A method for pre-treating and removing impurity elements from complex gold concentrate

Abstract

The present invention belongs to the technical field of non-ferrous metal pyrometallurgy, and specifically relates to a method for pre-treatment removal of impurity elements in complex gold concentrates. The pyrometallurgical pre-removal method for impurity elements in complex gold concentrates provided by the present invention has good impurity removal effect, can effectively separate antimony and arsenic elements, has a short process flow, is environmentally friendly and does not affect the subsequent smelting process. The present invention adopts copper oxide as an oxidant, so that the impurity removal process will not introduce other impurity elements. In addition, in the subsequent gold capture process, complex gold concentrate and copper concentrate will be mixed to make matte for gold capture. The method of the present invention includes the steps of mixing, smelting, secondary mixing, vacuum oxidation, gasification and the like. By adopting the method of the present invention, arsenic and antimony elements in complex gold concentrates can be effectively removed by sulfidation-vacuum oxidation-vacuum gasification. The method of the present invention has the advantages of high impurity removal efficiency, short production process, simple operation, high degree of automation, low production cost and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of nonferrous metal pyrometallurgy, and particularly relates to a method for pre-treating and removing impurity elements in complex gold concentrate. Background Art

[0002] In recent years, high-grade gold concentrate resources have gradually decreased, while low-grade gold concentrate with more complex composition has gradually become the main source of precious metals. Low-grade gold concentrate with more complex composition often contains impurities such as antimony and arsenic, making it difficult to process.

[0003] During the pyrometallurgical smelting of gold concentrate, the impurity element arsenic can significantly change the resistance of the dust collection system's bag filters. The volatilization of arsenic and its compounds can also easily cause secondary combustion, leading to coking. Furthermore, after pyrometallurgy, some arsenic and antimony accumulate in the copper anode plates. Because these impurities have a similar potential to copper, they enter the electrolyte during the electrolysis process. Most of these elements then hydrolyze into solid oxides and enter the anode mud. This not only reduces the quality of the cathode copper and anode mud, but also causes scaling in the circulating pipes.

[0004] The treatment of impurity elements such as arsenic and antimony in gold ores is well documented in the prior art. For example, Chinese patent publication number CN106319199A discloses a method for pretreating refractory gold ores containing antimony and arsenic. This method primarily addresses the problem that, when using existing roasting and oxidation methods to treat antimony- and arsenic-containing gold ores, antimony readily forms nonvolatile antimony salts that cannot be completely removed, preventing economic utilization of antimony. Furthermore, large amounts of toxic and harmful gases such as As2O3, SO2, and Sb2O3 are generated in the flue gas, easily causing environmental pollution. The method disclosed in this patent achieves efficient removal of antimony by crushing and ball-milling the refractory gold ores containing antimony and arsenic, followed by roasting. However, this method cannot achieve separate treatment of arsenic volatiles and antimony, and the treatment effect needs to be improved.

[0005] To reduce the impact of impurities on the smelting of complex gold concentrates, a process combining beneficiation with traditional wet alkaline or acid leaching can be used prior to pyrometallurgy to remove impurities. This method can achieve impurity removal rates exceeding 85%. However, the complex mineral raw materials make it difficult to effectively remove elements such as arsenic and antimony from the gold concentrate during beneficiation. Impurities are trapped within the ore, leading to instability in the beneficiation and leaching processes and significant variability in the composition of the incoming charge. Wet leaching is characterized by a lengthy process, complex operations, high labor intensity, high material loss, and the discharge of large volumes of difficult-to-treat wastewater and liquids. Furthermore, during acid leaching, the leachate has high iron and chloride ion concentrations and high solution viscosity, making slag filtration and washing difficult. Acid leaching also presents challenges such as high equipment corrosion requirements, poor leaching selectivity, and the tendency for the solution to explode during the subsequent electrolytic deposition process. During alkaline leaching, large amounts of alkali salts enter the ore and participate in the pyrometallurgical process, causing alkaline slag to corrode the furnace lining and significantly shorten the life of the smelter. At the same time, there are disadvantages such as serious accumulation of sodium salts such as sodium sulfide in the cycle, large and cumbersome waste liquid treatment volume, and low current efficiency and high power consumption in the subsequent electrolytic process.

[0006] Based on this, the present invention intends to develop a method for pre-treatment and removal of impurity elements in complex gold concentrates. By effectively removing elements such as antimony and arsenic before pyrometallurgical smelting of gold concentrates, the requirements for the content of arsenic and antimony elements in the smelting process can be met, in order to reduce the impact on subsequent processes. Summary of the Invention

[0007] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a method for pre-removing impurity elements from complex gold concentrates by pyrometallurgical method, which has good impurity removal effect, can effectively separate antimony and arsenic elements, has a short process flow, is environmentally friendly and does not affect the subsequent smelting process. The process method has the advantages of short production flow, simple operation, high degree of automation and low production cost.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for pre-treating and removing impurity elements from complex gold concentrate comprises the following steps:

[0010] (1) Sulfur is used as material A, and complex gold concentrate is used as material B. Material A and material B are ground separately and uniformly mixed to obtain a mixed material C;

[0011] (2) placing the mixed material C in a vacuum furnace, removing air and introducing protective gas, then heating it to a preset smelting temperature and keeping it at that temperature for a certain period of time for smelting; after smelting, wait for the temperature in the furnace to drop to room temperature, and collect the residue D and volatile matter E;

[0012] (3) Grinding the oxidant as material F and the residue D obtained in step (2) separately, and then uniformly mixing them to obtain a mixed material G;

[0013] (4) placing the mixed material G in a vacuum furnace and evacuating the temperature to 5Pa-50Pa; then heating it to a preset oxidation temperature and keeping it warm for a certain time for vacuum oxidation, and then heating it again to a gasification temperature and keeping it warm for a certain time for vacuum gasification; after gasification, wait for the temperature in the furnace to drop to room temperature, and take out the residue H and volatile matter I; the obtained residue H is the gold concentrate after impurities are removed.

[0014] Specifically, the impurity elements and their mass percentages in the complex gold concentrate in step (1) are: As 1%-8%, Sb 2%-10%.

[0015] Specifically, the amount of material A added in step (1) is 0.03-0.08 times the mass of material B; preferably, 3-8 g of sulfur is used as material A and 100 g of complex gold concentrate is used as material B in step (1).

[0016] Specifically, in step (2), during smelting, the protective gas introduced is nitrogen, argon or helium, preferably nitrogen; and the introduction flow rate is 50-150 ml / min.

[0017] Specifically, in step (2), during smelting, the smelting temperature is 250-450°C; and the heating rate is 20-50°C / min.

[0018] Specifically, in step (2), during smelting, the smelting time is 30-120 minutes.

[0019] Specifically, in step (3), the oxidant is copper oxide or lead tetroxide.

[0020] Specifically, in step (3), the amount of material F added is 0.1-0.5 times the mass of the residue D.

[0021] Specifically, in step (4), the heating rates are both 20-50°C / min.

[0022] Specifically, during the vacuum oxidation process in step (4), the oxidation temperature is 500-1000° C. and the oxidation time is 30-120 min.

[0023] Specifically, during the vacuum vaporization process in step (4), the vaporization temperature is 700-1100° C., and the vacuum vaporization temperature is higher than the vacuum oxidation temperature; and the vaporization time is 30-120 min.

[0024] The present invention uses a process of sulfidation-vacuum oxidation-vacuum vaporization to effectively enrich arsenic and antimony in volatile matter in the form of sulfides and oxides, respectively, facilitating the separation of arsenic, antimony, and gold concentrate and their subsequent disposal in the recovery process. The reaction principle is as follows:

[0025] S8 (g) + 16 / 9Sb2O3 = 16 / 9Sb2S3 + 8 / 3SO2 (g)

[0026] S8 (g) + 16 / 9As2O3 = 16 / 9As2S3 + 8 / 3SO2 (g)

[0027] Sb2S3+3CuO=3CuS+Sb2O3

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The method of the present invention can effectively remove arsenic and antimony from complex gold concentrates through a process of sulfidation-vacuum oxidation-vacuum vaporization. Specifically, during the pretreatment process, arsenic and antimony are converted into sulfides through sulfidation at a certain temperature. The arsenic is then volatilized and separated based on the different volatilization temperatures of the arsenic and antimony sulfides. Antimony sulfides are then converted into low-valent oxides through oxidation at a certain temperature. The antimony is then vaporized and volatilized under vacuum conditions, separating it from the gold concentrate.

[0030] 2. The present invention uses copper oxide as an oxidant, preventing the introduction of other impurities during the impurity removal process. Furthermore, in the subsequent gold capture process, a mixture of complex gold concentrate and copper concentrate is used to produce matte for gold capture. The addition of copper oxide not only eliminates the impact of the oxidant on subsequent processes but also helps improve the grade of copper matte produced in the gold capture process. Therefore, the addition of copper oxide also facilitates the subsequent three-stage continuous furnace fire-process for gold capture from complex gold concentrate.

[0031] 3. Pretreatment to remove impurity elements from complex gold concentrates can meet the smelting requirements for arsenic and antimony content during the smelting process, allowing direct entry into the pyrometallurgical gold capture process. The pretreatment and impurity removal method of the present invention provides an excellent approach for reducing coking, lowering the impurity content of anode mud, improving cathode plate quality, and ensuring smooth gold capture. The method of the present invention has a short process flow, high impurity element (arsenic and antimony) removal rate, simple operation, and environmental friendliness.

[0032] 4. The method of the present invention has a friendly process flow and is suitable for industrial promotion; it has the advantages of high impurity removal efficiency, short production process, simple operation, high degree of automation, and low production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a process flow chart of the present invention;

[0034] Figure 2 The ratio of the amount of As and Sb removed in the two volatilization processes of step (2) and step (4) in Examples 1, 2, and 3 of the present invention to the As and Sb in the complex gold concentrate raw material. DETAILED DESCRIPTION

[0035] The following examples are implemented on the premise of the technical solution of the present invention, and provide detailed implementation plans and specific operating processes, but the protection scope of the present invention is not limited to the following examples.

[0036] Example 1

[0037] A method for pre-treating and removing impurity elements from complex gold concentrates, the process flow of the method is as follows Figure 1 As shown, the specific process steps are:

[0038] (1) Take 3g of sulfur (sulfur element, sulfur content 99%, AR reagent) as material A, and take 100g of complex gold concentrate (a gold concentrate raw material prepared by flotation of primary gold ore composed of pyrite, arsenopyrite, stibnite, quartz and feldspar) as material B, grind the two and mix them evenly to obtain a mixed material C; Example 1 selects a complex gold concentrate with an As content of 4.65wt% and an Sb content of 5.83wt% as the impurity-removing raw material (i.e., material B), and the specific element contents are shown in Table 1;

[0039] (2) The mixed material C is placed in a crucible, and then placed in a vacuum furnace with a condensation system, and nitrogen is introduced at a flow rate of 50 ml / min until the furnace temperature cools to room temperature; then the temperature is raised to 250°C at a rate of 20°C / min, and the temperature is kept for 30 minutes for smelting; wherein, the condensation system includes a condensation tank, a condensation cover and a tray; a condensation pipe is provided in the inner plate of the condensation tank, the inlet end of the condensation pipe is connected to the exhaust port of the vacuum furnace through an air guide pipe, and a liquid outlet pipe is provided at the outlet end of the condensation pipe; the condensation cover is provided above the tray, and the end of the liquid outlet pipe extends into the gap between the condensation cover and the tray; the condensation system described in the present invention can adopt commonly used equipment in the prior art, and its structure is not the inventive point of the present invention, so it will not be described in detail;

[0040] During the smelting process, a solid product is obtained in the crucible. The volatile components during smelting enter the condensation system through the exhaust port of the vacuum furnace, and finally fall into the tray after condensation.

[0041] After the insulation is completed and the temperature in the furnace drops to room temperature, the residue D in the crucible and the volatile matter E in the tray are taken out;

[0042] (3) 10 g of the oxidant was taken as material F, and the residue D (98.13 g) and material F were ground and mixed uniformly to obtain a mixed material G; wherein the oxidant was copper oxide;

[0043] (4) The mixed material G (108.13 g) was placed in a crucible and placed in a vacuum furnace with a condensation system (the condensation system is the same as above), and the vacuum was evacuated to 5 Pa and the vacuum was maintained; the temperature was then raised to 500°C at a rate of 20°C / min and kept warm for 30 minutes for vacuum oxidation; the temperature was then raised at a rate of 20°C / min, and when the temperature reached 700°C, the temperature was stopped and kept warm for 30 minutes for vacuum gasification; after the insulation was completed, the furnace door was opened to cool down, and after the temperature in the furnace dropped to room temperature, the residue H in the crucible and the volatile matter I in the tray were taken out; the residue H obtained in the crucible was the gold concentrate after impurities were removed.

[0044] The proportions of the elements in the residue H are shown in Table 2. The arsenic and antimony elements in the volatiles E and I prepared in Example 1 were subjected to XRF testing. The results are as follows: Figure 2 As shown, after calculation and analysis, it was found that the arsenic removal rate of the gold concentrate in step (2) was 36.1%, and the antimony removal rate was 4.4%; the arsenic removal rate of the gold concentrate in step (4) was 46.5%, and the antimony removal rate was 75.9%; the total arsenic removal rate of the gold concentrate was 82.6%, and the total arsenic removal rate was 80.3%.

[0045] Example 2

[0046] A method for pre-treating and removing impurity elements from complex gold concentrates, the process flow of the method is as follows Figure 1 As shown, the specific process steps are:

[0047] (1) Take 5g of sulfur (sulfur element, sulfur content 99%, AR reagent) as material A, and then take 100g of complex gold concentrate (a gold concentrate raw material prepared by flotation of primary gold ore composed of pyrite, arsenopyrite, stibnite, quartz and feldspar) as material B, grind the two and evenly mix them to obtain a mixed material C; Example 2 selects a complex gold concentrate with an As content of 6.73wt% and an Sb content of 3.14wt% as the impurity-removing raw material (i.e., material B), and the specific element contents are shown in Table 1;

[0048] (2) Mixed material C was placed in a crucible, which was then placed in a vacuum furnace equipped with a condensation system, and nitrogen was introduced at a flow rate of 70 ml / min until the furnace temperature cooled to room temperature;

[0049] The temperature was then raised to 350°C at a rate of 30°C / min and held at that temperature for 90 minutes for smelting. After the holding period, the temperature in the furnace was lowered to room temperature, and the residue D in the crucible and the volatile matter E in the tray were removed. The condensation system in Example 2 was the same as that in Example 1.

[0050] (3) 20 g of the oxidant was taken as material F, and the residue D (98.69 g) and material F were ground and mixed uniformly to obtain a mixed material G; wherein the oxidant was copper oxide;

[0051] (4) The mixed material G (118.69 g) was placed in a crucible and placed in a vacuum furnace with a condensation system (the condensation system was the same as in Example 1), evacuated to 10 Pa, and the vacuum was maintained; then the temperature was raised to 800°C at a rate of 30°C / min and kept warm for 90 minutes for vacuum oxidation; then the temperature was raised at a rate of 30°C / min, and when the temperature reached 900°C, the temperature was stopped and kept warm for 90 minutes for vacuum gasification; after the insulation was completed, the furnace door was opened to cool down, and after the temperature in the furnace dropped to room temperature, the residue H in the crucible and the volatile matter I in the tray were taken out; the residue H obtained in the crucible was the gold concentrate after impurities were removed.

[0052] The proportions of various elements in the residue H are shown in Table 2. The arsenic and antimony elements in the volatiles E and I prepared in Example 2 were subjected to XRF testing. The results are as follows: Figure 2 As shown, after calculation and analysis, it was found that the arsenic removal rate of the gold concentrate in step (2) was 95.3%, and the antimony removal rate was 9.7%; the arsenic removal rate of the gold concentrate in step (4) was 2.6%, and the antimony removal rate was 86.8%; the total arsenic removal rate of the gold concentrate was 97.9%, and the total arsenic removal rate was 96.5%.

[0053] Example 3

[0054] A method for pre-treating and removing impurity elements from complex gold concentrates, the process flow of the method is as follows Figure 1 As shown, the specific process steps are:

[0055] (1) 8 g of sulfur (sulfur element, sulfur content 99%, AR reagent) was taken as material A, and 100 g of complex gold concentrate (a gold concentrate raw material prepared by flotation of primary gold ore composed of pyrite, arsenopyrite, stibnite, quartz and feldspar) was taken as material B, and the two were ground and uniformly mixed to obtain a mixed material C; Example 3 selected a complex gold concentrate with an As content of 6.88 wt% and an Sb content of 8.22 wt% as the impurity-removing raw material (i.e., material B), and the specific element contents are shown in Table 1;

[0056] (2) Mixed material C was placed in a crucible, which was then placed in a vacuum furnace equipped with a condensation system, and nitrogen was introduced at a flow rate of 150 ml / min until the furnace temperature cooled to room temperature;

[0057] The temperature was then raised to 450°C at a rate of 50°C / min and held at that temperature for 120 minutes for smelting. After the holding period, the temperature in the furnace was allowed to drop to room temperature, and the residue D in the crucible and the volatiles E in the condensation tray were removed. The condensation system in Example 3 was the same as that in Example 1.

[0058] (3) 50 g of the oxidant was taken as material F, and the residue D (97.96 g) and material F were ground and mixed uniformly to obtain a mixed material G; wherein the oxidant was copper oxide;

[0059] (4) The mixed material G (147.96 g) was placed in a crucible and placed in a vacuum furnace with a condensation system (the condensation system was the same as in Example 1), evacuated to 50 Pa, and the vacuum was maintained; then the temperature was raised to 1000°C at a rate of 50°C / min and kept warm for 120 minutes for vacuum oxidation; then the temperature was raised at a rate of 50°C / min, and when the temperature reached 1100°C, the temperature was stopped and kept warm for 120 minutes for vacuum gasification; after the insulation was completed, the furnace door was opened to cool down, and after the temperature in the furnace dropped to room temperature, the residue H in the crucible and the volatile matter I in the tray were taken out; the residue H obtained in the crucible was the gold concentrate after impurities were removed.

[0060] The proportions of various elements in the residue H are shown in Table 2. The arsenic and antimony elements in the volatiles E and I prepared in Example 2 were subjected to XRF testing. Figure 2 As shown, after calculation and analysis, it was found that the arsenic removal rate of the gold concentrate in step (2) was 72.6%, and the antimony removal rate was 11.3%; the arsenic removal rate of the gold concentrate in step (4) was 12.5%, and the antimony removal rate was 72.4%; the total arsenic removal rate of the gold concentrate was 85.1%, and the total arsenic removal rate was 83.7%.

[0061] Table 1 Element content of complex gold concentrate in each embodiment

[0062]

[0063] Table 2 Element contents of residue H after impurity removal in each embodiment

[0064]

[0065]

[0066] In summary, the present invention utilizes the sulfidation-vacuum oxidation-gasification method to remove As and Sb from complex gold concentrates: under sulfidation conditions, a large amount of arsenic and other impurity elements are removed; under vacuum conditions, the impurity elements are oxidized by adding an oxidant, and then a large amount of antimony and other impurity elements are removed by gasification.

[0067] In the process of adjusting the process parameters, the maximum removal rate of As and Sb is higher than 96%, which provides good furnace materials for subsequent pyrometallurgical gold capture.

[0068] Compared to traditional mineral processing and wet impurity removal processes, this process offers a simpler flow, easier operation, higher impurity removal rates, and avoids the large amounts of wastewater typically generated by traditional methods. During the experiment, by adjusting process parameters such as reaction temperature, As and Sb were effectively concentrated in the volatiles as sulfides and subvalent oxides, respectively, providing favorable conditions for subsequent resource recovery.

[0069] The above embodiments are examples of the implementation methods of the present invention. Although the present invention is illustrated and described using specific embodiments, it should be appreciated that the implementation methods of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for pre-treating and removing impurity elements from complex gold concentrate, characterized in that: The following steps are involved: (1) Sulfur is used as material A and complex gold concentrate is used as material B. Material A and material B are ground separately and uniformly mixed to obtain a mixed material C; (2) Place the mixed material C in a vacuum furnace, remove the air and introduce protective gas, then heat it to the preset smelting temperature and keep it warm for a certain period of time for smelting; after smelting, wait for the temperature in the furnace to drop to room temperature, and collect the residue D and volatile matter E; (3) Grinding the oxidant as material F and the residue D obtained in step (2) separately, and then uniformly mixing them to obtain a mixed material G; (4) The mixed material G is placed in a vacuum furnace and evacuated to 5Pa-50Pa; the temperature is then raised to a preset oxidation temperature and kept warm for a certain period of time for vacuum oxidation, and then the temperature is again raised to a gasification temperature and kept warm for a certain period of time for vacuum gasification; after gasification, the temperature in the furnace is lowered to room temperature, and the residue H and volatile matter I are taken out; the residue H obtained is the gold concentrate after impurities are removed; In step (1), the amount of material A added is 0.03-0.08 times the mass of material B; In step (2), during smelting, the smelting temperature is 250-450°C and the smelting time is 30-120 minutes; In step (3), the amount of material F added is 0.1-0.5 times the mass of the residue D; In step (3), the oxidant is copper oxide or lead tetroxide.

2. The method according to claim 1, wherein The impurity elements and their mass percentages in the complex gold concentrate in step (1) are: As 1%-8%, Sb 2%-10%.

3. The method according to claim 1, wherein In step (2), during smelting, the protective gas introduced is nitrogen, argon or helium; the introduction flow rate is 50-150 ml / min.

4. The method according to claim 1, wherein During the vacuum oxidation process in step (4), the oxidation temperature is 500-1000° C. and the oxidation time is 30-120 min.

5. The method according to claim 1, wherein During the vacuum vaporization process in step (4), the vaporization temperature is 700-1100° C. and the vaporization time is 30-120 min.

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