PAPER_Interpretación Curvas Escalamiento

7/30/2019 PAPER_Interpretacin Curvas Escalamiento

1/14

Interpretation of the recovery/time curve and scale-up from column

leach tests on a mixed oxide/sulfide copper ore

Ronald J. RomanLeach, Inc.

4741 N. Placita del Sol

Tucson, AZ 85749

Jose Hector Figueroa P. and Jorge Enrique Ruiz H.

Mexicana de Cananea S.A. de C.V.

Av. Juarez S/N

Cananea, Sonora 84620

Mexico

Jorge Helleon G.Mexicana de Cobre, S.A. de C.V.

Aptdo 20

Nacozari, Sonora 84340

Mexico

Efrn Prez S.

University of Sonora

Dept. of Geology

Hermosillo, Sonora 83000

Mexico

ABSTRACT

The shrinking core model for coarse particle leaching has been generally accepted as

describing the leaching of a copper oxide or sulfide ore. However, when a mixed

oxide/sulfide ore is leached this model can not be used in its simple form because at least two

and possibly three separate leaching processes are occurring simultaneously (dissolution of

oxide copper minerals, secondary copper minerals and primarily copper minerals). It has been

impossible to isolate their individual leaching curves from the recovery/time curve generatedby the column leach test. This paper describes a tests program carried out at the Groupo

Mexico, Mexicana de Cobres La Caridad operation in which the individual recovery/time

curves for the leaching of copper oxide mineral, secondary copper mineral and primary

copper minerals were developed from standard column leach tests. Once the individual

recovery/time curves were developed scale-up of the column leach test results to the

commercial heap leaching operation is possible by using the shrinking core model.


2/14

1

INTRODUCTION

A fifteen-year mine plan is being prepared by the staff at La Caridad. This mine plan

will recognize and incorporate the leaching response of the individual ore blocks so the

mining sequence can be based on the overall economics of the operation including the

recovery of copper from the leach ore as well as the recovery of copper from the milled ore.

This paper briefly describes part of the column leach test program that was undertaken at La

Caridad and by the metallurgical staff at La Caridad with the assistance of Leach, Inc. The

objective of this column leach program was to develop a correlation between the leachability

of the ores from the La Caridad pit and the geologic and/or chemical characteristics of the

individual ore blocks. The leachability of an ore is defined by the recovery/time curve

generated by leaching the ore under plant conditions.

The mine plan is made up of thousands of blocks that are contained within the pit

limits. In order to determine if an individual block is to be considered waste, flotationfeed or heap leach feed the amount of copper which might be recovered from that block

needs to be estimated. Normally, to obtain that estimate for the option of heap leaching a

column leach test is required. With the column data in hand, the recovery/time curve for the

commercial heap leaching operation is projected based on the shrinking core model (1,2).

However, conducting thousands of column leach tests, one for each ore block, would be

prohibitive from both the cost and the time required. An additional problem is that shrinking

core models are based on the rate of movement of the interface between the leached shell and

the unleached core of the ore particle. When the ore contains copper in more than one form

(oxide, secondary sulfides and/or primary sulfides) then there exists more than one interface.

It is therefore necessary to experimentally measure the rate of copper recovery for each of

the forms of copper. No experimental technique is available to divide the experimentalrecovery/time curve from a column leach test into the individual recovery/time curves for the

different copper components of an ore. The division of the overall recovery/time curve into

its individual components is necessary if the shrinking core model is to be used to project the

column leach test results to the commercial heap leach operation.

It was a primary objective of this project to develop a technique to divide the

experimentally determined recovery/time curve into individual recovery/time curves for each

form of copper present in the ore and secondly to find an easily measured characteristic of

an ore sample which correlates with the recovery/time curve under the commercial heap leach

conditions. Because the copper produced from leaching the ore is recovered over several

years, not only must the final recovery be estimated but the complete recovery/time curveneeds to be predicted so that the cash flow from the annual copper production from that ore

block can be properly discounted when assigning a value to the ore block.


3/14

2

PROCEDURE

The column leach test program was divided into four parts:

1. Determination of the reproducibility of the column leach test through duplicate tests,

which were run at the La Caridad lab; and duplicate tests, one run at La Caridad and

the other one run in the lab at Mountain States R & D International, Inc. (MSRDI)

in Vail, Arizona.

2. Determination of the change in the leachability of an ore resulting in changes in the

operating parameters of the column leach test i.e. leach solution irrigation rate,

column height, column diameter, leach solution chemistry, leach/rest cycle schedule,

etc. This phase of the column test program was used to establish the procedure for

the standard column leach test and to demonstrate that the leaching of the ore

followed the shrinking core model of leaching.

3. Determination of the leachability of ore samples from throughout the La Caridad

deposit and analysis of the leachability in an attempt to correlate the leachability of an

ore sample with geological and/or chemical parameters of the ore sample.

4. Projection of the column leach test date to leachabilities for that ore sample when

leached on the commercial heaps.

This paper reports on the third part of this project: developing a correlation between

the leaching recovery/time curve and the geologic and/or chemical characteristics of an ore

sample.

The La Caridad deposit has been divided into four zones based on both the geological

and mineralogical characteristics of the rock. Ore samples for column leaching were collected

from each of the four zones.

In addition to this classification of the ore blocks, each ore block can be classified

based on copper grade. Two classes based on copper grade were selected: Cu(total) equal

to or greater than 0.15 percent and equal to or less than 0.30 percent, and Cu(total) greater

than 0.30 percent.

The most prevalent copper minerals in the La Caridad deposit are chalcocite, covelliteand chalcopyrite. In addition some oxide copper minerals as well as bornite are present.

Because the responses of these minerals to leaching differ greatly, a third classification was

established: the percentage of leachable copper. The leachable copper is defined as that

copper contained in minerals solubilized by a five percent sulfuric acid solution or a ten


4/14

3

percent sodium cyanide solution (3). The fraction of the contained copper which is either acid

soluble or cyanide soluble is called the Solubility Index or S.I. The other copper minerals,

which by this definition are not leachable, are chalcopyrite and refractory mixed iron or

manganese copper oxide minerals. Each ore block was then classified by its leachable

copper content: less than 25 percent, equal to or greater than 25 percent but less than 50

percent, equal to or greater than 50 percent but less than 75 percent and equal to or greater

than 75 percent.

In those column tests in which different ore samples were being evaluated for their

leachability a standardized test procedure was used. The test procedure was designed to

allow both the rate of copper solubilization and the ultimate copper recovery to be determined

in as simple a test as possible. The standard test procedure was selected after running a

preliminary group of 13 column leach tests in which the operating parameters were varied.

Parameters varied included column height, column diameter, irrigation rate, cure procedure,

rest cycle schedule and leach solution chemistry. In summary, the standardized test leaches

a 90 kg ore sample crushed to -38 mm. for 90 days in a 152 mm diameter column 3.0 metersin height. A sample for a size/assay test is split from the ore sample and each size fraction is

analyzed for acid soluble copper, cyanide soluble copper and total copper. The leach solution

used in the column test is raffinate from the La Caridad heap leach circuit containing

approximately 3.0 gpl total iron of which approximately 2.8 gpl is ferric iron. The free acid

content of the leach solution is approximately 6 gpl. The column is irrigated at a rate of

0.0034 lps/m and no rest or cure cycles are used.2

Pregnant leach solution (PLS) samples are collected daily, their volumes determined

and the solution assayed for ferrous iron, total iron, free acid and total copper. The ferric iron

is calculated from the total iron and ferrous iron assay.

REVIEW OF COLUMN DATA AND SIMULATION OF RESULTS

The factors, which determine the recovery/time curve, can be divided into two groups:

the operating parameters of the heap leach or column leach and the ore characteristics.

Operating parameters include all those parameters that the plant operator can independently

select or that are a result of one of the parameters under control of the operator. Particle

size, lift height and irrigation rate fall into this group. In addition heap porosity (the

percentage voids within the heap) is also in this group since it is determined by the particle

size, heap height and the manner in which the heap was built. The second group (orecharacteristics) consists of parameters that the operator has no control over: ore specific

gravity, porosity, mineralogy and copper mineralogy for example. The primary objective of

this study was to determine a correlation between the ore characteristics (the second group

of parameters) and the recovery/time curve. The relationship between the operating


5/14

4

parameters (the first group of parameters) and the recovery/time curve is based on the

shrinking core model as described by LEACH (4), a software package for simulating a heap

leach operation. All column tests were, therefore, run under conditions as close to identical

as possible so that differences in their recovery/time curves would only result from differences

in the ore characteristics of the individual ore samples use in each column.

Analysis of the column leach test results revealed that the recovery/time curves of all

of the ore samples could be described by three ratios: acid soluble copper to the total copper

in the sample, cyanide soluble copper to the total copper in the sample and insoluble copper

to the total copper in the sample.

Table I summarizes the copper chemistry for all of the column tests run with the

standard column test procedure. The recovery/time curves for a selected few of these tests

are shown in Figure1 in which the recovery of total copper is plotted. In Figure 2 the same

column tests are plotted showing the recovery of soluble copper. The copper recoveries in

the tests were fitted by least squares regression analysis to an equation of the form:

% Rec Cu(total) = A x S.I.(A.S.) + B x S.I.(CN sol.) +C x (Insol Cu) (1)t t t twhere:

% Rec Cu(total) = Recovery of total copper at time t,tA , B and C = Constants, time variable,t t tS.I.(A.S.) = Ratio of acid soluble copper assay to total copper assay,

S.I.(CN sol.) = Ratio of cyanide soluble copper assay to total copper assay,

Insol Cu = Ratio of insoluble copper content to total copper assay.

Equation 1 states that the copper recovery will be a function of the fraction acid

soluble copper content, the fraction cyanide soluble copper content and the fraction insolublecopper content: the basic copper mineralogy of the ore. The equation also presumes that each

of the three forms of copper present will leach independent of the amount of the other two

forms of copper present and that all of the other characteristics of the ore will have no

measurable effect on the recovery/time curve. Although this may be intuitively incorrect, if

the variation in these other characteristics among the test samples is small then their effect on

the recovery/time curve can be small or masked by the effect of the copper mineralogy. In

addition any effect caused by these other characteristics will be indicated by the correlation

coefficient of the regression equation.

The results of the regression analysis are summarized in Table II. The constants, A,

B and C can be interpreted as the recovery of the their respective copper component at thecorresponding times. Figure 3 shows the plots of the constants versus time.

The adjusted correlation coefficient represents the amount of the change in

recovery that is due to ore characteristics incorporated in equation 1. For example, at 20


6/14

5

Table I - Column leach test feed characteristics

Column Zone % % % S.I. Acid S.I. Cyanide S.I. Cyanide S.I. TotalOre Cu(tot), Cu(A.S.), Cu(CN sol), S.I. Acid/

1 1 0.203 0.010 0.016 0.045 0.071 0.625 0.116

2 1 0.211 0.015 0.016 0.064 0.068 0.938 0.131

3 1 0.208 0.033 0.044 0.163 0.218 0.750 0.391

4 1 0.240 0.033 0.097 0.138 0.406 0.340 0.544

6 1 0.304 0.040 0.138 0.148 0.511 0.290 0.659

7 1 0.268 0.028 0.037 0.111 0.147 0.757 0.258

9 1 0.427 0.033 0.160 0.074 0.360 0.206 0.435

11 1 0.419 0.062 0.282 0.145 0.660 0.220 0.806

12 2 0.250 0.012 0.024 0.049 0.098 0.500 0.148

12 2 0.212 0.015 0.031 0.063 0.130 0.484 0.193

14 2 0.267 0.029 0.097 0.115 0.385 0.299 0.500

15 2 0.337 0.035 0.054 0.114 0.175 0.648 0.289

16 2 0.208 0.038 0.134 0.182 0.641 0.284 0.823

17 2 0.291 0.076 0.159 0.251 0.525 0.478 0.776

18 2 0.273 0.019 0.080 0.070 0.296 0.238 0.367

19 2 0.353 0.020 0.015 0.053 0.040 1.333 0.093

20 2 0.377 0.062 0.159 0.164 0.420 0.390 0.583

21 2 0.384 0.083 0.204 0.230 0.565 0.407 0.795

22 2 0.471 0.082 0.280 0.185 0.631 0.293 0.815

23 3 0.198 0.016 0.012 0.083 0.062 1.333 0.145

24 3 0.199 0.013 0.007 0.069 0.037 1.857 0.106

25 3 0.199 0.025 0.021 0.126 0.106 1.190 0.231

26 3 0.392 0.026 0.037 0.065 0.093 0.703 0.159

27 3 0.693 0.222 0.327 0.301 0.444 0.679 0.745

29 4 0.232 0.012 0.023 0.047 0.089 0.522 0.136

30 4 0.218 0.018 0.015 0.085 0.071 1.200 0.156

31 4 0.356 0.020 0.023 0.057 0.066 0.870 0.123

32 4 0.286 0.026 0.027 0.086 0.090 0.963 0.176

33 4 0.414 0.037 0.071 0.094 0.181 0.521 0.27534 4 0.587 0.076 0.296 0.144 0.546 0.264 0.690

35 4 0.484 0.081 0.278 0.175 0.600 0.291 0.775

36 4 0.475 0.106 0.210 0.234 0.464 0.505 0.698


7/14

0

10

20

30

40

50

60

0 20 40 60 80 100

Leach time, days

RecoveryCu(tot),

%

0

10

20

30

40

50

60

70

80

90

0 20 40 60 80 100Leach time, days

RecoveryCu(Soluble),%

6

Figure 1 - Recovery of Total Copper for Selected Column Leach Tests

Figure 2 - Recovery of Soluble Copper for Selected Column Leach Tests


8/14

0

10

20

30

4050

60

70

80

90

100

0 20 40 60 80 100

Time, days

RegressionCoefficient

(CuReco

very,

%)

Cu(A.S.) Cu(CN sol)

7

Table II - Results of Regression Analysis

Time, days A B C Correlation

Adjusted

Coefficient5 63.85 5.75 -2.37 0.818

10 69.73 15.94 -2.65 0.859

15 79.05 21.92 -2.90 0.869

20 81.72 26.72 -2.62 0.871

40 86.04 37.49 -1.41 0.885

60 87.02 43.66 -0.36 0.886

80 88.45 46.54 0.59 0.885

Figure 3 - Regression Coefficients as a Function of Leach Time


9/14

8

days into leaching, equation 1 accounts for 87.1 percent of the change in recovery, the other

12.9 percent must be attributed to factors not included in the equation. These would include

experimental error, variations in operating parameters which were intended to be held

constant in all tests (such as leach solution chemistry, irrigation rate, percent voids in the

column, column height, particle size distribution, etc.) and differences in the leachability of

the ore samples as a result of differences in the ore characteristics which effect the

recovery/time curve, such as the ore porosity and reagent consumption.

Table III contains measured recoveries and the calculated recoveries at selected times

for column tests on 32 ore samples. The measured recoveries versus the calculated recoveries

are plotted in Figure 4.

The numerical values for the C term are interesting from both an academic point as

well as a practical point. The negative value suggests that the chalcopyrite is initially acting

as a preg robber. With increasing leach time this effect is reduced and the chalcopyrite then

contributes to the copper produced by the column. This can be explained by the followingchemical reaction:

CuFeS + Cu 2CuS + Fe (2)2+2 +2

Initially the chalcopyrite reacts with copper in the leach solution, precipitating the

copper as covellite and releasing iron into solution. As leaching progresses the covellite

undergoes dissolution:

CuS + 8Fe + 4H O Cu + SO +8Fe + 8H (3)+3 +2 = +2 +

2 4

and this second reaction releases more copper into solution than the first removes from

solution. This reaction sequence is the typical A B C reaction where chalcopyrite is A,

covellite is B and C represents solubilized copper. Consequently, the constant C is initially

negative but eventually becomes positive.

This explanation of the role of chalcopyrite was supported by the observation that in

some of the leach residues more covellite was found than could be accounted for by the

covellite in the sample head plus the covellite produced from leaching half of the copper from

the chalcocite. In addition, this reaction sequence is known to produce covellite during the

alteration of primary copper deposits. There have been several reports of an induction

period in leaching chalcopyrite ores similar to that suggested by the above sequence ofreactions. They have been attributed to an acclimatization period needed by the bacteria

before taking part in the leaching process.

The chalcopyrite eventually contributes to the production of copper from the heap.

The column tests were not of sufficient duration to establish a recovery/time curve for the


10/14

9

Table III - Column leach test measured and calculated recovery

Column

Recovery, % (measured/calculated)

5 days 10 days 20 days 40 days 60 days 80 days

1 1.91/1.17 3.01/1.91 4.44/3.24 6.67/5.27 8.61/6.69 9.19/7.79

2 1.50/2.39 2.21/3.21 4.05/4.73 6.76/6.79 8.68/8.18 9.24/9.26

3 8.30/10.22 11.37/13.22 17.73/17.55 19.78/21.35 22.45/23.50 23.03/24.95

4 9.55/10.07 14.93/14.89 20.58/20.93 25.24/26.45 28.60/29.57 29.89/31.37

6 12.64/11.59 19.25/11.57 28.68/24.87 35.45/31.43 39.42/35.08 41.29/37.09

7 6.17/6.18 7.45/8.12 9.80/11.06 12.87/14.02 14.15/15.81 15.39/17.10

9 8.63/5.48 11.82/9.43 15.75/14.22 20.82/19.11 23.26/22.00 24.71/23.68

11 17.73/12.61 28.23/20.14 41.76/29.00 50.25/36.98 55.80/41.40 58.42/43.69

12 4.31/1.69 5.93/2.74 7.63/4.41 10.68/6.72 11.73/8.27 12.80/9.4312 6.89/2.86 8.58/4.33 10.40/6.52 13.83/9.17 15.15/10.88 17.04/12.11

14 8.53/8.38 11.97/12.84 16.32/18.38 22.33/23 25.25/26.64 26.43/28.39

15 5.93/6.58 7.48/8.83 10.50/12.11 13.23/15.35 14.33/17.29 15.14/18.63

16 15.86/14.88 23.43/22.43 30.76/31.53 39.65/39.43 44.60/43.75 48.28/46.02

17 22.00/18.50 29.15/25.26 37.26/33.93 45.44/40.94 48.46/44.66 50.50/46.74

18 4.36/4.70 6.72/7.95 10.87/12.01 14.58/16.27 17.35/18.83 19.00/20.39

19 0.74/1.46 1.38/1.92 2.90/3.01 4.66/4.76 5.83/6.01 6.69/7.06

20 11.00/11.67 17.23/16.99 25.77/23.49 31.89/29.22 35.94/32.40 37.73/34.24

21 11.28/17.44 18.31/24.50 27.85/33.35 35.04/40.68 39.97/44.61 42.09/46.75

22 11.62/14.98 16.14/22.44 24.33/31.46 31.20/39.27 34.20/43.54 35.90/45.79

23 4.00/3.62 4.89/4.51 7.52/6.20 9.42/8.26 10.60/9.62 11.83/10.73

24 3.84/2.51 4.24/3.05 5.71/4.30 6.86/6.09 7.64/7.32 8.55/8.38

25 6.66/6.81 8.00/8.40 11.45/11.07 13.96/13.68 15.59/15.26 17.26/16.48

26 3.35/2.72 4.19/3.82 6.75/5.64 9.01/7.94 10.41/9.47 11.98/10.63

27 26.58/21.18 31.76/27.40 40.17/35.80 46.80/42.19 50.02/45.49 51.58/47.44

29 0.95/1.43 1.63/2.37 3.01/3.92 5.35/6.13 7.09/7.63 8.41/8.77

30 3.37/3.86 4.44/4.85 5.70/6.66 8.11/8.82 9.31/10.22 10.69/11.35

31 0.74/1.96 1.83/2.72 3.53/4.15 5.54/6.17 7.06/7.55 8.09/8.65

32 2.47/4.08 3.18/5.27 4.10/7.30 6.75/9.63 7.85/11.14 8.80/12.30

33 5.60/5.33 8.07/7.52 11.30/10.62 14.46/13.85 16.26/15.82 17.50/17.16

34 8.59/11.59 13.99/17.92 20.21/25.54 26.29/32.42 29.34/36.26 31.00/38.33

35 12.46/14.09 18.87/21.17 25.10/29.75 31.76/37.25 35.15/41.36 36.92/43.55

36 15.46/16.89 23.84/22.90 33.21/30.72 40.59/37.09 44.52/40.49 48.81/42.45


11/14

0

10

20

30

40

50

60

0 10 20 30 40 50 60

Measured Cu(tot) Recovery, %

CalculatedCu(tot)Rec

overy,

10

Figure 4 - Comparison of measured and calculated Copper Recovery

insoluble (chalcopyrite) copper fraction, however, the results of the standard copper

mineralogical assay procedure indicated that the insoluble copper did leach under the typical

column leach test conditions and data from the commercial heap indicates that some

chalcopyrite is leached.

Once the recovery/time curve under the base case test conditions is determined for any

ore block, the recovery/time curve for the ore leached on the commercial heaps can beestimated based on the shrinking core model and a mass balance for the leach solution using

the computer program LEACH. This is accomplished by dividing the copper in the ore into

its acid soluble and cyanide soluble components, calculating the commercial heaps

recovery/time curve for each of the two components independently then adding the recoveries

for the two components together to obtain the recalculated recovery for the total ore. The

contribution of the chalcopyrite to the total recovery was estimated to be one percent per year

(i.e. 1 percent of the copper in the chalcopyrite would solubilized each year the ore was under

leach).

PROJECTION OF COMMERCIAL HEAP LEACHING RESULTS

The high numerical values of the adjusted correlation coefficients for the regression

equations imply that the recovery/time curves are almost completely and solely defined by the


12/14

11

copper mineralogy of the sample. Neither the ore zone from which the samples originated,

the degree of alteration of the ore nor the grade of the ore appears to have any measurable

influence on the recovery/time curve.

Operating parameters (as opposed to ore characteristics) for the column tests were

held constant. Particle size distributions, irrigation rates, column heights etc. were

intentionally kept very nearly constant in all tests. The affect of changes in these parameters

on the recovery/time curve can be calculated by the shrinking core model employed by the

computer program LEACH.

The constants generated by the regression analysis of the column test data physically

represent the recoveries of the copper in each of the three copper mineral groups: the acid

soluble fraction (copper oxides), the cyanide soluble fraction (secondary copper sulfides) and

insoluble fraction (chalcopyrite). The overall copper recovery from a column leach test is

found by taking a weighted average of these three curves. Given the recovery/time curves

in Figure 3, the leachabilities based on the shrinking core model of the acid soluble andcyanide soluble fractions of the copper in the ore were calculated using the computer program

LEACH. Once the leachabilities had been determined, the overall recovery/time curves

were calculated for commercial heaps using the operating parameters of the commercial heaps

and the computer program LEACH.

Simulation of the commercial heap operation give the following results:

The estimated recovery of the total contained copper in year 1 of leaching is:

% Recovery Cu(total) = 91.1 x S.I.(A.S.) + 49.9 x S.I.(CN sol.) (3)


% Recovery Cu(total) = 8.9 x S.I.(A.S.) + 8.3 x S.I.(CN sol.) (4)


% Recovery Cu(total) = 5.0 x S.I.(CN sol.) (5)


% Recovery Cu(total) = 3.3 x S.I.(CN sol.) (6)

The following points should be noted:

! All of the acid soluble copper is recovered in two years.

! The recoveries given are incremental recoveries: that is they are the


13/14

12

recovery for the year, not cumulative recoveries.

! The column test does not provide an estimate of the copper recovery from the

insoluble copper (chalcopyrite). This has been assumed to be 1 percent of

the copper in the chalcopyrite per year and was added to the above equations.

! The cumulative recovery for any number of years is found by summing the

coefficients of the equations for all the years over which the cumulative

recovery is desired.

Core samples of the La Caridad deposit have been collected and assayed for acid

soluble copper, cyanide soluble copper and total copper. A block model has been developed

from the these core samples. Equations 3 to 6, together with an appropriate present value

discount factor have been used to assign a value to each block for the copper that can be

recovered by heap leaching. Because of the correlation that has been developed between the

copper mineralogy and the copper recovery from heap leaching it is not necessary to run a

column leach test on every core sample.

CONCLUSIONS

This study resulted in three observations. First, the variation in response to leaching

of different La Caridad ore samples is primarily the result of variations in copper mineralogy

of the different ore samples. While the ultimate copper recovery of each ore sample is a

function of the percentage of the copper contained in the oxide and secondary sulfide

minerals, the rate of leaching is primarily a function of the ratio of oxide to secondary sulfide

minerals present. Other ore characteristics either have a minimal effect on the recovery/time

curve or their effects have been masked by the copper mineralogy.

Second, given a sufficient number of column leach tests the recovery/time curve can

be separated into individual recovery/time curves for the three forms of copper present in the

ore: oxide copper, secondary sulfide copper and primary sulfide copper. The recovery/time

curve for the individual copper components of the ore can be scaled up to the commercial

heap leaching operating parameters based on the shrinking core model. The projected overall

recovery/time curve for the commercial heap leaching operation is found to be the weighted

average of the recovery/time curves for these components. Once a sufficient number of

column leach tests have been conducted it is possible to construct a recovery/time curve for

any ore sample from the mineralogical assay of the sample: a column leach test is not needed.

Third, chalcopyrite appears to act initially as a preg robber precipitating copper from

the leach solution. This reaction converts the chalcopyrite to covellite, which eventually

dissolves, contributing to the copper production from the ore.


14/14

13

ACKNOWLEDGMENTS

The authors would like to acknowledge and thank the management of Mexicana de

Cobra and Mexicana de Cananea for there support during this project and their permission

to publish this paper. In addition we would like to thank the many other individuals at both

La Caridad and Cananea who participated in the experimental program and in discussions on

the column leach program and the plant operations.

REFERENCES

5. B.R. Benner and R.J. Roman, Determination of the Effective Diffusivity of H+ Ions

in a Copper Ore, AIME Transactions, VOL 256, 1974, 103 - 105. (Also seehttp://members.aol.com/leachinc/PUBLICATIONS.html )

6. R.J. Roman, B.R. Benner, and G.W. Benner, Diffusion Model for heap Leaching and

Its Application to Scale-Up, AIME Transactions, Vol 256, 1974, 247 - 252 (Also

see http://members.aol.com/leachinc/PUBLICATIONS.html )

7. G.A. Parkison and R.B. Bhappu, The Sequential Copper Analysis Method

geological, Mineralogical, and metallurgical Implications, paper presented at the

SME Annual Meeting, Denver, CO, USA, 6-9 March 1995, Preprint No. 95-90

(Also see http://members.aol.com/leachinc/CUMINERALS.html )

8. R.J. Roman, A Software Package for Heap Leaching, Presented at the Second

Canadian Conference on Computer Applications in the Mineral Industry, Vancouver,

B.C., 1991. (Also see http://members.aol.com/leachinc/Software.html )

PAPER_Interpretación Curvas Escalamiento

Documents

Transcript of PAPER_Interpretación Curvas Escalamiento