HK1071169B - Integration processes of the treatments of zinc silicate concentrates or zinc silicates ore and roasted concentrates of zinc sulphides - Google Patents

Description

Integrated process for treating concentrates of zinc silicate or zinc silicate ores and roasted concentrates of zinc sulfide

The present invention aims to provide a combined and unified process for the treatment of several calcines obtained from the calcination of sulphides with zinc silicate ores or concentrates, defined by the combination or combination of the diffusion of these several zinc sources, their filtration and the combined purification of the resulting zinc sulphate solution.

The well-known hydrometallurgical process for zinc production in solution is the treatment of sulphide calcines by neutral leaching in several leaching stages of ferrite followed by iron removal by jarosite, paragoethite, goethite, hematite deposition or as iron slag. GB 2114966A Recovery of Zinc from Sulphide materials, US 5120353 hydrometallurgical Method for processing raw material containing Zinc Sulphide, US 5585079 Method for leaching material oxide and silicate materials and Brazilian PI 9407223-0A process for extraction of Zinc from Sulphide Concentrates for the leaching of Zinc Sulphide and Zinc ferrite materials in combination are Processes for the leaching of Zinc from Sulphide Concentrates.

The result of these simplified process options is mainly an improvement in the recovery of zinc from silicate concentrates and ores (from 88% to 97% in zinc solution in the treatment of silicates).

The use of only one-step acid leaching of zinc ferrite is achieved by a combined process with silicate ores and concentrates, estimated to achieve 99.3% of the zinc solution relative to the zinc source.

The extraction of magnesium, a high content of chemical elements in zinc silicate ores and concentrates, is achieved using the magnesium treatment system described in all the combined operations. The invention also includes a method of scavenging undesirable elements, such as fluorides and chlorides, during zinc production.

The applicant has developed an integrated and unified process for the treatment of zinc silicate concentrates or zinc silicate ores and the calcination of zinc sulphide concentrates, characterized by the integrated leaching of a plurality of zinc sources, its filtration and the unique purification achieved. This association can be achieved in eight different ways:

(i) the integrated process is characterized in that in the neutral leaching process, zinc silicate raw ore or concentrate is used, provided from several ore sources, which are leached together with the calcine obtained by the calcination of the zinc sulphide, as illustrated in the flow chart of figure 1;

(ii) said combined process is characterized by the use of a concentrate of zinc silicate or zinc silicate ore in combination with the treatment of the calcine obtained by the calcination of the zinc sulphide in the ferrite or calcine acid leaching (7) process and in the iron deposition (11) process, as illustrated in the flow chart of figure 2;

(iii) said integrated process is characterized in that, after silicate leaching, in the neutral leaching stage (5), a concentrate of zinc silicate raw ore or zinc silicate ore, provided by several ore sources, is used in combination with the treatment of the calcine obtained by the calcination of the zinc sulphide, as illustrated in the flow chart of figure 3;

(iv) said integrated process is characterized by the selective deposition of zinc in magnesium treatment and integration with zinc sulphide calcine, in neutral leaching, ferrite acid leaching or iron deposition stages, using (obtained at 600-;

(v) said integrated process is characterized in that in the neutral leaching stage, which includes the removal of halogens, such as fluorides and chlorides, a concentrate of zinc silicate raw ore or zinc silicate ore, provided by several ore sources, is used, leached together with the calcine obtained by the calcination of the zinc sulphide, as shown in the flow chart of figure 5;

(vi) the integrated process is characterized by the use of zinc silicate raw concentrate or zinc silicate ore provided from several ore sources in combination with the treatment of the calcine obtained from the calcination of zinc sulphide in the acid leaching and iron deposition stages including the removal of halogens, such as fluorides and chlorides, as illustrated in the flow chart of figure 6;

(vii) the integrated process is characterized by the use of zinc silicate raw concentrate or zinc silicate ore provided from several ore sources in the neutral leaching stage after silicate leaching, including the removal of halogens, such as fluorides and chlorides, in combination with the treatment of the calcine obtained from the calcination of the zinc sulphide, as illustrated in the flow chart of figure 7;

(viii) the integrated process is characterized by the use of a zinc silicate concentrate or calcine of a zinc silicate ore (obtained at 600-.

The integrated process I-is shown in the block flow diagram of figure 1.

The combined method I-is shown in the block flow diagram of fig. 1.

Figure 1 shows a selection of the combined treatment process of a sulphide concentrate and a zinc silicate concentrate (or ore), where the combination or concatenation of the processes occurs in the neutral leaching stage (5). After magnesium treatment (2) of the silicate concentrate or ore, the silicate cake is pre-leached (4) in order to extract (4) the magnesium present in the concentrate and in the electrolytically used solution (13). In the preliminary leaching stage (4), the carbonates present in the concentrate are dissolved, and the acidic slurry is sent to neutral leaching (5) of the calcine (obtained by calcining the sulphide concentrate), where it is combined with a zinc extraction method of the two zinc sources combined. The operating conditions at each stage of this process are described below:

reslurry stage (1) -this stage consists of reslurrying the zinc silicate concentrate using the wash water of the leaching residue, plant residual water or only industrial water. In this stage of the process, the operating parameter is that the solids concentration is maintained at 45-60%. When highly acidic liquids are used, the repulping tank is coated with an acid resistant material to resist chemical attack.

Magnesium treatment stage (2) -the purpose of which is to remove the zinc silicate source and a part of the magnesium contained in the electrolytically used solution. It is advantageous to control the water balance of the device.

The spent solution produced in the zinc electrolysis stage is added to the ore slurry/zinc silicate concentrate so as to maintain the pH at 4.0-4.5. Direct or indirect steam was injected into the tank to maintain the temperature at 75-85 ℃. Under such conditions, a part of magnesium and a part of zinc contained in the silicate ore are added to the solution. Zinc is then selectively deposited over magnesium in a series of cascaded tanks by adjusting the pH parameters, temperature and residence time. When the concentration of zinc is less than 10.0 g/l, a solid/liquid separation is carried out, wherein the liquid is sent to the zinc recovery stage and the solid portion is sent to the pre-leaching stage of the ore or silicate concentrate.

The water balance of the device is achieved by using a certain amount of solution at this stage. When the water balance of the device is unfavorable (total volume increases), the amount of used solution fed to this stage is increased, whereas the favorable water balance causes the amount of used solution to decrease.

Pre-leaching stage (4) of the ore/silicate concentrate, which is a pre-leaching of the slurry, aimed at promoting the decomposition of the carbonates contained in the silicate ore/concentrate according to the following reaction:

MeCO₃+H₂SO₄→MeSO₄+CO₂+H₂o, where Me ═ Ca, Mg, Zn, and the like.

During this stage, the pH is maintained in the range of 3.0 to 3.5 by adding the spent solution produced by zinc electrolysis. The residence time is 3-6 hours and varies according to the physical and chemical characteristics of the silicate to be treated.

Neutral leaching stage (5) -a combination of processes occurs in this stage. Both ores (silicate ore and fully calcined zinc sulphide) are leached together. This leaching is carried out so as to obtain a maximum zinc extraction yield and coagulation of the silica, so as to allow the resulting slurry to be decanted, filtered or centrifuged. In order to obtain the maximum zinc extraction yield and coagulation of the silica, it has proved to be the most important among the several studied parameters:

pH value-3.2-3.8

-temperature-70-75 deg.C

-residence time: 4-5 hours

In this stage, the extraction of zinc was 80%.

The concentration of soluble silica in the zinc sulphate solution sent to purification was about 60-80 mg/l in the industrial test. This concentration of SiO does not impair or reduce the efficiency of the solid/liquid separation of the slurry.

However, in this stage, elements which are considered to be harmful for the zinc electrolysis stage are removed. This removal is accomplished by the deposition of the iron contained in the solution as ferric hydroxide. In this stage, chemical elements such As, Ge, Sb, Se, and Te are also removed. The iron in the first tank (tank) must be kept in the range of 0.5-3.0 g/l, which varies depending on the concentration of these elements considered to be harmful in the ore/concentrate being treated. The concentration of iron in the first tank is adjusted by using the liquid obtained in the acid leaching stage. Anode sludge containing magnesium dioxide is also added to the tank to bring Fe²⁺Is oxidized into Fe³⁺。

The slurry obtained in the last tank of the neutral leaching (7) is thickened in order to obtain an overflow containing zinc sulphate and traces of cadmium, copper, cobalt, nickel, arsenic, germanium, antimony, which is sent to purification, electrolysis and casting stages. These last stages of the process are not the subject of this patent.

The bottom liquor is fed to an acid leaching unit (7) for leaching zinc ferrite from the calcined calcine, these last stages also not being the subject of the present patent.

The integrated process II-is represented in the block flow diagram of figure 2.

Figure 2 shows another alternative of the process for connecting zinc sources. In this case, the binding occurs during the acid leaching (7) of the calcine and/or the iron deposition (11) phase, instead of during the neutral leaching phase of the previous option.

The amount of silicate concentrate or silicate ore in each stage may be 0-100%. The choice of using combination method I or II depends on:

whether the device is already operating: availability of equipment at each stage; complexity of layout changes; a matched physical space; cost/benefit.

If it is a new device: it depends more on cost/benefit.

The integrated approach III-is represented in the block flow diagram of fig. 3.

Figure 3 shows an integrated process for zinc production in which a silicate concentrate or ore is completely leached (4), and the resulting slurry is sent to neutral leaching of a calcine of a zinc sulphide concentrate (5).

In this process, a step called silicate leaching is introduced, followed by solid/liquid separation. Acidic leaching (4) of silicates is carried out with a solution called leaching solution, which is a mixture of concentrated sulphuric acid and a solution used for electrolysis. The concentration of acid in the leach solution may be 150-250 g/l, a variation due to sulfate equilibrium in the process. The residence time is 5-8 hours and depends mainly on the efficiency of the agitation in the tank, the particle analysis of the ore/concentrate, the temperature and the grade of the minerals contained in the zinc silicate source. The purpose of this stage is to extract as much zinc as possible from the silicate source, and the parameter for evaluating the efficiency of this stage is the amount of zinc dissolved in the acid discarded in the next stage, i.e. the solid/liquid separation (unleached zinc content). The value considered to be optimal is ZnH⁺Less than or equal to 0.5 percent. The two plant integrated process is completed by the liquids (14) obtained in the solid/liquid separation stage, which are sent to the neutral leaching (5). The conditions for the neutral leaching operation are the same as already described in the section "integrated process I". The solid residue obtained is sent to filtration (15) where it is washed in order to recover the soluble zinc.

The washing is carried out in two stages, namely repulping and replacement, and the soluble zinc content of the waste residue is less than 0.5%.

The combined method IV-is represented in the block flow diagram of fig. 4.

Figure 4 shows an integrated process, which has also been industrially tested and is intended for the roasting of silicate concentrates, aimed at decomposing the organic substances and carbonates contained in the concentrate. The calcination can be carried out by using any type of BPF oil, coal gas, natural gas, coal powder and the like in a horizontal or vertical batch kiln or a continuous kiln. The use of a pre-roasted silicate concentrate makes it possible to dispense with a preliminary silicate precipitation step, the purpose of which is to promote precisely the decomposition of the carbonates by chemical processes.

The combination of the methods can be achieved by:

-direct addition of the calcined silicate in the neutral leaching stage (5), or

-adding the calcined silicate in the acid leaching stage (7), or

-adding the silicate calcine in the iron/Paragoerite deposition stage (11), or

-adding the calcine of silicate simultaneously in the above two or three stages.

For all the options described above, the silicate calcine may or may not be subjected to magnesium treatment, in combination with other plant wash water or secondary filtrate of residue wash water, depending on the magnesium balance in the plant. Figure 4 shows the magnesium treatment in all options.

The operating conditions of the stages of addition of silicate ore/concentrate are the same as already described in the integrated processes I, II, III. The option of using calcined silicate ores/concentrates is made according to cost/benefit studies.

Figures 5-8 illustrate an integrated process and a process for removing halogens such as fluoride and chloride. They include an additional neutralization step, usually before the silicate leach slurry is filtered. The principle of fluoride removal is based on the formation of stable calcium fluoride (CaF) by deposition with lime₂) A compound having a pH of about 4.0 to 4.7. In this case, the pH is strictly controlled to not more than 5.0 in order to avoid zinc deposition and device yield reduction.

The following non-limiting examples of practical implementation of these methods are described below according to the present invention, the following data being taken from small-scale experiments and/or industrial-scale practices:

example 1

Combination procedure III:

using integrated process III to increase recovery of the plant

The concentrate is processed according to the flow diagram of fig. 3.

Treatment capacity:

-sulfide concentrate 10212.332 ton

-silicate concentrate 13291.000 tons

The leaching efficiency of the silicate concentrate is 94.30%

The content of zinc soluble in acid is 1.79%

Net height in the concentrate of leached silicate concentrate 1.4 m

The consumption of zinc powder was 2.94% relative to the produced cathode material

The yield of cathode material was 9641.430 tons

Problems with this approach:

since silicate concentrates are produced by flotation, during the use of this process, significant foaming occurs during leaching and overflow of the tank occurs. One way to reduce this overflow is to perform a weak leach, use more reactors and use a local pump to return the overflow to the original tank. Another solution to this problem is the combined method IV.

When the total content of organic substances exceeds 3 mg/liter, the current efficiency (faraday) decreases. Controlling this parameter in the silicate mineral beneficiation plant, more accurately controlled in flotation depletion or integrated process IV (fig. 4) implementation.

Combination method IV:

at the end of the hot acid leaching, the calcined silicate concentrate is added to increase the leaching efficiency of the zinc silicate calcined concentrate and to increase the leaching efficiency of the calcine of the sulphide concentrate.

Method IV was tested on a bench, small scale and commercial set-up (FIG. 4). The results obtained were as follows:

results obtained in a small scale apparatus (examples 2-8):

example 2

Calcination of zinc silicate concentrate

Figure 9 shows the results of a comparison of the calcined concentrate at 900 c with the original concentrate regarding loss on ignition, zinc content, carbonate content and foam formation. Figure 9 shows that in pilot or industrial trials it is possible to eliminate the froth completely with a reduction in mass (loss on ignition) of 20%, which refers to a reduction in carbonate (< 0.2%) and moisture, as the zinc content in the concentrate increases from 40% to 44% (based on the calcined concentrate).

Example 3

Effect of calcination in existing methods of Magnesium Treatment (MT)

Figure 10 shows the results of a zinc selective deposition test of a calcined silicate concentrate whose zinc-containing solution contains 17 grams per liter of zinc and 2.1-2.4 grams per liter of magnesium. The results demonstrate that zinc is deposited to 2.7-4.3 g/l at a temperature of 90-95 ℃ and a residence time of 5 hours, which indicates an efficiency of about 80% (17-4/17X 100) for zinc deposition, while the magnesium concentration increases from 2.4 to 4.0 g/l, indicating a significant magnesium scavenging capacity.

Example 4

Effect of calcination on silicate leaching

Figure 11 shows that calcination of the silicate concentrate during leaching results in a significant reduction in residence time, from 4 hours to 1.5 hours, due to the reduced foam generation. This makes it possible to reduce the volume necessary to carry out the zinc source leaching.

Example 5

Effect of calcination on Zinc sulfate solution purification

Figure 12 shows the effect of calcination on zinc sulphate solution purification and when the solution is made from calcined concentrate, the zinc powder consumption is reduced by more than 1% and from 4.12% to 2.95% relative to the resulting cathode.

Example 6

Leaching and filtration efficiency of zinc sulfide calcine

Figure 13 shows the leaching and filtration efficiency of zinc sulphide calcine, which increased from 96% to 99% at the end of acid leaching or at the beginning of iron deposit neutralisation, depending on the results obtained with the calcined silicate ore/concentrate feed. The tests were carried out on a 50 liter bench set-up under the operating conditions outlined in FIG. 13.

Example 7

Effect of neutralization on fluoride content reduction in Zinc sulfide

The results of bench tests for silicate concentrate leaching to reduce fluoride content can be found in figure 14.

Results obtained in Industrial Scale experiments (examples 8 to 10)

Calcination of silicate concentrate in rotary kiln

The temperature is 600 ℃ and 900 DEG C

The residual content of carbonate is 2% or the total carbon is 0.3% at the maximum

Fig. 15 shows the results of a combined industrial trial demonstrating the performance of the selective deposition of zinc which has been shown in fig. 10. The figure shows that in the liquid part of the solution, the zinc content is typically 5 g/l on average when a washing liquid and silicate concentrate of Zn 17-25 g/l are used for the selective deposition of zinc.

Example 9

Figure 16 shows the results of a commercial test using a calcined silicate concentrate and the integrated process of figure 4. The average leaching and filtration efficiencies achieved are 95-99%, and the major obstacle to maintaining high efficiency is that low efficiency filter presses are used to extract the water soluble zinc.

Example 10

Reducing fluoride content in zinc sulfide solution from silicate concentrate

Figure 17 shows the results of an industrial trial for the removal of fluoride from the solution obtained from silicate concentrate leaching.

It was found that the content decreased from 27 mg/l to 17 mg/l, which allowed for automatic removal at electrolysis.

Claims (15)

1. An integrated process for treating a concentrate or ore of zinc silicate and a roasted concentrate of zinc sulphide, characterized in that: the combination occurs in

-a neutral leaching stage (5) comprising a fluoride and chloride removal stage, characterized in that in the neutral leaching stage (5) there is used a raw zinc silicate concentrate or ore obtained from several ore sources, which is leached together with a calcined zinc sulphide calcine; or

-an acid leaching (7) and iron precipitation stage (11) including a fluoride and chloride removal stage, characterized in that in the acid leaching (7) and iron precipitation (11) there is used a zinc silicate raw concentrate or ore of several mineral sources in combination with the treatment of the calcine obtained by the calcination of zinc sulphide; or

-neutral leaching (5) after silicate leaching (4), including stages for removing fluorides and chlorides, characterized in that after the leaching stage (4) of the silicate concentrate or ore, in neutral leaching (5) several mineral-derived zinc silicate ores or concentrates are used, combined with the treatment of the calcine obtained by zinc sulphide calcination.

2. Integrated process for the treatment of concentrates or ores of zinc silicates and roasted concentrates of zinc sulphides according to claim 1, characterized by the fact that the principle of fluoride removal is based on the precipitation with lime.

3. Integrated process for the treatment of concentrates or ores of zinc silicates and roasted concentrates of zinc sulphides according to claim 1 characterized by the fact of comprising a repulping stage (1) in which the concentrates of zinc silicates are repulped with water washed with leaching residues, residual water or industrial water.

4. Integration processes according to claim 3, characterized in that in the repulping stage (1) the solids concentration is maintained between 45 and 60% by mass.

5. Integrated process for the treatment of concentrates or ores of zinc silicates and roasted concentrates of zinc sulphides according to claim 1, characterized by the fact that it comprises a magnesium treatment stage (2) in which the zinc-electrolytically spent solution is added to the zinc silicate concentrate or ore slurry in order to maintain the pH between 4.0 and 4.5, said magnesium treatment stage (2) being aimed at removing the source of zinc silicate and a part of the magnesium contained in the electrolytically spent solution.

6. Integrated process for the treatment of concentrates or zinc silicates ore and roasted concentrates of zinc sulphides according to claim 5, characterized in that in the magnesium treatment stage (2) water vapour is injected directly or indirectly into the tank for the magnesium treatment stage in order to maintain the temperature between 75 and 85 ℃.

7. Integrated process for the treatment of concentrates or zinc silicates ore and roasted concentrates of zinc sulphides according to claim 1 characterized by the fact that when the zinc concentrate is below 10.0 g/l, a solid/liquid separation is carried out, the liquid being sent to the zinc recovery stage and the solids being sent to the preliminary leaching stage (4) of the silicate ore or concentrate.

8. Integrated process for the treatment of concentrates or zinc silicates or ores and roasted concentrates of zinc sulphides according to claim 7, characterized in that the pH value in the pre-leaching (4) of the silicate ores or concentrates is maintained between 3.0 and 3.5 by the addition of the used solution produced by zinc electrolysis.

9. Integrated process for the treatment of concentrates or zinc silicates or ores and roasted concentrates of zinc sulphides according to claim 7, characterized in that the residence time in the pre-leaching (4) of the silicate ore or concentrate varies between 3 and 6 hours.

10. Integrated process for the treatment of concentrates or ores of zinc silicates and roasted concentrates of zinc sulphides according to claim 1, characterized by the fact that in neutral leaching (5) the pH is between 3.2 and 3.8; the temperature is 70-75 ℃; and the residence time is 4-5 hours.

11. Integrated process for the treatment of concentrates or ores of zinc silicates and roasted concentrates of zinc sulphides according to claim 1, characterized in that the leaching stage (4) of the concentrates or ores of silicates comprises a solution called etching solution, which is a mixture of concentrated sulphuric acid mixed with or not mixed with the solution used for electrolysis.

12. Integrated process for the treatment of concentrates or ores of zinc silicates and roasted concentrates of zinc sulphides according to claim 11, characterized in that the acid concentration in the etching solution is 150-250 g/l.

13. Integrated process for the treatment of concentrates or ores of zinc silicates and roasted concentrates of zinc sulphides according to claim 1, characterized in that the leaching stage (4) of the concentrates or ores of silicates comprises a residence time of 5-8 hours.

14. Integrated process for the treatment of concentrates or ores of zinc silicates and roasted concentrates of zinc sulphides according to claim 1, characterized in that it comprises, after the leaching (4) of concentrates or ores of silicates or calcines of silicates, a solid/liquid separation stage (14), the solid residue obtained being sent to a filtration (15) where it is washed in order to recover the soluble zinc.

15. Integrated process for the treatment of concentrates or ores of zinc silicates and roasted concentrates of zinc sulphides according to claim 14, characterized in that the washing is carried out in two stages, i.e. repulping and substitution, and the content of soluble zinc contained in the reject residue is less than 0.5%.