Treatment method of cyanidation tailings

Abstract

The invention relates to a treatment method of cyanidation tailings, which comprises the following steps: uniformly mixing cyanidation tailings to be treated with a slag former and a reducing agent to obtain a mixture; wherein the slag former contains one or more of CaO, SiO2 and Al2O3, so that the alkalinity of the mixture is 1.0-1.4, and the mass ratio of SiO2 to Al2O3 in the mixture is (5.0-7.0): 1; the adding amount of the reducing agent is 0.16-0.24 time of the total mass of the cyanidation tailings and the iron element in the slag former; the mixture is put into a smelting furnace and smelted for 30-120 min at the temperature of 1250-1650 DEG C, and an iron alloy melt, molten slag and flue gas are obtained; after the iron alloy melt is cooled, the iron alloy is obtained; and cooling the molten slag, and grinding to obtain the active micro powder. According to the method, the output value is remarkably improved, and the comprehensive treatment benefit of the cyanidation tailings is improved.

Description

Technical Field

[0001] The invention relates to a method for treating cyanide tailings, and belongs to the technical field of harmless treatment and resource utilization of hazardous waste. Background Art

[0002] Cyanide tailings are waste residues produced during the cyanidation gold extraction process. Because they contain cyanide and its derivatives, as well as toxic heavy metals such as lead and arsenic, they are listed on the 2021 National List of Hazardous Wastes, classified as HW33 inorganic cyanide waste. The indiscriminate dumping of cyanide tailings poses significant ecological and environmental safety risks. Cyanide tailings are also an important secondary resource, often containing valuable elements such as gold, silver, copper, iron, and lead. Recycling them would not only help increase my country's gold reserves but also contribute to the sustainable development of gold companies.

[0003] Depending on the cyanide leaching process, cyanide tailings can be divided into four categories: roasted cyanide tailings, full-sludge cyanide tailings, gold concentrate cyanide tailings, and other cyanide tailings. Roasted cyanide tailings, commonly known as red slag, account for over 50% of the total cyanide tailings. They contain low levels of valuable metals such as gold and silver, and their phase composition and distribution are complex, making them key and challenging to recycle. Currently, methods for recovering valuable metals from cyanide tailings include flotation, pretreatment-cyanidation, and pyrometallurgy. Full-sludge cyanide tailings and gold concentrate cyanide tailings contain high concentrations of gold, silver, copper, and lead, and are typically recovered using flotation or a combination of flotation and gravity separation. Roasted cyanide tailings are more commonly treated using pyrometallurgy, such as chlorination volatilization, reduction roasting-magnetic separation, and co-matte smelting. The main methods for harmless treatment of cyanide tailings include wet and pyrometallurgy. Wet methods remove cyanide by adding cyanide breakers or leaching, while pyrometallurgy removes cyanide through thermal decyanation to achieve harmlessness.

[0004] Generally speaking, high-temperature smelting is a method that can completely detoxify cyanide tailings and facilitate the recovery of valuable elements, and is more adaptable to cyanide tailings. Chinese invention patent CN100372952C discloses a method for extracting gold and silver from arsenic-containing gold concentrate tailings. The cyanide tailings are pressed into bricks and fed into a copper smelting furnace. Gold and silver are further recovered along with the copper, achieving a total recovery rate of over 97-98%. Chinese invention patent application CN106676269A discloses a method for treating cyanide tailings. The cyanide tailings, along with copper-containing materials and a reducing agent, are added to a molten bath smelting furnace. Copper is used to capture precious metals, and the iron in the cyanide tailings is converted to ferrous iron to lower the smelting temperature. The gold content in the slag can be reduced to 0.3 g / t, and the silver content to 3-5 g / t. The tailings are then converted into water-quenched slag. Chinese invention patent application CN113025821A discloses a comprehensive treatment method for resource utilization of cyanide tailings, which adds cyanide tailings and gold-copper concentrate, quartz, coal, etc. to an oxygen-enriched side-blown furnace, uses copper matte to capture gold and silver to form matte, and zinc and iron enter the slag. The above method, synergistically smelting cyanide tailings with copper-containing materials and using the formed copper matte to capture gold and silver, can achieve effective recovery of precious metals. It is a relatively ideal disposal method, but a large amount of iron in the cyanide tailings has not yet been utilized. On the other hand, the gold and silver content in the cyanide tailings is low, and a large amount of slag will be produced during the smelting process, resulting in the cost of synergistic smelting being still very high, and the slag utilization value produced is low. As can be seen from this, how to improve the value of smelting tailings has become a problem that restricts the industrial application of high-temperature smelting of cyanide tailings. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the present invention provides a method for treating cyanide tailings to effectively improve the comprehensive treatment efficiency.

[0006] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0007] A method for treating cyanide tailings comprises the following steps:

[0008] S1. Evenly mixing the cyanide tailings to be treated with a slagging agent and a reducing agent to obtain a mixture;

[0009] The slagging agent contains one or more of CaO, SiO2, and Al2O3, so that: the basicity of the mixture is 1.0-1.4, the mass ratio of SiO2 to Al2O3 in the mixture is 5.0-7.0:1; the amount of the reducing agent added is 0.16-0.24 times the total mass of the cyanide tailings and the iron element in the slagging agent;

[0010] S2. putting the mixed material into a smelting furnace and smelting at 1250-1650° C. for 30-120 min to obtain a ferroalloy melt, molten slag and flue gas;

[0011] S3, cooling the ferroalloy melt to obtain a ferroalloy;

[0012] The molten slag is cooled and then ground to obtain active fine powder.

[0013] In this way, high-temperature smelting can thermally decompose the cyanide remaining in the cyanide tailings, achieving decyanation and detoxification. Simultaneously, through a single-step smelting process, the large amount of iron in the cyanide tailings is reduced to molten iron, which is then used to capture high-boiling-point valuable metals such as gold and copper, resulting in a ferroalloy melt. After being reduced, low-boiling-point elements such as silver, lead, and arsenic evaporate into the flue gas, which can be quenched and filtered through heat exchange to produce flue dust enriched in elements such as silver, lead, and arsenic. By adding a slag-forming agent, a high-alkalinity CaO-SiO2-Al2O3 ternary slag is prepared for reduction smelting, destroying the original structure of the cyanide tailings and releasing valuable elements such as gold, silver, copper, and lead, enabling more complete metal recovery. By regulating the basicity and SiO2 / Al2O3 ratio of the incoming feed, high-grade and high-recovery gold- and copper-bearing pig iron alloys are produced. Furthermore, the amount of calcium silicate and calcium aluminosilicate, which are active in gelling, produced in the molten slag is increased, thereby enhancing the activity of the slag. The molten slag is rapidly cooled to form a glassy substance, which, after being ground, exhibits high activity and meets the requirements of "Granulated Blast Furnace Slag for Cement, Mortar, and Concrete" (GB / T 18046-2017). It can be used as a cement admixture, effectively improving the efficiency of cyanide tailings treatment.

[0014] The present invention adopts a high-temperature smelting method to treat cyanide tailings, and obtains ferroalloy by one-step smelting. The obtained molten slag can be directly made into active materials, which can effectively improve the resource utilization value of the cyanide tailings.

[0015] The applicant has found that by controlling the alkalinity at 1.0-1.4, a large amount of iron in the cyanide tailings can be reduced to elemental iron, forming molten iron that captures high-boiling point elements such as gold and copper, forming an iron alloy that sinks to the bottom and is better separated from the molten slag.

[0016] In the present invention, basicity refers to ternary basicity, that is, R = (CaO) / (SiO2 + Al2O3), specifically: the ratio of the mass of CaO to the total mass of SiO2 and Al2O3.

[0017] Furthermore, the alkalinity of the mixture is 1.1-1.3, and further 1.15-1.25.

[0018] Furthermore, the mass ratio of SiO2 to Al2O3 in the mixture is 6.0-6.8:1, and further 6.2-6.6:1.

[0019] Furthermore, the amount of the reducing agent added is 0.18-0.22 times, and further 0.19-0.21 times, of the total mass of the cyanide tailings and the iron element in the slagging agent.

[0020] Furthermore, the reducing agent is one or more of coke, coal, and waste activated carbon.

[0021] Furthermore, in S1, the cyanide tailings to be treated are evenly mixed with a slagging agent and a reducing agent, and pelletized to obtain a mixture.

[0022] Furthermore, in S2, the mixed material is put into an induction melting furnace and smelted at 1250-1500° C. for 30-90 minutes. The molten iron produced during the smelting process can be used as a heat medium by heating in the induction melting furnace, which helps to reduce the smelting temperature and increase the smelting speed.

[0023] Furthermore, in S3, the molten slag is cooled and then coarsely ground to 60-150 mesh, and then subjected to dry magnetic separation to obtain magnetic powder and non-magnetic powder; the non-magnetic powder is then finely ground to obtain active micropowder;

[0024] The magnetic powder is combined with a ferroalloy to obtain a ferroalloy product.

[0025] Furthermore, the ferroalloy is ground and then combined with the magnetic powder to obtain a powdered ferroalloy product. Optionally, the ferroalloy is ground to a size of 40-200 mesh.

[0026] Furthermore, in S2, the cooled molten slag is ground by dry grinding. Optionally, the fineness of the active micropowder is 350-550 μm, calculated based on the specific surface area. 2 / kg.

[0027] Optionally, during fine grinding, 0.1-0.5 wt% of the total amount of the non-magnetic powder is added as a grinding aid. Optionally, the grinding aid comprises one or more of triethanolamine, sodium acetate, ethylene glycol, and propylene glycol.

[0028] Furthermore, in the cyanide tailings, the content of SiO2 is 30-50wt%, the content of Fe2O3 is 35-55wt%, the content of Al2O3 is 1-10wt%, the content of CaO is 0.1-5wt%, the content of MgO is 0-2wt%, the content of Cu is 0-3wt%, the content of Pb is 0-5wt%, the content of Au is 0.1-15g / t, the content of Ag is 1-200g / t, and the content of cyanide is 10-35mg / kg.

[0029] Furthermore, the moisture content of the cyanide tailings is ≤5wt%.

[0030] Furthermore, the moisture content of the slagging agent is ≤5wt%.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The present invention achieves harmlessness and resource utilization of cyanide tailings through one-step smelting, which not only recovers a large amount of iron, but also the obtained molten slag has high gelling activity and can be used as active micropowder after grinding, which can significantly increase the output value and effectively improve the comprehensive treatment efficiency of cyanide tailings.

[0033] 2. The present invention adopts a direct ironmaking process to dispose of cyanide tailings, avoiding the problem of iron not being able to be utilized or requiring secondary ironmaking in the co-smelting process. The molten slag is converted into active micropowder that can be used for cementitious materials, and basically no solid waste is generated, which can more significantly dispose of the cyanide tailings.

[0034] 3. The present invention adopts a high-alkalinity CaO-SiO2-Al2O3 ternary slag for reduction smelting. The ground molten slag can reach the activity of S105 level. Compared with conventional blast furnace slag, MgO and Al2O3 are lower, which is beneficial to improving the performance of the molten slag and is a high-quality cement active material.

[0035] 4. The present invention adopts an induction melting furnace for melting, which effectively lowers the melting temperature and reduces energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The present invention discloses an XRD pattern of cyanide tailings. DETAILED DESCRIPTION

[0037] The present invention will be described in detail below with reference to the embodiments. It should be noted that, unless otherwise specified, the embodiments and features of the embodiments of the present invention may be combined with each other. Unless otherwise specified, the relevant percentages are percentages by mass.

[0038] The composition of the cyanide tailings used in the embodiments and comparative examples of the present invention is shown in Table 1, and the XRD patterns are shown in Table 1. Figure 1 shown.

[0039] Table 1

[0040] Element <![CDATA[SiO2]]> <![CDATA[Fe2O3]]> <![CDATA[Al2O3]]> CaO MgO Cu Pb <![CDATA[Au a ]]> <![CDATA[Ag a ]]> <![CDATA[Cyanide b > content / % 41.95 46.74 6.42 1.63 0.43 0.24 1.10 1.06 46.66 18.40

[0041] In the table, a. indicates the unit is g / t; b. indicates the unit is mg / kg.

[0042] Example 1

[0043] The processing method of the cyanide tailings of the present embodiment is as follows:

[0044] 64 parts by weight of cyanide tailings, 36 parts of a slagging agent, and 4.0 parts of a reducing agent were uniformly mixed and pelletized. The pellets were then placed in an induction smelting furnace. The slagging agent was calcium oxide, and the total amount of iron in the cyanide tailings and the slagging agent was 19.78 wt%. The reducing agent was coke powder, used in an amount equal to 0.20 times the total amount of iron. After the raw materials were placed in the furnace, they were kept at 1400°C for 60 minutes, undergoing reduction smelting to produce a ferroalloy melt and molten slag. The flue gas generated during the smelting process was quenched and collected to produce dust.

[0045] After smelting, the mixture is cooled naturally, and then the crucible is taken out to obtain the pig iron alloy and slag. The pig iron alloy is ground to 100 mesh in a closed environment to obtain active pig iron powder; the slag is ground to 100 mesh and then fed into a dry magnetic separator for magnetic separation to obtain magnetic and non-magnetic materials; the obtained magnetic materials are mixed with the active pig iron powder to form the final active pig iron powder; the obtained non-magnetic materials are mixed with 0.1wt% triethanolamine (grinding aid) by weight of the non-magnetic materials and then continue to be dry ground until the specific surface area reaches 500±10m 2 / kg, and active micropowder is obtained.

[0046] Example 2

[0047] Example 1 was repeated, except that 67 parts of cyanide tailings, 33 parts of slagging agent, and 4.1 parts of reducing agent were uniformly mixed, first formed into pellets, and then charged into an induction smelting furnace, wherein the slagging agent was calcium oxide, and the total amount of iron in the cyanide tailings and the slagging agent was 20.71 wt%; and the reducing agent was coke powder, and the amount used was 0.20 times the total amount of iron.

[0048] Example 3

[0049] Example 1 was repeated, except that 61 parts of cyanide tailings, 39 parts of slagging agent, and 3.8 parts of reducing agent were uniformly mixed, first formed into pellets, and then charged into an induction smelting furnace, wherein the slagging agent was calcium oxide, and the total amount of iron in the cyanide tailings and the slagging agent was 18.86 wt %; and the reducing agent was coke powder, and the amount used was 0.20 times the total amount of iron.

[0050] Example 4

[0051] Example 1 was repeated, except that 62.8 parts of cyanide tailings, 37.2 parts of a slagging agent, and 3.9 parts of a reducing agent were uniformly mixed, first formed into pellets, and then charged into an induction melting furnace. The slagging agent included 36.4 parts of calcium oxide and 0.8 parts of aluminum oxide, and the total amount of iron in the cyanide tailings and the slagging agent was 19.41 wt %. The reducing agent was coke powder, and the amount used was 0.20 times the total amount of iron.

[0052] Example 5

[0053] Example 1 was repeated, except that 63.4 parts of cyanide tailings, 36.6 parts of a slagging agent, and 3.9 parts of a reducing agent were uniformly mixed, first formed into pellets, and then charged into an induction smelting furnace, wherein the slagging agent consisted of 36.2 parts of calcium oxide and 0.4 parts of aluminum oxide, and the total amount of iron in the cyanide tailings and the slagging agent was 19.60 wt %. The reducing agent was coke powder, and the amount used was 0.20 times the total amount of iron.

[0054] Comparative Example 1

[0055] Example 1 was repeated, except that 71.8 parts of cyanide tailings, 28.2 parts of a slagging agent, and 4.4 parts of a reducing agent were uniformly mixed, first formed into pellets, and then charged into an induction smelting furnace, wherein the slagging agent was calcium oxide, and the total amount of iron in the cyanide tailings and the slagging agent was 22.19 wt %; and the reducing agent was coke powder, and the amount used was 0.20 times the total amount of iron.

[0056] Comparative Example 2

[0057] Example 1 was repeated, except that 57.7 parts of cyanide tailings, 42.3 parts of a slagging agent, and 3.7 parts of a reducing agent were uniformly mixed, first formed into pellets, and then charged into an induction smelting furnace, wherein the slagging agent was calcium oxide, and the total amount of iron in the cyanide tailings and the slagging agent was 17.84 wt %; and the reducing agent was coke powder, and the amount used was 0.20 times the total amount of iron.

[0058] Comparative Example 3

[0059] Example 1 was repeated, except that 61.4 parts of cyanide tailings, 38.6 parts of a slagging agent, and 3.8 parts of a reducing agent were uniformly mixed, first formed into pellets, and then charged into an induction melting furnace, wherein the slagging agent consisted of 36.8 parts of calcium oxide and 1.8 parts of aluminum oxide, and the total amount of iron in the cyanide tailings and the slagging agent was 18.98 wt %. The reducing agent was coke powder, and the amount used was 0.20 times the total amount of iron.

[0060] Comparative Example 4

[0061] Example 1 was repeated, except that 58.6 parts of cyanide tailings, 41.4 parts of a slagging agent, and 3.6 parts of a reducing agent were uniformly mixed, first formed into pellets, and then charged into an induction smelting furnace, wherein the slagging agent consisted of 37.6 parts of calcium oxide and 3.8 parts of quartz sand, and the total amount of iron in the cyanide tailings and the slagging agent was 18.11 wt %; and the reducing agent was coke powder, and the amount used was 0.20 times the total amount of iron.

[0062] Comparative Example 5

[0063] Repeat Example 1, except that the magnetic separation step is omitted, the slag is ground to 100 mesh, 0.1 wt% ethylene glycol is added to the total amount of slag, and dry grinding is continued until the specific surface area reaches 500 ± 10 m 2 / kg, and active micropowder is obtained.

[0064] Comparative Example 6

[0065] Example 1 was repeated, except that 64 parts of cyanide tailings, 36 parts of slagging agent, and 2.0 parts of reducing agent were uniformly mixed, first formed into pellets, and then charged into an induction melting furnace, wherein the slagging agent was calcium oxide, and the total amount of iron in the cyanide tailings and the slagging agent was 19.78 wt %; and the reducing agent was coke powder, and the amount used was 0.10 times the total amount of iron.

[0066] The composition of the mixture of cyanide tailings and slagging agent in the various embodiments and comparative examples of the present invention is shown in Table 2. The grades and recoveries of Pb and Ag in the dust collected from the reduction smelting are shown in Table 3. The grades and recoveries of Fe, Cu, and Au in the resulting activated pig iron powder are shown in Table 3. The composition and activity index of the resulting activated micropowder are shown in Table 4.

[0067] The specific surface area is tested according to the standard “Determination of specific surface area of ​​cement - Blaine method” (GB / T 8074-2008).

[0068] Among them, the activity index is tested according to the standard "ISO method for test method of cement mortar strength" (GB / T 17671-2021), and the cement used in the test is the benchmark cement P.I42.5.

[0069] Table 2

[0070]

[0071]

[0072] Table 3

[0073]

[0074] a. The unit of grade is g / t.

[0075] Table 4

[0076]

[0077]

[0078] Note: In the table, TiO2+MnO represents the total content of TiO2 and MnO; mass coefficient K = (CaO+MgO+Al2O3) / (SiO2+TiO2+MnO).

[0079] Tables 3 and 4 show that cyanide tailings, mixed with a slagging agent and a reducing agent, can be reduced and smelted at high temperatures to recover iron, gold, copper, lead, and silver in a single step. The ground slag exhibits high activity, with the 28-day activity index meeting the requirements of GB / T17671-2021. Increasing alkalinity increases the iron and copper grades and decreases the recovery rate, while the opposite is true for silver, resulting in an increased activity index for the resulting active micropowder. Increasing the SiO2 / Al2O3 ratio decreases the iron and copper grades and increases the recovery rate, while the opposite is true for silver, with the activity index of the resulting active micropowder decreasing with alkalinity. Lead and gold are less affected by alkalinity and the SiO2 / Al2O3 ratio. Overall, controlling the basicity to 1.0-1.4 and the SiO2 / Al2O3 ratio to 5-7 results in higher metal grade, higher recovery rate, and higher activity index of the active micropowder. Higher basicity and SiO2 / Al2O3 ratios require the addition of more slagging agents, which reduces the relative content of cyanide tailings in the mixture, lowering treatment efficiency and potentially outweighing the benefits. Coarsely grinding the slag and then subjecting it to magnetic separation effectively recovers some of the metallographic structures dispersed within the slag, improving metal recovery. While the recovery of some iron silicate through magnetic separation may reduce iron grade, this does not affect the use of the active pig iron powder.

[0080] The contents illustrated in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent modifications of the present invention by those skilled in the art shall fall within the scope defined by the claims attached to this application.

Claims

1. A method for treating cyanide tailings, characterized in that: The steps include: S1. Evenly mixing the cyanide tailings to be treated with a slagging agent and a reducing agent to obtain a mixture; The slagging agent contains one or more of CaO, SiO2, and Al2O3, so that: the basicity of the mixture is 1.0-1.4, the mass ratio of SiO2 to Al2O3 in the mixture is 5.0-7.0:1; the amount of the reducing agent added is 0.16-0.24 times the total mass of the cyanide tailings and the iron element in the slagging agent; S2. putting the mixed material into a smelting furnace and smelting at 1250-1650° C. for 30-120 min to obtain a ferroalloy melt, molten slag and flue gas; S3, cooling the ferroalloy melt to obtain a ferroalloy; The molten slag is cooled and then ground to obtain active fine powder.

2. The processing method according to claim 1, characterized in that The alkalinity of the mixture is 1.1-1.

3.

3. The processing method according to claim 1, characterized in that The mass ratio of SiO2 to Al2O3 in the mixture is 6.0-6.8:

1.

4. The processing method according to claim 1, characterized in that The amount of reducing agent added is 0.18-0.22 times the total mass of the iron element in the cyanide tailings and the slagging agent.

5. The processing method according to claim 1, characterized in that The reducing agent is one or more of coke, coal, and waste activated carbon.

6. The processing method according to claim 1, characterized in that In S1, the cyanide tailings to be treated are evenly mixed with a slagging agent and a reducing agent, and pelletized to obtain a mixture.

7. The processing method according to claim 1, characterized in that In S2, the mixed material is put into an induction melting furnace and smelted at 1250-1500°C for 30-90 minutes.

8. The processing method according to any one of claims 1 to 7, characterized in that: In S3, the molten slag is cooled and then coarsely ground to 60-150 mesh, and then subjected to dry magnetic separation to obtain magnetic powder and non-magnetic powder; the non-magnetic powder is then finely ground to obtain active micropowder; The magnetic powder is combined with a ferroalloy to obtain a ferroalloy product.

9. The processing method according to claim 8, characterized in that: The ferroalloy is ground and then combined with the magnetic powder to obtain a powdered ferroalloy product.

10. The processing method according to any one of claims 1 to 7, characterized in that: The cyanide tailings have a SiO2 content of 30-50wt%, a Fe2O3 content of 35-55wt%, an Al2O3 content of 1-10wt%, a CaO content of 0.1-5wt%, a MgO content of 0-2wt%, a Cu content of 0-3wt%, a Pb content of 0-5wt%, an Au content of 0.1-15g / t, an Ag content of 1-200g / t, and a cyanide content of 10-35mg / kg.

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