A method for extracting valuable metals from gold cyanide tailings

Abstract

The present invention relates to a method for extracting valuable metals from gold cyanide tailings, comprising the following steps: (1) adding water to the cyanide tailings to prepare cyanide tailings pulp and remove impurities; (2) activating the cyanide tailings pulp and removing cyanide; then adding alkali solution to adjust the pH value to 6.5-7.0; (3) adding a composite collector and mixing evenly, and then adding pine oil; (4) the treated pulp overflows to a flotation production device for flotation operation to obtain concentrate pulp and tailings pulp; (5) the concentrate pulp and tailings pulp are solid-liquid separated and dried to obtain iron concentrate and tailings. The present invention uses a flotation process and adds a composite collector to float and enrich FeS2 therein, so that the sulfur content of the ore reaches more than 46%, the iron content is increased to about 42%, the sulfur content of the tailings is reduced to about 5%, and the sulfur recovery rate reaches more than 92%. Sulfur concentrate utilization enterprises can use the sulfur resources therein to make sulfuric acid, and the acid slag iron concentrate after acid production meets the requirements of blast furnace ironmaking, so that sulfur and iron resources are fully utilized.

Description

Technical Field

[0001] The invention relates to a method for extracting valuable metals from gold cyanidation tailings, and belongs to the field of cyanidation tailings treatment. Background Art

[0002] Cyanide tailings are waste residues produced by my country's gold production enterprises. They contain unleached gold, silver, copper, lead, zinc, iron, sulfur, etc., and their grades are generally higher than the lowest industrial grade. They are an important secondary resource. Therefore, recovering valuable elements from cyanide tailings is of great significance to the realization of resource recovery.

[0003] Cyanide tailings have the following characteristics: (1) The mineral particle size is very fine. The gold concentrate required for the cyanide process has been fully ground and then re-ground in the cyanide process. Its particle size is already very fine. Data show that the content of copper, lead, zinc and other minerals -0.043mm in the tailings sometimes exceeds 95% (or even finer), and the specific surface area increases, presenting a "colloidal" dispersion system. As a result, it is obvious that the mineral muddy phenomenon is serious and flotation separation is difficult. (2) The floatability difference of non-ferrous metal minerals is small. The serious over-grinding of metal minerals, coupled with the dissolution of soluble sulfides and oxides under the long-term action of cyanide, has greatly changed the surface properties of the minerals, making them difficult to activate, and the floatability difference is significantly reduced. (3) During the cyanide gold extraction process, a hydrophilic calcium peroxide film will form on the surface of the mineral particles in the process of high alkalinity, rich oxygen and long-term immersion. The difference in surface electrical properties in the ore pulp makes it easier for metal sulfide ores to form calcium peroxide films than non-metallic gangue minerals. The formation of the film will not only cause the collector to lose its selectivity for mineral collection, but also affect the adsorption of the collector on the surface of the ore particles, resulting in a low flotation recovery rate for metal sulfide minerals. (4) The presence of a large amount of mud silicate minerals and residual sodium cyanide and other residual reagents in the ore pulp will have an adverse effect on the flotation process, ultimately resulting in low grade and recovery rate of copper, lead and zinc concentrates. (5) The mineral composition is relatively complex. The main minerals in the cyanide tailings are pyrite and chalcopyrite, followed by galena and sphalerite.

[0004] The main way to utilize cyanide tailings as hazardous waste is to supply sulfuric acid production enterprises with boiling roasting to produce sulfuric acid. Minerals with S content of 10% to 20% cannot be directly used to produce acid. In order to meet the requirements of production process and equipment, elemental sulfur needs to be added to increase the S content of tailings, meet the requirements of self-sufficient heat in boiling roasting production, and maintain a good boiling state. The addition of elemental sulfur will undoubtedly increase the cost of enterprises, and the iron content of sulfuric acid slag after acid production from lower-grade tailings is even lower, only about 25%. Although higher-grade ores with an average S content of 27-30% can meet the requirements of production process and equipment, the Fe content of the roasted sulfuric acid slag is low, only about 35%. The main use of sulfuric acid slag with low iron content is to supply cement plants as ingredients. With the utilization of domestic smelting slag, the market for sulfuric acid slag with low iron content is even more worrying. In the existing technology of activating and recovering pyrite from cyanidation tailings, such as in the patent of application number 202211376191.2, the activation and recovery method includes: (1) adding a reagent to the cyanidation tailings for mixing treatment to obtain a pulp; (2) activating the pulp obtained in step (1), and then flotation separation treatment to obtain pyrite. In the present invention, by pre-treating, activating and flotation separation the cyanidation tailings in sequence, the inhibitory effect of cyanide on pyrite can be eliminated, and its floatability can be restored to its original state and improved, thereby improving the recovery rate of pyrite, and the overall operation process is simple and convenient. Compared with the traditional activation flotation process, the recovery rate is increased by 30%. However, the overall process is complicated and the cost is high. Summary of the invention

[0005] The invention provides a method for extracting valuable metals from gold cyanidation tailings, which solves the problems of great difficulty in flotation of existing ultrafine cyanidation tailings and poor flotation effect.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A method for extracting valuable metals from gold cyanide tailings comprises the following steps:

[0008] (1) Adding water to the cyanide tailings to prepare a cyanide tailings slurry with a concentration of 35-45%, and removing impurities such as stone and sand therein;

[0009] (2) Activating the cyanide tailings slurry to remove cyanide; then adding alkali solution to adjust the pH value to 6.5-7.0;

[0010] (3) adding a composite collector and mixing evenly, and then adding pine oil to play a bubbling role, so that the slurry particles selectively adhere to the surface of the bubbles, wherein the composite collector comprises butyl xanthate, coupled modified oleic acid and zinc sulfate, and the weight ratio of the butyl xanthate: coupled modified oleic acid: zinc sulfate is 7:2.5:0.5;

[0011] (4) The treated slurry overflows to the flotation production device for flotation operation to obtain concentrate slurry and tailings slurry;

[0012] (5) The concentrate slurry and tailings slurry are separated into solid and liquid to obtain iron ore concentrate and tailings.

[0013] Further, preferably: the preparation method of the coupled modified oleic acid is specifically as follows: oleic acid, bentonite and silane coupling agent are uniformly mixed, 120°C, rotation speed 200r / min, react for 20min, then add polysilicate ferric sulfate, raise the temperature to 110°C, rotation speed 200r / min, react for 30min, and obtain coupled modified oleic acid.

[0014] Furthermore, preferably, the weight ratio of the oleic acid, bentonite, silane coupling agent and polysilicate ferric sulfate is 8:1:0.5:0.5.

[0015] Further, preferably: the activation of the cyanide tailings slurry is specifically performed by adding concentrated sulfuric acid, adjusting the pH value to 4.7-5, and reacting for 1-2 hours.

[0016] Further, preferably, the added amount of the composite collector is 350-400 g / t, and the added amount of pine oil is 60-80 g / t.

[0017] Further, preferably: the flotation is specifically: after the activation, the pulp first enters the primary roughing tank, and under the action of stirring and blowing, the FeS 2 The slurry particles float up with the bubbles, are scraped out by the scraper, and flow along the flow channel to the primary concentrator. Also, under the action of stirring and blowing, FeS 2 The slurry particles are further enriched and purified in the primary concentration tank, flow to the secondary concentration tank, and are scraped out with the scraper after further enrichment and purification, and flow into the concentrate slurry underground tank;

[0018] After the primary roughing, the pulp is sucked into the secondary roughing equipment through the gate channel between the flotation tanks under the action of the liquid level difference and the stirring and self-absorption of the flotation machine. Under the action of stirring and blowing, the FeS 2 The fine particles are scraped out and returned to the primary roughing equipment along the flow channel; the pulp after the secondary roughing enters the first and second sweep flotation tanks in turn to further recover FeS 2 The slurry particles are removed and the remaining slurry flows into the tailings slurry trough.

[0019] Beneficial effects of the present invention:

[0020] The present invention uses a flotation process to add a composite collector to separate FeS 2Flotation enrichment, the sulfur content of the ore reaches more than 46%, the iron content is increased to about 42%, the sulfur content of the tailings is reduced to about 5%, and the sulfur recovery rate reaches more than 92%. Flotation concentrate slurry filtration reduces the water content of the sulfur concentrate to less than 10%, which can be sold directly, reducing the turnover time and inventory of sulfur concentrate. Sulfur concentrate utilization enterprises can use the sulfur resources in sulfur concentrate to make sulfuric acid, and the acid slag iron concentrate after acid production meets the requirements of blast furnace ironmaking, so that sulfur and iron resources are fully utilized.

[0021] The mineral particle size in the cyanide tailings of the present invention is very fine, the mineral muddling phenomenon is serious, and flotation separation is difficult. (2) The difference in floatability of non-ferrous metal minerals is small. The serious over-grinding of metal minerals, coupled with the fact that soluble sulfides and oxides have been dissolved under the long-term action of cyanide, has greatly changed the surface properties of the minerals, making them difficult to activate, and the difference in floatability is significantly reduced. It is difficult to achieve a good flotation effect using a single collector. The present invention first modifies oleic acid. Oleic acid collectors have good hydrophobicity and relatively low cost, and have been widely used in the mining field, mainly in the flotation of non-sulfide minerals, especially in the flotation of minerals such as cassiterite, tungsten, antimony, lead, zinc and copper. Oleic acid collectors reduce the wettability of minerals by interacting with the mineral surface, allowing them to combine with bubbles during flotation and rise to the water surface to form foam. It can be seen that oleic acid is not suitable for the selection of sulfide minerals, but its good hydrophobicity has advantages for the flotation of ultrafine particles. The present invention modifies oleic acid by adding oleic acid, bentonite, silane coupling agent and polysilicate ferric sulfate to make it suitable for the flotation of ultrafine cyanide tailings.

[0022] Bentonite is a natural clay mineral with good adsorption and swelling properties. In the process of oleic acid modification, bentonite can improve the capture performance of oleic acid and enhance the adsorption of oleic acid on the mineral surface. In addition, bentonite can also improve the stability of oleic acid and improve the foam stability during flotation. Silane coupling agent is an organic silicon compound with good coupling effect. In the process of oleic acid modification, silane coupling agent can form chemical bonds with oleic acid and mineral surface, improving the capture performance and selectivity of oleic acid. At the same time, silane coupling agent can also improve the dispersibility of oleic acid and improve the dispersion stability during flotation. Polysilicate ferric sulfate is an inorganic polymer compound with good adsorption and stability. Polysilicate ferric sulfate aggregates fine tailing particles into larger flocs through flocculation, improves the foam stability during flotation, and is beneficial to the adsorption and flotation of oleic acid. At the same time, the iron ions in polysilicate ferric sulfate form stable complexes with oleic acid molecules, improving the capture performance and selectivity of oleic acid.

[0023] During the modification process of oleic acid, there is an interaction between bentonite, silane coupling agent and polysilicate ferric sulfate. Bentonite and silane coupling agent can improve the adsorption of oleic acid on the mineral surface, and polysilicate ferric sulfate can improve the stability of oleic acid. The three work together to achieve efficient capture and selective separation of oleic acid in ultrafine cyanide tailings flotation.

[0024] However, the use of a single modified oleic acid for the flotation of ultrafine cyanide tailings has the problems of high cost and poor flotation effect. Therefore, the present invention uses a combination of butyl xanthate: coupled modified oleic acid: zinc sulfate on the basis of modified oleic acid to flotate ultrafine cyanide tailings. The specific principle is as follows:

[0025] Butyl xanthate has a good collection ability for sulfide minerals such as chalcopyrite, but because the particles of cyanide tailings are relatively fine, butyl xanthate and cyanide tailings are not well combined, which in turn affects the flotation efficiency. The present invention adds coupled modified oleic acid, and the coupled modified oleic acid first reacts with the surface of the gangue mineral to form a protective film, which prevents the non-selective adsorption of butyl xanthate and allows butyl xanthate to be more selectively adsorbed on the target mineral; secondly, the oleic acid is modified to have flocculation properties, which can aggregate the fine tailings particles into larger flocs, reduce the solid content in the slurry, and improve the stability of the slurry. The use of the two together may achieve complementarity through different mechanisms of action, thereby improving the overall selectivity and recovery rate.

[0026] Zinc sulfate can form insoluble zinc cyanide with cyanide, thereby reducing the inhibitory effect of cyanide on pyrite. In addition, zinc sulfate can also form a stable complex with xanthate, enhancing the capture ability of xanthate on pyrite.

[0027] The three work together to enhance the hydrophobicity and selective adsorption of the mineral surface, improve the stability of the slurry, produce a synergistic effect, improve flotation efficiency and recovery rate, reduce the amount of reagents used, and reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 The process flow chart of the method of the present invention is shown in FIG. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The raw materials used in the following examples of the present invention are:

[0032] The cyanide tailings are provided by a gold refinery in Shandong. The main chemical components (mass fraction) of the cyanide tailings are Au 76g / t, Ag 23.65g / t, Pb 0.61%, Zn 0.53%, Cu 0.33%, S27.45%, Fe 26.41%, SiO 2 34.21%, Al 2 O 3 4.23%, CaO 3.21%, MgO 1.25%, Mn 0.067%, Ti 0.023%, K 2 O 1.03%, Na 2 O0.36%, As 0.13%, C 0.16%.

[0033] The particle size composition of cyanide tailings is as follows: particles less than 10 μm account for 33.62%, 10 μm-15 μm account for 35.12%, 15 μm-38 μm account for 28.65%, and particles greater than 38 μm account for 2.61%.

[0034] Butyl xanthate, pine oil and oleic acid, technically pure, commercially available.

[0035] Concentrated sulfuric acid, sodium hydroxide, sodium bentonite and silane coupling agent (KH550) were all commercially available and of analytical grade.

[0036] Polysilicate ferric sulfate, white powder, effective matter content 90%, commercially available.

[0037] The preparation method of the coupled modified oleic acid is as follows: oleic acid, bentonite and silane coupling agent are uniformly mixed, 120°C, rotation speed 200r / min, reaction for 20min, then polysilicate ferric sulfate is added, the temperature is raised to 110°C, rotation speed 200r / min, reaction for 30min, and coupled modified oleic acid is obtained. The weight ratio of oleic acid, bentonite, silane coupling agent and polysilicate ferric sulfate is 8:1:0.5:0.5.

[0038] The bentonite in the above preparation method is sodium-based bentonite, and the silane coupling agent is KH550.

[0039] like Figure 1As shown, a method for extracting valuable metals from gold cyanide tailings comprises the following steps:

[0040] (1) The raw material cyanide tailings are quantitatively transported to the material slurry through a plate feeder and a belt conveyor, and water is added to make a slurry with a mass concentration of 40-50%. The slurry passes through a spiral classifier and a screen to remove impurities such as stone and sand;

[0041] (2) The slurry after impurity removal enters the slurry tank, and then is quantitatively transported to the sealed four-stage activation tank by a vertical slurry pump. Concentrated sulfuric acid is added to the first-stage activation tank to control the pH value to 4.5-5.0, and the cyanide is broken by acidification. The slurry overflows to the second-stage activation tank, and is further acidified to break the cyanide. The slurry overflows to the third-stage activation tank, and alkali solution (sodium hydroxide) is added to the third-stage activation tank to adjust the pH value to 6.5-7 to provide a good pH value for the collector to function.

[0042] (3) Finally, the slurry overflows to the fourth-stage activation tank, and a composite collector is added to the fourth-stage activation tank to fully contact the material: the slurry overflowing from the fourth-stage activation tank directly flows into the flotation tank of the flotation section, and a foaming agent, pine oil, is added. Under the action of air blowing and stirring, the sulfur concentrate particles float up with the bubbles, while the vein ore particles flow to the other side at the bottom of the flotation tank:

[0043] (4) After self-activation, the slurry first enters the primary roughing tank. Under the action of stirring and blowing, FeS 2 The slurry particles float up with the bubbles, are scraped out by the scraper, and flow along the flow channel to the primary concentrator. Also, under the action of stirring and blowing, FeS 2 The slurry particles are further enriched and purified in the primary concentration tank, flow to the secondary concentration tank, and are scraped out with the scraper after further enrichment and purification, and flow into the concentrate slurry underground tank;

[0044] After the primary roughing, the pulp is sucked into the secondary roughing equipment through the gate channel between the flotation tanks under the action of the liquid level difference and the stirring and self-absorption of the flotation machine. Under the action of stirring and blowing, the FeS 2 The fine particles are scraped out and returned to the primary roughing equipment along the flow channel; the pulp after the secondary roughing enters the first and second sweep flotation tanks in turn to further recover FeS 2 The slurry particles are removed and the remaining slurry flows into the tailings slurry trough.

[0045] (5) Flotation obtains sulfur concentrate slurry and flotation tailings slurry, and then passes through a filter press for solid-liquid separation to obtain sulfur concentrate products and flotation tailings solid waste; the filter press wastewater flows into a circulating water pool for recycling and is not discharged externally; the activation tank waste gas is recovered in an organized manner and discharged after alkaline solution treatment.

[0046] Examples 1-5 Investigating the Effects of Different Collectors on Flotation

[0047] The composition of the collecting agent was adjusted to investigate the effects of different collecting agents on flotation. Concentrated sulfuric acid was added to control the pH value to 4.8. Sodium hydroxide lye was added to adjust the pH value to 6.7. The amount of collecting agent added was 400 g / t and the amount of pine oil added was 60 g / t. The specific data are shown in Table 1.

[0048] Table 1 Experimental results of the effects of different collecting agents on flotation

[0049]

[0050] As shown in Table 1, the present invention uses a combination of butyl xanthate: coupled modified oleic acid and zinc sulfate to effectively improve the recovery rate of sulfur, which is 93.62%, an increase of 36.97% compared to the single butyl xanthate, and an increase of 15.08 compared to the unmodified oleic acid. It can be seen that the present invention effectively improves the recovery rate of sulfur in ultrafine cyanidation tailings by optimizing the ratio of the collecting agent and modifying the oleic acid.

[0051] Examples 6-10 Investigate the effect of the amount of collecting agent added on flotation

[0052] The amount of collecting agent added was adjusted to investigate the effects of different addition amounts on flotation. Concentrated sulfuric acid was added to control the pH value to 4.8. Sodium hydroxide lye was added to adjust the pH value to 6.7. The amount of pine oil added was 60 g / t. The specific data are shown in Table 2.

[0053] Table 2 Experimental results of the effect of different addition amounts on flotation

[0054] 6 7 8 9 10 Addition amount of shrinking agent / (g / t) 330 350 380 400 420 Sulfur recovery rate / % 85.15 91.34 93.54 93.78 93.56

[0055] It can be seen from Table 2 that with the increase of the amount of sulfur recovery agent added, the sulfur recovery rate gradually increases. When the added amount is 380g / t, it has reached more than 93%. Then the sulfur recovery rate increases slowly. Therefore, the addition amount between 380-400g / t is more appropriate.

[0056] Examples 11-15 Investigate the effect of cyanide tailings of different particle sizes on flotation

[0057] Concentrated sulfuric acid was added to control the pH value to 4.8, sodium hydroxide lye was added to adjust the pH value to 6.7, the amount of the collector added was 380 g / t, the composite collector and butyl xanthate of the present invention were used, the amount of pine oil added was 60 g / t, and cyanide tailings with different particle sizes were used for flotation. The specific data are shown in Table 3.

[0058] Table 3 Flotation results of cyanide tailings with different particle size compositions

[0059]

[0060] As shown in Table 3, the method of the present invention has a very good flotation effect on cyanide tailings with different particle sizes, and the sulfur recovery rate is above 93%. In particular, for cyanide tailings with a particle size of less than 15 μm accounting for more than 70%, the muddiness is particularly serious. The sulfur recovery rate of butyl xanthate is about 60%, and the sulfur recovery rate of the present invention is above 93%, and the improvement rate is between 54.56-59.82%. It can be seen that the extraction method of the present invention has a very good flotation effect on ultrafine cyanide tailings.

[0061] Experimental example

[0062] The method of the present invention is adopted, concentrated sulfuric acid is added to control the pH value to 4.8, sodium hydroxide alkali solution is added to adjust the pH value to 6.7, the addition amount of the composite collecting agent is 380 g / t, the addition amount of pine oil is 60 g / t, 30 experiments are carried out, and the sulfur content and iron content of the obtained sulfur concentrate product are measured. The specific results are shown in Table 4.

[0063] Table 4 Sulfur concentrate product data determination results

[0064] Sulfur content / % Iron content / % Sulfur recovery rate / % Sulfur concentrate products 46.83±0.16 42.83±0.23 93.72±0.31 Cyanide tailings 27.45±0.18 26.41±0.24 Improvement rate / % 70.61±0.26 62.19±0.18

[0065] As can be seen from Table 4, the method of the present invention is stable and reliable. The sulfur content of the sulfur concentrate product is stably above 46%, the iron content is above 42%, and the S recovery rate is above 93%. Sulfur concentrate utilization enterprises can use the sulfur resources therein to produce sulfuric acid, and the acid slag iron concentrate powder after acid production can meet the requirements of blast furnace ironmaking, so that sulfur and iron resources can be fully utilized.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for extracting valuable metals from gold cyanide tailings, characterized in that: The following steps are involved: (1) Add water to the cyanide tailings to prepare a cyanide tailings slurry with a concentration of 35-45%, and remove the stone and sand impurities therein; (2) Activate the cyanide tailings slurry to remove cyanide; then add alkali solution to adjust the pH value to 6.5~7.0; (3) adding a composite collector and mixing evenly, and then adding pine oil to play a bubbling role, so that the slurry particles selectively adhere to the surface of the bubbles, wherein the composite collector comprises butyl xanthate, coupled modified oleic acid and zinc sulfate, and the weight ratio of the butyl xanthate: coupled modified oleic acid: zinc sulfate is 7:2.5:0.5; (4) The treated slurry overflows to the flotation production device for flotation operation to obtain concentrate slurry and tailings slurry; (5) Solid-liquid separation and drying of concentrate slurry and tailing slurry to obtain iron ore concentrate powder and tailings; The preparation method of the coupled modified oleic acid is specifically as follows: oleic acid, bentonite and silane coupling agent are uniformly mixed, heated at 120°C, rotated at 200r / min, reacted for 20min, then polysilicate ferric sulfate is added, heated to 110°C, rotated at 200r / min, reacted for 30min, and coupled modified oleic acid is obtained; The weight ratio of the oleic acid, bentonite, silane coupling agent and polysilicate ferric sulfate is 8:1:0.5:0.

5.

2. The method for extracting valuable metals from gold cyanide tailings according to claim 1, characterized in that: The activation of the cyanide tailings slurry is specifically performed by adding concentrated sulfuric acid, adjusting the pH value to 4.7-5, and reacting for 1-2 hours.

3. The method for extracting valuable metals from gold cyanide tailings according to claim 1, characterized in that: The added amount of the composite collector is 350-400 g / t, and the added amount of pine oil is 60-80 g / t.

4. The method for extracting valuable metals from gold cyanide tailings according to claim 1, characterized in that: The flotation is specifically as follows: the ore pulp treated in step (3) first enters a primary roughing tank, where, under the action of stirring and blowing, the ore pulp particles containing FeS2 float up with the bubbles, are scraped out by a scraper, and flow along the flow channel to the primary concentration tank; similarly, under the action of stirring and blowing, the ore pulp particles containing FeS2 are further enriched and purified in the primary concentration tank, flow to the secondary concentration tank, and after further enrichment and purification, are scraped out by a scraper and flow into the concentrate slurry underground tank; After the primary roughing, the pulp is sucked into the secondary roughing equipment through the gate channel between the flotation cells under the action of liquid level difference and self-priming of the flotation machine. Under the action of stirring and blowing, the FeS2 particles floating with the bubbles are scraped out and returned to the primary roughing equipment along the flow channel; the pulp after the secondary roughing enters the first and second sweep flotation cells in turn to further recover the FeS2 pulp particles, and finally the remaining pulp flows into the tailings slurry trough.

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