge to the bottom edge.

1.2 Description of trial equipmentThe wet shaking table at SGS mineral services in Cornwall is a half sized Holman Wilfleytable. This means it has a quarter of the area of a full sized unit but operates in the sameway as a full table.

Figure 1 shows the feed point in the corner of the table where the feed material is added.Water flows out of holes in a pipe which runs along the top of the table. There is also aseparate supply of water into the feed trough.

In operation, the table moves forward and backward, this motion is called the stroke. Thetable is made with shallow longitudinal ridges running from one side to the other called

riffles. The movement of the stroke is in the direction of the riffles. The table is pushedforward with a slow stroke, tensioning a spring as it does so. When the table reaches thespecified stroke length the spring then releases its tension and pulls the table back quickly,hitting the retaining stops. As the table moves forwards the particles rise and aremomentarily suspended. As the table moves backwards the dense particles settle backdown and the motion gradually causes the particles to move along the riffles in the directionof the tables forward stroke. The light material stays in the upper layer and flows down

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over the riffles with the flow of water. An analogy for the movement would be to compare itto a magician pulling a table cloth from under the table contents.

In the context of WEEE separation, copper (coarse, dense material) will settle against theriffles and travel upwards to the far side of the table. Plastic will settle in the upper layerand will travel down over the riffles with the water to the bottom edge of the table.

The height of the riffles decreases along the length of the table from the feed to the productend. The riffles are higher near the feed and tailings edge of the table, approximately 7-8mm high. The riffles decrease in height to only a few millimetres near the concentrationend and top edge of the table. The riffles are approximately 5cm apart. The plasticparticles jump over the high riffles whilst the copper travels up the riffles. The height of theriffle is connected to the material being processed on the table and different riffle patternscan be used depending on the material being processed. For coarser particles, common

within the recycling industry, the height of the riffles can be as much as 20-25mm.

Depending on the type of material, the size of table used in this trial would be expected toprocess 400-450kg/hr. A full size table, dimensions 5.8m long x 1.75m wide x 1.2m highwith a nominal deck area of 8.0m 2, can handle around 2-2.5 tonnes per hour. If thematerial is coarse and has a close size distribution then the throughput can be as high as3.5-4.0 tonnes per hour. Finer material or material with a wide size distribution will have alower throughput.

There are four process variables for a wet shaking table:

Stroke length (maximum stroke length of 19mm);

Deck angle;

Wash water flow rate; and

Position of splitter plate.

The first three variables have an effect on whether a separation is achieved. The last onehas an effect on the products collected both in terms of quantity and quality.

The stroke length is the distance the table moves forwards and backwards. For all the trialsit remained constant at 15mm. The stroke can be increased to a maximum of 19mm forcoarse material or decreased to 5mm for very fine material. If the particle size is large andthe feed material has a low density then a longer stroke is required to separate the particles.

The deck angle can be adjusted from 0 to a maximum of 9. During the trials the deckangle was set at 7. Typically for fine material a flatter deck angle is used but the actualsettings need to be fined tuned during start up and are relative to the density of thematerial.

The feed rate should be kept constant and the solids feed density should be around 25%.This is to ensure that a steady state on the deck is maintained, as fluctuations in the flow of

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material will affect the separation. The wash water flow rate range is 18 to 38 litres perminute.

The table produces five product fractions, illustrated in Figure 3 . There are threeconcentrate fractions produced at the end of the table which consist of the dense material.Concentrate 1 is from the top corner, concentrate 2 is from the upper middle part of thetable and concentrate 3 is from the lower middle part of the table. Beneath these threefractions, at the bottom corner of the table, is a fraction known as the middlings. Thisfraction will often contain a mixture of the concentrate material and the tailings material andmay need reprocessing. At the centre bottom edge of the table is the tailings fraction whichis the light material. The table can also be tuned for a three way split, one product in theconcentrate, one product in the middlings and one product in the tailings. The coppermaterial will be found in concentrates 1, 2 and 3. Glass may be found in concentrate 3whilst the middling and tailings are mainly plastic.

Concentrate 1

Concentrate 2

Concentrate 3

Tailings

Riffles

Direction of table movement

Middlings

Figure 3: Schematic indicating where each of the product fractions is collected in relation tothe table

A moveable splitter plate determines what material is collected as concentrate 3 and whatmaterial is rejected in the middlings. During operation the bed of material on the table isobserved in order to determine if the splitter plate position needs to be adjusted. It shouldbe positioned just at the point where the two materials being separated form a distinct line.

Once correctly set, the table will operate in steady state with constant flows of materials, sothe plate should not require further adjustment. If the splitter plate is positioned incorrectly,valuable product (i.e. copper) could be rejected to the middlings fraction, which would thenneed reworking in order to recover the copper. Conversely, the splitter plate could bepositioned so that the concentrate contains less valuable materials (i.e. plastic/glass), whichis also undesirable. If concentrate 3 contained very little copper and more plastic/glass thenit should be directed into the middlings fraction.

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1.3 Trial objectivesThe overall objective of the trial was to separate valuable metals from glass, stone andplastic. The specific aim was to produce a high purity copper stream which has a saleable

potential. The key to achieving an effective separation is likely to be the particle size andshape.

Market research indicates that the combustible component of the copper fraction must bereduced to below 5% by weight to make it attractive to the majority of copper smelters inEurope. A higher content of stone and glass can be tolerated as they are inert in thesmelter. However separating copper from stone and glass increases the value of bothfractions. The stone and glass has no value when mixed and sold with copper but may besaleable as a useful aggregate substitute if it can be separated with a low copper content.

1.4 Sample materialThe samples used for these trials were copper-rich plastic fraction sourced from AxionsWEEE processing plant in Salford, UK.

The copper-rich plastic was size reduced in two different ways: granulation and hammermilling. This produced five different fractions, along with the original material itself fortesting. The different samples were chosen to allow the effects of particle size on theseparation to be investigated.

The six samples were:

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In order to identify any losses of copper in the middlings and tailings fractions a sodiumpolytungstate solution was used as a sink-float medium. This method was chosen as anyresidual copper would be very small and difficult to hand sort. The same procedure wasapplied to the feed material to allow the analysed feed composition and the back calculatedfeed composition to be compared.

The same method was used for samples of feed, middlings and tailings. A small samplespear was used to take a representative sample from each bag. The sample was thenweighed and added to a container of sodium tungstate solution with a density of 1.7g/cm 3.Ideally the copper would sink and everything else would float. The two fractions wereremoved from the container and dried.

Where the material was large enough the fractions were hand sorted. An estimation of thecopper content was made for those fractions where a hand sort was not possible due to

very small particle size.

Once the physical analysis of the samples was completed, product and reject separationefficiencies, Q and R, were calculated.

For this trial the product separation efficiency, Q, is the probability of correctly recoveringcopper to the desired product stream.

The reject separation efficiency, R, is the probability that everything else is correctly sortedto the secondary product stream.

In this case the secondary product stream is of no use and only the copper is a usefulproduct. The three concentrate fractions from the table are classed as the product streamand the middling and tailing fractions is the secondary product.

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2.0 Trial 1 - less than 2.36mm granulated copper rich plastic

2.1 Feed material

The feed material for trial 1 was the


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2.2 Results

Figure 5: Photograph of the -2.36mm material on the wet shaking table

Figure 5 shows the wet shaking table in operation. The clear boundary between the copperand plastic is shown by the line.

The feeding system blocked during the trial and required manual intervention to ensure thetable received a consistent flow of material. The throughput was determined by measuringthe time taken for a known quantity of feed material to pass though the feed system. Theresults are shown in Table 1 . The throughput was quite low but was limited by the capacityof the feeding system, which may need to be changed for this type of material.

Trial Material

Quantity Times Feed rate

g s kg/h1 876 21.0 150.2

r

Table 1: Throughput information for trial 1

A sample of the tailings from the trial was reprocessed to see if there was any copperpresent. This showed that there was no copper so the first pass of the material hadachieved as good a separation as was possible and reworking of the tailings was notrequired.

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2.3 Photographs of product samples

Figure 6: Photograph of trial 1 concentrate 1


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Figure 9: Photograph of trial 1 middlings

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Figure 10: Photograph of trial 1 tailings

2.4 Analysis of product samplesTable 2 shows the mass balance for trial 1. It should be noted that the feed amount was

not weighed It has been back-calculated from the product fractions so the loss/gain is zero.For all other trials the feed amount was correctly weighed and the loss determined.

Trial Feed Amount

Total Output

Loss/Gain

g g % g % g % g % g % g g1 4214.7 193.7 5% 322.9 8% 387.3 9% 867.8 21% 2443 58% 4215 0.0

Con 1 Con 2 Con 3 Middlings Tailings

Table 2: Mass balance results for trial 1

The results of the sink float analysis are shown in Table 3 .

Trial SampleWeight of dry sample

Dry copper weight

% of copper

Feed 15.39 2.6 17%Middlings 10.56 0.24 2%Tails 5.92 0 0%

1

Table 3: Analysis of feed, middling and tails fractions from trial 1

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The hand sorting results are shown in Table 4 .

Fractionweight

Trial 1 g % g % g %Concentrate 1 186 96% 5 3% 2 1% 194Concentrate 2 291 90% 32 10% 0 0% 323Concentrate 3 198 51% 189 49% 0 0% 387

Copper Glass Plastic

Table 4: Analysis of concentrate 1, 2 and 3 from trial 1

Fraction Fraction

weightCopperweight

% Copper purity

% Copper recovered

Feed 4215 717 17%Concentration 1 193.7 186 96% 26%Concentration 2 322.9 291 90% 41%Concentration 3 387.3 198 51% 28%Middlings 867.8 17.4 2% 2%Tails 2443 0 0% 0%

Product totals 4215 692 16% 97%

Q 94%

Table 5: Results of copper anaylsis including product sepaartion efficiency, Q

2.5 Discussion of resultsTable 3 and 4 show the results of the analysis for each of the product fractions from the trial1.

Fraction Fraction

weightCopperweight

% Copper purity

% Copper recovered

Feed 4215 717 17%Concentration 1 193.7 186 96% 26%

Concentration 2 322.9 291 90% 41%Concentration 3 387.3 198 51% 28%Middlings 867.8 17.4 2% 2%Tails 2443 0 0% 0%

Product totals 4215 692 16% 97%

Q 94%

Table 5 shows just the copper analysis as this is the main area of focus. It can be seen thatthe copper concentration in concentrate 1 is 96% and in concentrate 2 is 90%. Both ofthese are high purities for copper fractions recovered from WEEE and should meet thecopper smelters requirements. 67% of the copper in the feed was recovered in

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3 but

The back cal nalysed

isnd 3.

The results concluding

concentrates 1 and 2. Over a quarter of the copper was recovered to concentrateonly at a 50% purity level.

culated copper content of the feed, 16%, is very close to the actual a

The product separation efficiency, Q value (which is the probability that the copper

of a scavenge on the trial 1 tailings is illustrated in Figure 11 below,

copper content of the feed, 17%, which shows that the analysis is consistent.

correctly sorted into one of the three product fractions) is 94% for concentrates 1, 2 aThis is a high separation efficiency and means that the majority of the copper is recovered.

that no copper had been lost in the tailings fraction in the first trial.

Figure 11: Photograph of concentrate 1 from scavenge r l

2.6 Conclusions from trialThe tion of copper from plastic with this feed material.

t ia

technique is very good for the separa

A copper fraction with 26% recovery at 96% purity was produced. Taking into account allthree concentrate fractions the copper recovery is 95%, at a purity of 75%. The probabilitythat the copper is correctly sorted into one of the concentrate fractions is 94%. Thereforethe trial objective of recovering the copper into a saleable fraction has been achieved. Withfurther system adjustments and fine tuning even better results may be obtained.

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3.0

The er-richplas te

Trial 2 - 2.36 to 5mm granulated copper rich plastic

the 2.36 to 5mm fraction of the granulated copp3.1 Feed materialfeed material for trial 2 wastic ma rial.

Figure 12: Photograph of the +2.36 mm granulated copper rich plastic m terial

3.2 ResultsTh copper in the feed material for trial 2, compared to trial 1, whichind f the ction when the material

zone between the copperand plastic. It may be po ce only glass in the

ults are shown in Table 6.

a

ere was much lessicates that most o copper went into the less than 2.36mm fra

ss which occurred at the transitionssible to fine tune the machine to produ

was granulated and sieved.

There was a clear layer of gla

middling fraction.

The throughput res

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Trial Material

Times Feed rateQuantity

g s kg/hr2 540 20.5 94.8




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3.4 Analysis of results samples Table 7 shows the mass balance for trial 2.

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Trial Feed Amount

Total Output

Loss/Gain

g g % g % g % g % g % g g2 10559 44 0.4% 272 3% 51 0.5% 1440 14% 8257 78% 10064 495


Table 7 : Mass balance results for trial 2

The losses in the mass balance are due to the collection technique used for the material.Buckets were used to collect the product fractions. Losses occurred when these wereswapped over and also when the buckets were emptied.

Because it was clear during the trial that there was very little copper present in the samplethe decision was made not to analyse each product fraction quantitatively.

3.5 Discussion of results Visual inspection of the samples showed there was very little copper in the concentrate 1fraction; however there were other metals present. There was more copper in concentrate2 whilst concentrate 3 contained glass, plate-like plastic particles and copper. Most of thecopper in concentrate 3 was in the form of polyvinylchloride (PVC) coated wires: if thematerial was granulated to a smaller size it would liberate the copper from the PVC and thelevel of copper recovery would improve.

3.6 Conclusions from trialThe technique did not work very well with this feed material, but this is not thought to be

due to the particle size, but more due to the fact that the copper content of the materialwas very low. This is a characteristic of the feed material, with the copper tending toappear in the smallest particle size fraction during the granulation process.

4.0 Trial 3 - Copper-rich plastic without pre-treatment

4.1 Feed materialThe feed material for trial 3 was the copper-rich plastic with no size reduction.

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Figure 18: Photograph of the copper-rich plastic material as it is

4.2 ResultsDuring the trial it was observed that the material tended to flow over the table and theriffles did not catch the copper. Figure 19 shows the material on the table and it can beseen that it has lumped together on the table and not spread out correctly. This is probably

due to the shape of the plastic particles; the plate-like shape means they flow with thewater over the riffles.

The separate throughput timings are shown in Table 8.

Trial Material


g s kg/hr3 Test 1 666 20.0 1203 Test 2 780 20.5 137

Average 128


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Figure 19: Wet shaking table in operation on the copper-rich plastic without size reduction



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4.4

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Analysis of product samples Table 9 shows the mass balance details for trial 3.

Trial Feed Amount

Total Output

Loss/Gain

g g % g % g % g % g % g g3 10676 53.6 1% 390.8 4% 952.7 9% 4670.0 44% 3666.6 34% 9733.7 942.3



Again there was clearly very little copper in this material, in comparison to trial 1, soquantitative analysis was not conducted on each of the product fractions.

4.5 Discussion of resultsThe separation of this material was not very good as the particles were too big. The plasticparticles tend to be in the range 8-12mm but the copper can vary from very small pieces,only 2-3mm long and 0.5mm in diameter, up to larger pieces of 10-15mm in length. Higherriffles and an increased flow of water may possibly improve the separation but this wouldrequire further work to be undertaken in order to confirm this.

There was very little copper material in concentrate 1, only 1% of the feed, and was 4% ofthe feed in concentrate 2. Both fractions consisted of a mixture of copper and plastic.

Concentrate 3 contained 9% of the feed but again this was both copper and plastic. Thelargest amount of material was in the middlings fraction.

During the trial the plastic often formed a mass on the table which did not allow the copperto separate out correctly. At the boundary between the copper and plastic, as seen inFigure 19, the plastic particles did not spread out evenly and formed lumps of materialwhich prevented the separation from occurring.

4.6 Conclusions from trialProcessing the material as it is does not yield satisfactory results and the trial objective was

not achieved. This means that in order to recover the copper using a wet shaking table, thefeed material must be size reduced before processing.

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5.0 Trial 4 - +5mm milled copper rich plastic

5.1 Feed material

The feed material for trial 4 was the +5mm fraction of the hammer milled copper-richplastic.

Figure 25: +5mm milled copper-rich plastic feed material

5.2 Results At the start of this trial it appeared that there was no separation occurring but it becameapparent that there was very little copper in the sample.

The table tilt was increased to 9 to see if this helped achieve a separation, but it had noeffect.

The water pressure dropped during this trial, which had an effect on the wetting of thematerial, which was very dry. Even taking this into account the separation would still havebeen poor due to the small amount of copper in the feed.

Table 10 shows the throughput information for trial 4, which is in the same range as theother trials.

Trial Material


g s kg/h4 585 20.4 103.2

r

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Figure 26: Trial 4 concentrate 1


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Figure 29: Trial 4 middlings

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Figure 30: Trial 4 tailings

5.4 Analysis of results samples

Trial Feed Amount

Total Output

Loss/Gain

g g % g % g % g % g % g g


4 10214 260 3% 2343 23% 2746 27% 3074 30% 1439 14% 9863 351

Table 11 shows the mass balance for trial 4.

Trial Feed Amount

Total Output

Loss/Gain

g g % g % g % g % g % g g4 10214 260 3% 2343 23% 2746 27% 3074 30% 1439 14% 9863 351



As no separation was observed, further analysis was not conducted on any of the productfractions.

5.5 Discussion of resultsThere was very little copper in this sample. The copper was concentrated in the smaller sizefractions produced by hammer milling. The material also appeared to be too dry. Wettingthe feed prior to feeding onto the table may have improved the separation slightly.

5.6 Conclusions from trialThere was very little copper present in this fraction so no significant separation occurred.

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6.0 Trial 5 - 3mm to 5mm hammer milled copper rich plastic

6.1 Feed materialThe feed material for trial 5 was the 3 to 5mm fraction of hammer milled copper-rich plastic.

Figure 31: 3-5mm milled copper rich plastic feed material

6.2 Results Again there was very little copper in this sample of material so no significant separationoccurred. There was a small amount of copper and plastic present in the middling andtailings fractions and some balled up copper was observed in concentrate 1 and 2.

Table 12 shows the throughput information for trial 5.

Trial Material


g s kg/h5 542 20.0 97.6

r


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6.4 Analysis of product samplesTable 13 shows the mass balance for trial 5.

Trial Feed

Amount

Total

Output Loss/Gain

g g % g % g % g % g % g g5 8549 34.4 0.4% 271 3% 292 3% 1346 16% 6280 73% 8224 326



As the observed levels of copper in the feed material were low, no further analysis wasconducted on any of the product fractions.

6.5 Discussion of resultsIt appears that during the size reduction process the copper has concentrated into thesmallest particle size fraction and hence there was very little copper present in this fraction.

6.6 Conclusions from trialThe results from trial 5 are inconclusive because of the small amount of copper in the feed.

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7.0 Trial 6 - 0mm to 3mm milled copper rich plastic

7.1 Feed materialThe feed material for trial 6 was the 0-3mm fraction of the hammer milled copper-richplastic.

Figure 37: 0-3mm hammer milled copper rich plastic material

7.2 ResultsIt was noted during the trial that the feed material contained a significant proportion ofplastic particles greater than 3mm. This means that the material was not screenedcorrectly, perhaps due to a hole in the screen.

The throughput measurement for this trial is shown in Table 14.

Trial Material


g s kg/h6 664 30.0 79.7

r


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Figure 38: Wet shaking table in operation on the 0-3mm hammer milled material

Figure 38 shows a photograph of the wet shaking table in operation during the trial. At thetop edge of the table a clear copper stream can be seen flowing up and along the riffles. Inthe lower section of the photograph there is a darker material, mainly plastic and dust whichis flowing down over the riffles.



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7.4

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Analysis of product samples Table 15 shows the mass balance for trial 6. Table 16 and 18 are the results of the analysison each of the product fractions. Table 18 shows the results for the copper component

only.

Trial Feed Amount

Total Output

Loss/Gain

g g % g % g % g % g % g g6 9976 25.7 0.3% 389.3 4% 324.7 3% 361.3 4% 8400 84% 9501.0 475.0



Trial SampleWeightof dry

sample

Dry copper

weight

% of copper

Feed 45 6 12%Middlings 24 7 31%

Tails 12 0.1 1%6

Table 16: Results of analysis on feed, middling and tails from trial 6

Sample weight

Trial 6 g % g % g % gConcentrate 1 11 41% 0 0% 15 58% 26Concentrate 2 346 89% 0 0% 42 11% 389Concentrate 3 313 96% 5 2% 7 2% 325

Copper Glass Plastic

Table 17: Analysis of concentrates 1, 2 and 3

Fraction Fraction

weightCopperweight

% Copper purity

% Copper recovered

Feed material 9976 1197 12%Concentration 1 26 11 41% 1%

Concentration 2 389 346 89% 29%Concentration 3 325 312 96% 26%Middlings 361 112 31% 9%Tails 8400 84 1% 7%

Total feed material back calculated from product weights and compositions

9501 865 9%

Mass balance error 475 332 3%

Product separation efficiency Q 56%

Table 18 : Results of copper analysis for trial 6 including product separation efficiency, Q

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7.5 Discussion of resultsThe concentrate fractions contained a significant number of large pieces of plastic (>3mm),which should not have been present in a 0-3mm sieved fraction. This was probably due to a

fault with the screen used to prepare the trial samples. This did have some effect on theseparation. If the material had been sieved correctly then a better separation wouldprobably have been achieved because the oversize plastic particles tended to follow thecopper into the concentrate fraction.

The content of copper measured in the feed material was 12%. However back calculatingthe feed composition from the measured product compositions gave an estimate of 9%copper in the feed. This discrepancy is significant and may be due to loss of materialsthrough spillages during the trial.

The product separation efficiency, Q, was rather low at 56%. This is the probability thatcopper was correctly sorted into the concentrate fractions.

10% of the copper was lost to the middling and tailings fractions. This reduces the Q value.Therefore the machine settings should possibly be adjusted, recover more copper into theconcentrate fraction, for example by repositioning of the splitter plate between concentrate3 and the middlings fractions.

A small amount of copper was collected in the tailings fraction. It was likely that this wasdue to poor wetting of the material which caused some of the copper to be swept over theriffles with the plastic.

The product photographs show that concentrate 1 contained a small amount of copper andsome large plastic chips, concentrate 2 contained more copper along with some large plasticchips and concentrate 3 contained both copper and plastic.

If the feed material had been screened correctly and the larger pieces of plastic removedthen the results would have been better as less oversize plastic would have been carriedinto the concentrate fractions.

7.6 Conclusions from trialThis trial showed that copper in the 0-3mm fraction from the hammer milled product couldbe recovered by the wet shaking table. The separation efficiency was rather low at 56% butthe overall copper content of the three concentrate fractions was high at 90%. Theconcentrate fractions contained a total of 8.7% combustible plastic. If oversize plasticmaterial had not leaked through the screen then the concentrates would have contained lessthan 5% plastic. This would make the material acceptable for processing by conventionalcopper smelters.

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8.0 Economic calculation A simple payback calculation was completed in order to determine the economic potential of

the wet shaking table for recovery of copper from WEEE plastic mixtures.

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Trial Host Trial Holman WilfleyEquipment Equipment Wet Shaking Table

Capacity te/hr 1Cost of unit including feed system and installation

180000

Basis of operation hr/yr 3000Overall Equipment Effectiveness OEE % 70%Plant Input te/yr 2100

Operating CostsWaterQuantity kg/hr 100Cost (assuming 2/te) /hr 0.20

PowerQuantity kW 50Cost (assuming 10p/kW hr) /hr 5

Water and Power costs /te of feed 5.20Water and Power costs /yr 10920

Wear costs for granulator /te feed 6/yr 12600

Labour costs (assuming 15/hr) 45000

Annual process licence costs 0

Total Operating Costs 68520Revenue

Assume 10% of feed is separated as product

Product extracted te/yr 210

Value of product /te 1000

/yr 210000Margin /yr 141480

Payback time months 15

Table 19: Payback calculation for a wet shaking table

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The calculation assumes a capacity of 1 tonne per hour for a full size Holman Wilfleyseparation table and an installed cost for the unit, including feed granulator, of 180,000.

The plant is assumed to operate 12 hours per day, 5 days a week, 50 weeks a year, giving3,000 hours of operation per year.

The payback calculation assumes a overall equipment effectiveness (OEE) of 70%, wherethe OEE is defined as follows:

hoursrunavailable

hoursrunactual

tyavailabili

productionspecificatonof %ratequality

tthroughpurated tthroughpuactual

ratecapacity

tyavailabilixratequalityxratecapacityOEE

Therefore the overall plant throughput will be 2,100 tonnes per year,

Operational costs:

The feed material is currently sent to landfill and once the copper has been recovered theresidue material will still be sent to landfill so there is no net cost or benefit from disposal ofthe residue fraction.

It is assumed that 10% fresh water is lost per tonne of material sent to landfill with a water

cost of 2/te.

A total power consumption of 50 kW is assumed for operation of the granulator, separationtable and associated pumps and sieves. The power cost is assumed to be 10p/kW hr.

Wear costs for the granulator are estimated to be 6 per tonne of feed.

The calculation assumes that the system will require one operator at a total job cost of45,000 per year.

The revenue estimate assumes that 10% copper is extracted the feed. This means that the

plant will recover about 210 tonnes of copper concentrate. The value of this material willfluctuate but is assumed to be approximately 1,000 per tonne.

Therefore the margin is 141,480 and so the payback time is nine months.

The economic assessment shows that a unit processing 1 tonne per hour of size reducedcopper-rich plastic from WEEE processing should generate an operating margin of about140,000/year. This should pay back the 180,000 installed cost for the system in around15 months.

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9.0 Overall final conclusions of the trialFine copper can be successfully recovered from the following feed materials using a wetshaking table:

-2.4mm granulated copper-rich plastic from secondary WEEE processing; and 0-3mm hammer milled copper-rich plastic.

For the -2.36mm granulated material 95% of the copper was recovered, at a concentrationof 75% copper. For the 0-3mm hammer milled material 56% of the copper was recoveredat 90% purity.

The wet shaking table was partially successful when trying to recover copper from the+2.4mm size fraction of the granulated copper rich plastic material.

The wet shaking table, could not recover copper efficiently from copper-rich plastic mixtureswhich had not been size reduced.

The copper content of the 3-5mm and +5mm fractions from hammer-milled copper-richplastic was very low so there was no benefit in trying to separate these fractions.

The trial showed that when copper-rich plastic is size reduced, the majority copper tends toend up in the smallest fraction; copper-rich plastic should therefore be milled or granulatedto less than 5mm, ideally less than 3mm, prior to using a wet shaking table for copperrecovery.

The feed material should be fully wetted before processing in order to assist withseparation.

The wet shaking table can potentially be tuned to produce a glass fraction in the middlings.However the presence of glass in the copper fraction is not a problem for copper smeltersbecause it ends up in the furnace slag fraction and does not interfere with furnaceoperation.

The throughput of the quarter size table used for the trial varied from 80 kg/hr to 150 kg/hrdepending on the material being processed. This means that the throughput of a full sizetable should be in the range 320 to 600 kg/hr. Axion believes that a modified feedmechanism should allow a single full size table to achieve 1te/hr with a -3mm feed material.

holman wilfley trial report final

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