Method for comprehensive recovery of cyanide tailings

Abstract

The application belongs to the field of resource recycling and discloses a comprehensive recycling method of cyanide tailings, which comprises the following steps: mixing the cyanide tailings with pulverized coal fuel and slag type modifier, adding the mixture into a smelting furnace, introducing rich-oxygen air to smelt iron matte, and outputting gold-trapping iron matte melt, smelting slag and flue gas; transferring the gold-trapping iron matte melt into a converting furnace, adding copper-containing materials and slagging agents, introducing rich-oxygen air to convert, and outputting gold-trapping blister copper, converting slag and flue gas; adding reducing agents and sulfidizing agents to the converting slag, reducing and sulfidizing, and obtaining copper matte, depleted slag and flue gas; and sending the smelting slag and the depleted slag into an oxidation injection furnace, introducing rich-oxygen air and spraying alkaline additives through a spray gun to oxidize and inject, outputting oxidized slag for magnetic separation and enrichment, and outputting magnetite concentrate. The application is based on the characteristics of high iron and high sulfur of the cyanide tailings, directly smelts the matte by regulating the endogenous components, generates iron matte phase as a noble metal trapping medium, realizes efficient enrichment of gold and silver, effectively reduces the dependence on purchased copper concentrate, and breaks through the economic limitations of the traditional cooperative smelting process.

Description

Technical Field

[0001] This invention belongs to the field of resource recycling and processing, and in particular relates to a comprehensive recovery method for gold extraction from cyanide tailings iron matte. Background Technology

[0002] Globally, approximately 80% of gold is extracted using the cyanidation process. Due to the generally low grade of gold ore, this process generates cyanide tailings on a scale similar to the amount of raw materials processed. Cyanide tailings often contain residual cyanide, heavy metals, and recoverable valuable metals such as gold and silver. In some cases, the gold content in the tailings can reach as high as 10 g / t. Therefore, it possesses both pollution risks and resource recovery value, making it a pressing environmental and resource challenge for the gold smelting industry.

[0003] Currently, there are three main technical routes for the resource recovery and harmless disposal of gold cyanide tailings: First, the flotation enrichment-roasting method, which can recover sulfur and iron resources but cannot recover precious metals, and the harmlessness is not thorough; second, the pretreatment-cyanide leaching method, which can improve the gold and silver leaching rate but has the problems of long process, high cost and cyanide residue; third, the matte gold capture method and the high-temperature chlorination volatilization method. The former can achieve efficient gold and silver capture (recovery rate > 96%) and thorough harmlessness, but is limited by raw material impurities, while the latter can fully recover multiple metals but is difficult to scale up due to high energy consumption and equipment corrosion.

[0004] High-temperature smelting technology has proven to be an efficient and environmentally friendly hazardous waste disposal method due to its large processing capacity, thorough cyanide detoxification, and effective multi-metal recovery. Patent document CN113025821 A discloses a method of co-smelting cyanide tailings with gold and copper concentrates in an oxygen-enriched side-blown furnace. This process converts cyanide ions into harmless gases, allowing valuable metals such as gold, silver, and copper to be recovered as matte, while zinc and iron are recycled into the slag. The entire process does not generate secondary pollution. However, this technology, based on co-smelting, requires large-scale external purchase of copper concentrate as a raw material, limiting its economic efficiency due to the copper processing premium. Furthermore, it fails to fully utilize the rich iron and sulfur content in the cyanide tailings to directly create matte for gold and silver capture, resulting in low resource utilization and high overall processing costs. Therefore, there is an urgent need to develop a new matte-making process based on the regulation of the endogenous components of cyanide tailings to achieve truly low-cost and clean disposal. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above and to provide a comprehensive recovery method for cyanide tailings.

[0006] To address the aforementioned technical problems, this invention innovatively proposes a novel process for directly smelting cyanide tailings into iron matte for gold extraction, aiming to achieve the harmless disposal of cyanide hazardous waste slag from gold smelting enterprises and the comprehensive recovery of valuable metals. This technology is based on the principle of matte production for gold extraction, fully utilizing the iron, copper, and sulfur components contained in the cyanide tailings themselves to construct an iron-based matte phase dominated by FeS as a highly efficient capturing medium, achieving the directional enrichment of dispersed gold and silver in the tailings during high-temperature smelting. Unlike co-smelting processes that rely on purchased copper or lead concentrates (such as cyanide tailings-copper concentrate co-smelting for copper matte and gold extraction, cyanide tailings-lead concentrate co-smelting for precious lead and gold extraction), this invention focuses on regulating the endogenous components of the tailings, without relying on large-scale external purchases of concentrates, and has significant advantages in high resource utilization and low cost. Simultaneously, the high-temperature environment of the smelting process can completely decompose cyanide into N2 and CO2, fundamentally achieving the harmless detoxification of cyanide. The technical solution proposed in this invention is as follows:

[0007] A comprehensive recovery method for cyanide tailings includes the following steps: (1) After mixing cyanide tailings with pulverized coal fuel and slag-type conditioning agent, the mixture is added to a smelting furnace and oxygen-enriched air is introduced to smelt iron matte, producing gold-capturing iron matte melt, smelting slag and flue gas; the slag-type conditioning agent is calcium oxide and ferric oxide, and the mass ratio of the two is 2-4:4-6. (2) The gold-catching iron matte melt is transferred into a blowing furnace, and copper-containing materials and slag-forming agents are added. Oxygen-enriched air is introduced for blowing to produce gold-catching crude copper, blowing slag and flue gas. (3) Add a reducing agent and a sulfiding agent to the blown slag and carry out reduction sulfidation to obtain copper matte, lean slag and flue gas; (4) The smelting slag obtained in step (1) and the depleted slag obtained in step (3) are fed into the oxidation injection furnace. Oxygen-enriched air and alkaline additives are injected through the spray gun for oxidation injection. The oxidized slag produced after injection is magnetically separated and enriched to produce magnetite concentrate.

[0008] In the above-mentioned comprehensive recycling method for cyanide tailings, preferably, in step (1), the amount of pulverized coal fuel added is 10-30% of the mass of cyanide tailings; and the amount of slag modifier added is 5-30% of the mass of cyanide tailings.

[0009] In the above-mentioned comprehensive recovery method for cyanide tailings, preferably, in step (1), during the matte smelting process, the oxygen volume concentration of the oxygen-enriched air blown in is 60-70%, and the blowing flow rate is 10,000-20,000 Nm³ per ton of cyanide tailings under standard atmospheric pressure. 3 The melting temperature is 1200-1300℃, and the melting time is 3-5h.

[0010] Under specific atmospheric and temperature conditions during matte smelting, key components in the cyanide tailings undergo redox reactions. Some iron is oxidized and reacts with slag-forming components in the flux, such as SiO2, to form silicate-based slag; another portion of iron reacts with FeS and sulfides (MeS) of valuable metals such as copper to form iron matte. Compared to copper and nickel matte, the iron matte phase is characterized by a significantly higher iron content, typically exceeding 50%. Despite the compositional differences, iron matte shares similar physicochemical properties with copper and nickel matte, exhibiting excellent trapping capabilities for precious metals such as gold and silver. This allows for the selective enrichment of precious metal atoms in the matte phase through a dissolution-partition mechanism, and enables efficient separation of the slag and matte phases based on their different properties.

[0011] The following reactions may occur during the smelting of iron matte: 2FeS2 = 2FeS + S2 4FeS2 + 3O2 = 4FeO + SO2 2FeS + 3O2 = 2FeO + 2SO2 2Cu₂S + 3O₂ = 2Cu₂O + 2SO₂ FeS + Cu₂O = FeO + Cu₂S FeS + Cu₂S = Cu₂S·FeS FeO + O2 = Fe2O3 6FeO + O2 = 2Fe3O4 3Fe₂O₃ + FeS = 7FeO + SO₂ 2FeO + SiO2 = 2FeO·SiO2 2CaO + Fe₂O₃ = 2CaO·Fe₂O₃ In the above-mentioned comprehensive recovery method for cyanide tailings, preferably, in step (1), the main components of the gold-catching iron matte product include gold with a mass content of 50-100 g / t, silver with a mass content of 200-300 g / t, iron with a mass content of 50-70%, sulfur with a mass content of 10-30%, and copper with a mass content of 5-10%; after dust collection, the flue gas in step (1) is obtained as ash containing lead with a mass content of 3-5% and zinc with a mass content of 3-5%.

[0012] Given that gold-catching matte contains a certain amount of copper, and that iron has a significantly greater affinity for oxygen than copper, this invention employs a copper-addition method to remove iron during the blowing process. Specifically, copper-containing materials and slagging agents are added to the molten matte while oxygen-enriched air is continuously bubbled in. Under these conditions, iron is preferentially oxidized and reacts with the slagging agent components to form a slag phase; while precious metals such as gold and silver are captured by the copper phase, thus producing crude copper containing captured gold and silver. This crude copper can be sent to a copper smelting system for further enrichment and recovery of gold and silver through subsequent electrolytic refining.

[0013] In the above-mentioned comprehensive recycling method for cyanide tailings, preferably, in step (2), the copper-containing material is selected from one or more of copper matte, scrap copper, and electrolytic residue, and its addition amount is 10-30% of the mass of gold-catching iron matte; the slag-forming agent is selected from quartz, and its addition amount is 20-40% of the mass of gold-catching iron matte.

[0014] In the preferred embodiment of the above-mentioned comprehensive recovery method for cyanide tailings, in step (2), the oxygen volume concentration of the oxygen-enriched air introduced is 25-30%, and the air volume is 15000-30000 Nm³. 3 / h, blowing temperature is 1200-1250℃, blowing time is 4-6h.

[0015] In the above-mentioned comprehensive recovery method of cyanide tailings, preferably, in step (2), the grade of gold-catching crude copper is ≥98%, the copper content of the blowing slag is 5-10%, and it is transferred to the depletion furnace for sulfidation reduction smelting.

[0016] In the above-mentioned comprehensive recycling method for cyanide tailings, preferably, in step (3), the reducing agent is pulverized coal, and the amount added is 5-30% of the mass of the blown slag; the sulfiding agent is cyanide tailings, and the amount added is 10-30% of the mass of the blown slag.

[0017] In the above-mentioned comprehensive recycling method for cyanide tailings, preferably, in step (3), the temperature of the reduction sulfidation is 1250-1350℃ and the time is 1-4h.

[0018] In the above-mentioned comprehensive recycling method for cyanide tailings, preferably, in step (3), the main components of copper matte include copper with a mass content of 40-60%, iron with a mass content of 20-30%, and sulfur with a mass content of 10-20%.

[0019] In the above-mentioned comprehensive recovery method for cyanide tailings, preferably, in step (4), the alkaline additive is calcium oxide and sodium carbonate in a mass ratio of 2-4:1; the alkaline additive is mixed with oxygen-enriched air and sprayed into the molten slag through a spray gun, and the amount added is 5-15% of the mass of the molten slag. Through precise batching and control, the overall composition of the mixed material meets the requirements of FeO / SiO2 ratio of 1.8 and CaO / SiO2 ratio of 0.8, thereby providing suitable slag system conditions for the subsequent smelting process and ensuring the metal recovery rate and slag-matte separation effect.

[0020] In the preferred embodiment of the above-mentioned comprehensive recovery method for cyanide tailings, in step (4), the oxygen volume concentration in the oxygen-enriched air blown in the oxidation injection is 60-80%, and the blowing volume is 10000-20000 Nm³. 3 / h; the oxidation injection process lasts for 2-4 hours, during which pulverized coal is added to maintain the system temperature at 1200-1300℃.

[0021] In the above-mentioned comprehensive recovery method for cyanide tailings, preferably, in step (4), the grade of magnetite concentrate is 60-65%.

[0022] In the above-mentioned comprehensive recovery method for cyanide tailings, preferably, the main components of the cyanide tailings include, by mass, 5-10 g / t of gold, 20-50 g / t of silver, 30-50% of iron, 20-40% of sulfur, 3-5% of copper, 0.5-1% of lead, and 0.5-1% of zinc. The copper matte produced in step (3) is returned to the smelting process in step (2); After dust collection treatment of the flue gas generated in steps (1), (2) and (3), the flue gas is sent to produce sulfuric acid.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Based on the high iron and high sulfur characteristics of cyanide tailings, this invention directly produces matte through endogenous component regulation and smelting, generating an iron matte phase as a precious metal capture medium, achieving efficient enrichment of gold and silver, effectively reducing dependence on purchased copper concentrate, and breaking through the economic limitations of traditional co-smelting processes.

[0024] (2) In view of the material characteristics of gold-catching iron matte, which is low in copper and high in iron, the present invention adopts a copper-addition and iron-removal process. By adding copper-containing materials and oxygen-enriched blowing selectively removing iron, the matte is converted into copper, laying the foundation for further extraction and enrichment of gold and silver. On the other hand, cyanide tailings are used as sulfiding agents for the reduction smelting of blowing slag, and an internal circulation process is constructed to realize the efficient utilization of resources and waste reduction throughout the process.

[0025] (3) By integrating the short process of pyrometallurgical process of "iron matte smelting-blowing conversion-sulfidation depletion-slag magnetic separation", this invention can efficiently capture gold and silver while realizing the comprehensive recovery of associated valuable metals such as copper, lead and zinc, and simultaneously produce crude copper, magnetite concentrate and sulfuric acid and other products, which significantly improves the comprehensive resource recovery rate and overall economic benefits.

[0026] In summary, this invention addresses the resource and environmental attributes of cyanide tailings by constructing a novel iron matte smelting system centered on the endogenous components of iron, sulfur, and copper. Through process optimization and control, it achieves the synergistic recovery of multiple metals and the complete harmless treatment of cyanide in the tailings, forming a clean metallurgical technology solution with high resource recovery rate, strong adaptability, and significant hazardous waste reduction effect, while also possessing good economic and environmental benefits. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a flowchart of the comprehensive recycling process for cyanide tailings in an embodiment of the present invention. Detailed Implementation

[0029] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0030] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0031] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0032] The cyanide tailings in the following examples and comparative treatments are tailings produced after gold extraction by cyanidation of gold sulfide concentrate. They are characterized by high iron and sulfur content and polymetallic co-existence. Their main components include 42% iron, 18% sulfur, 5% copper, 0.8% lead, 1% zinc, 6 g / t gold, and 25 g / t silver by mass fraction.

[0033] Example 1: A comprehensive recovery method for cyanide tailings according to the present invention is shown in the process flow diagram below. Figure 1 As shown, it includes the following steps: (1) Using 2 tons of cyanide tailings as raw material, pulverized coal fuel and slag modifier (a mixture of calcium oxide and ferric oxide in a mass ratio of 3:5) are mixed by a batching device and a mixing belt, and transported to the feeding platform above the smelting furnace. The pulverized coal fuel is added at 10% of the mass of the cyanide tailings, and the slag modifier is added at 15% of the mass of the cyanide tailings. Oxygen-enriched air with a volume concentration of 70% is injected into the smelting furnace through a spray gun. The oxygen-enriched air flow rate is 15,000 Nm³ / h per ton of cyanide tailings at standard atmospheric pressure. The furnace is smelted at a smelting temperature of 1250℃ for 4 hours to obtain gold-catching iron matte melt, hot smelting slag, and flue gas. The main components of the gold-collecting matte, a smelting product, include 62 g / t of gold, 241 g / t of silver, 57% iron, 8% copper, and 16% sulfur by mass. The flue gas, after dust collection treatment, is sent to produce acid.

[0034] (2) The gold-catching iron matte melt in step (1) enters the smelting furnace through a chute. At the same time, scrap copper cold material and quartz slagging agent are added through the charging port at the top of the furnace. The amount of scrap copper added is 30% of the mass of iron matte, and the amount of quartz added is 25% of the mass of iron matte. After the charging is completed, oxygen-enriched air with a volume concentration of 25% is blown in at a blowing volume of 20,000 Nm³ per ton of cyanide tailings under standard atmospheric pressure. 3 / h. The process involves blowing at 1250℃ for 5 hours, producing gold-bearing crude copper, smelting slag, and flue gas. The gold-bearing crude copper has a copper grade of 98.6%. The smelting slag contains 10% copper by mass and is fed into a depletion furnace. Pulverized coal (a reducing agent) and cyaniding tailings (a sulfiding agent) are added, with the reducing agent accounting for 15% and the sulfiding agent for 20% of the slag mass. Then, reduction sulfidation smelting is carried out at 1300℃ for 3 hours. The smelting process yields copper matte, hot depletion slag, and flue gas. The main components of the copper matte include 55% copper, 21% iron, and 16% sulfur by mass. The copper matte can be returned to the oxygen-enriched blowing process. The flue gas, after dust collection treatment, is sent to produce acid.

[0035] (3) The hot smelting slag from step (1) and the hot depleted slag from step (2) are transported by ladle and added to the oxidation injection furnace. Oxygen-enriched air and alkaline composite additives (calcium oxide and sodium carbonate in a mass ratio of 3:1) are injected through a spray gun. The oxygen-enriched air has a volume concentration of 70% and a flow rate of 15,000 Nm³ / h. The composite additives are mixed with the oxygen-enriched air and injected into the oxidation injection furnace through the spray gun. Pulverized coal fuel is added during the injection process to maintain the furnace temperature at 1200℃. The entire injection process lasts for 4 hours. After the slag is quenched and granulated by air after oxidation injection, it is enriched by magnetic separation to obtain a magnetite concentrate with a grade of 61%.

[0036] According to calculations, in this embodiment, the recovery rate of gold is 98.5%, the recovery rate of silver is 99.4%, the recovery rate of copper is 96.8%, and the recovery rate of iron is 88.1%.

[0037] Example 2: A comprehensive recovery method for cyanide tailings, the process flow diagram of which is shown below. Figure 1 As shown, it includes the following steps: (1) Using 2 tons of cyanide tailings as raw material, pulverized coal fuel and slag modifier (a mixture of calcium oxide and ferric oxide in a mass ratio of 3:5) are mixed by a batching device and a mixing belt, and transported to the feeding platform above the smelting furnace. The pulverized coal fuel is added at 20% of the mass of the cyanide tailings, and the slag modifier is added at 15% of the mass of the cyanide tailings. Oxygen-enriched air with a volume concentration of 70% is injected into the smelting furnace through a spray gun. The oxygen-enriched air flow rate is 20,000 Nm³ / h per ton of cyanide tailings at standard atmospheric pressure. The furnace is smelted at a smelting temperature of 1300℃ for 3 hours to obtain gold-catching iron matte melt, hot smelting slag, and flue gas. The main components of the gold-collecting matte, a smelting product, include 75 g / t of gold, 220 g / t of silver, 63% iron, 10% copper, and 18% sulfur by mass. The flue gas, after dust collection treatment, is sent to produce acid.

[0038] (2) The gold-catching iron matte melt from step (1) enters the smelting furnace through a chute. At the same time, copper matte cold charge and quartz slagging agent are added through the charging port at the top of the furnace. The amount of copper matte cold charge added is 25% of the mass of iron matte, and the amount of quartz added is 20% of the mass of iron matte. After the charging is completed, oxygen-enriched air with a volume concentration of 30% is blown in at a blow rate of 25,000 Nm³ / h. The furnace is smelted at 1250℃ for 4 hours to produce gold-catching crude copper, smelting slag, and flue gas. The copper grade of the crude copper used for gold extraction is 98.5%, and the smelting slag contains 9.2% copper by mass. This slag is fed into a depletion furnace, where pulverized coal (a reducing agent) and cyaniding tailings (a sulfiding agent) are added. The reducing agent is added at 15% of the slag mass, and the sulfiding agent at 30%. The process is then carried out at 1300℃ for 3 hours of reduction sulfidation smelting. The smelting yields copper matte, hot depletion slag, and flue gas. The main components of the copper matte include 50% copper, 25% iron, and 12% sulfur by mass. The copper matte can be returned to the oxygen-enriched smelting process. The flue gas, after dust collection treatment, is sent to produce acid.

[0039] (3) The hot smelting slag from step (1) and the hot depleted slag from step (2) are transported by ladle and added to the oxidation injection furnace. Oxygen-enriched air and alkaline composite additives (calcium oxide and sodium carbonate in a mass ratio of 3:1) are injected through a spray gun. The oxygen-enriched air has a volume concentration of 70% and a flow rate of 15,000 Nm³ / h. The composite additives are mixed with the oxygen-enriched air and injected into the oxidation injection furnace through the spray gun. Pulverized coal fuel is added during the injection process to maintain the furnace temperature at 1200℃. The entire injection process lasts for 4 hours. After the slag is quenched and granulated by air after oxidation injection, it is enriched by magnetic separation to obtain a magnetite concentrate with a grade of 64%.

[0040] According to calculations, in this embodiment, the recovery rate of gold is 99.4%, the recovery rate of silver is 98.5%, the recovery rate of copper is 92.1%, and the recovery rate of iron is 87.9%.

[0041] Comparative Example 1: A comprehensive recovery method for cyanide tailings includes the following steps: (1) The same as step (1) in Example 1, and the main components of the smelting product gold-catching iron matte are also the same.

[0042] (2) The gold-catching iron matte melt from step (1) enters the smelting furnace through a chute. At the same time, scrap copper cold material and quartz slagging agent are added through the top charging port of the furnace. The amount of scrap copper added is 30% of the mass of iron matte, and the amount of quartz added is 20% of the mass of iron matte. After the charging is completed, oxygen-enriched air with a volume concentration of 25% is blown in at a blow rate of 20,000 Nm³ / h. The furnace is smelted at 1250℃ for 5 hours to produce gold-catching crude copper, smelting slag, and flue gas. The copper grade of the gold-catching crude copper is 98.1%, and the smelting slag contains 8.5% copper by mass. The smelting slag is sent to the depletion furnace. Pulverized coal, a reducing agent, is added to the depletion furnace at a rate of 15% of the mass of the smelting slag. Then, the furnace is reduced and smelted at 1300℃ for 3 hours. After the smelting is completed, copper matte, hot depletion slag, and flue gas are obtained. The main components of copper matte include 32% copper, 24% iron, and 11% sulfur by mass.

[0043] (3) The hot smelting slag from step (1) and the hot depleted slag from step (2) are transported via steel ladle and added to an oxidation injection furnace. Oxygen-enriched air and an alkaline composite additive (calcium oxide and sodium carbonate in a mass ratio of 3:1) are injected through a spray gun. The oxygen-enriched air has a volume concentration of 70% and a flow rate of 15,000 Nm³ / h. The composite additive is mixed with the oxygen-enriched air and injected into the oxidation injection furnace through the spray gun. Pulverized coal fuel is added during the injection process to maintain the furnace temperature at 1200℃. The entire injection process lasts for 4 hours. After the slag is quenched and granulated by air after oxidation injection, it is enriched by magnetic separation to obtain a magnetite concentrate with a grade of 63%.

[0044] According to calculations, in this embodiment, the recovery rate of gold is 98.6%, the recovery rate of silver is 99.2%, the recovery rate of copper is 65.7%, and the recovery rate of iron is 87.3%.

[0045] Comparative Example 2: A comprehensive recovery method for cyanide tailings includes the following steps: (1) The same as step (1) in Example 1, and the main components of the smelting product gold-catching iron matte are also the same.

[0046] (2) The gold-bearing iron matte obtained in step (1) is cooled, crushed, and ground. Then, the mainstream sulfuric acid leaching process is used to further separate and enrich gold, silver, and other metals. The leaching conditions are controlled as follows: liquid-to-solid ratio 2:1, temperature 65℃, pH of the slurry adjusted to about 1 by adding sulfuric acid, and leaching with conventional stirring for 4 hours. During the leaching process, sulfides in the iron matte, such as FeS, react with sulfuric acid to produce hydrogen sulfide gas, which is toxic and corrosive. A complete waste gas absorption device is required. After leaching, liquid-solid separation is carried out to obtain a leachate containing copper, iron, and other metal ions and an acid-soluble residue enriched with precious metals. The main components of the acid-soluble residue include 285 g / t of gold, 398 g / t of silver, 12% iron, 9% copper, and 8% sulfur. The acidic leachate and washing wastewater generated in this process contain residual acid, heavy metal ions, and trace amounts of cyanide. They need to be neutralized, precipitated, and otherwise treated to meet discharge standards, which is costly.

[0047] Calculations show that the recovery rates for gold, silver, and copper in this comparative example are 90.2%, 89.1%, and 34.2%, respectively.

[0048] Comparative Example 3: A comprehensive recovery method for cyanide tailings includes the following steps: (1) Using 2 tons of cyanide tailings as raw material, pulverized coal fuel and slag modifier (a mixture of calcium oxide and ferric oxide in a mass ratio of 3:1) are mixed by a batching device and a mixing belt, and transported to the feeding platform above the smelting furnace. The pulverized coal fuel is added at 9% of the mass of the cyanide tailings, and the slag modifier is added at 15% of the mass of the cyanide tailings. Oxygen-enriched air with a volume concentration of 50% is injected into the smelting furnace through a spray gun. The oxygen-enriched air flow rate is 15,000 Nm³ / h per ton of cyanide tailings at standard atmospheric pressure. The furnace is smelted at a smelting temperature of 1000℃ for 3 hours to obtain gold-catching iron matte melt, hot smelting slag, and flue gas. The main components of the gold-catching matte smelting product include 58% iron, 11% sulfur, 3% copper, 48g / t gold, and 188g / t silver by mass.

[0049] (2) The gold-catching iron matte melt from step (1) enters the smelting furnace through a chute. At the same time, copper matte cold charge and quartz slagging agent are added through the charging port at the top of the furnace. The amount of copper matte cold charge added is 20% of the mass of iron matte, and the amount of quartz added is 20% of the mass of iron matte. After the charging is completed, oxygen-enriched air with a volume concentration of 25% is blown in at a blow rate of 20,000 Nm³ / h. The furnace is smelted at 1250℃ for 4 hours to produce gold-catching crude copper, smelting slag, and flue gas. The copper grade of the crude copper used for gold extraction is 98.5%, and the smelting slag contains 9% copper by mass. This slag is fed into a depletion furnace, where pulverized coal (a reducing agent) and cyaniding tailings (a sulfiding agent) are added. The reducing agent is added at 15% of the smelting slag mass, and the sulfiding agent at 30%. The process is then carried out at 1300℃ for 3 hours of reduction sulfidation smelting. The resulting product is copper matte, hot depletion slag, and flue gas. The main components of the copper matte include 50% copper, 25% iron, and 12% sulfur by mass.

[0050] (3) The hot smelting slag from step (1) and the hot depleted slag from step (2) are transported by ladle and added to the oxidation injection furnace. Oxygen-enriched air and alkaline composite additives (calcium oxide and sodium carbonate in a mass ratio of 3:1) are injected through a spray gun. The oxygen-enriched air has a volume concentration of 70% and a flow rate of 15,000 Nm³ / h. The composite additives are mixed with the oxygen-enriched air and injected into the oxidation injection furnace through the spray gun. Pulverized coal fuel is added during the injection process to maintain the furnace temperature at 1200℃. The entire injection process lasts for 4 hours. After the slag is quenched and granulated by air after oxidation injection, it is enriched by magnetic separation to obtain a magnetite concentrate with a grade of 60%.

[0051] Calculations show that in this comparative study, the recovery rates for gold, silver, copper, and iron were 88.4%, 81.5%, 82.3.1%, and 88.2%, respectively.

Claims

1. A comprehensive recovery method for cyanide tailings, characterized in that, Includes the following steps: (1) After mixing cyanide tailings with pulverized coal fuel and slag-type conditioning agent, the mixture is added to a smelting furnace and oxygen-enriched air is introduced to smelt iron matte, producing gold-capturing iron matte melt, smelting slag and flue gas; the slag-type conditioning agent is calcium oxide and ferric oxide, and the mass ratio of the two is 2-4:4-6. (2) The gold-catching iron matte melt is transferred into a blowing furnace, and copper-containing materials and slag-forming agents are added. Oxygen-enriched air is introduced for blowing to produce gold-catching crude copper, blowing slag and flue gas. (3) Add a reducing agent and a sulfiding agent to the blown slag and carry out reduction sulfidation to obtain copper matte, lean slag and flue gas; (4) The smelting slag obtained in step (1) and the depleted slag obtained in step (3) are fed into the oxidation injection furnace. Oxygen-enriched air and alkaline additives are injected through the spray gun for oxidation injection. The oxidized slag produced after injection is magnetically separated and enriched to produce magnetite concentrate.

2. The comprehensive recovery method for cyanide tailings as described in claim 1, characterized in that, In step (1), the amount of pulverized coal fuel added is 10-30% of the mass of cyanide tailings; the amount of slag modifier added is 5-30% of the mass of cyanide tailings.

3. The comprehensive recovery method for cyanide tailings as described in claim 1, characterized in that, In step (1), during the matte smelting process, the oxygen volume concentration of the oxygen-enriched air blown in is 60-70%, and the blowing flow rate is 10,000-20,000 Nm³ per ton of cyanide tailings under standard atmospheric pressure. 3 The melting temperature is 1200-1300℃, and the melting time is 3-5h.

4. The comprehensive recovery method for cyanide tailings as described in claim 1, characterized in that, In step (2), the copper-containing material is selected from one or more of copper matte, scrap copper, and electrolytic residue, and its addition amount is 10-30% of the mass of gold-catching iron matte; the slag-forming agent is selected from quartz, and its addition amount is 20-40% of the mass of gold-catching iron matte.

5. The comprehensive recovery method for cyanide tailings as described in claim 1, characterized in that, In step (2), the oxygen volume concentration of the oxygen-enriched air is 25-30%, and the blowing volume is 10000-30000 Nm³. 3 / h, blowing temperature is 1200-1250℃, blowing time is 4-6h.

6. The comprehensive recovery method for cyanide tailings as described in claim 1, characterized in that, In step (3), the reducing agent is pulverized coal, and the amount added is 5-30% of the mass of the blown slag; the sulfiding agent is cyanide tailings, and the amount added is 10-30% of the mass of the blown slag.

7. The comprehensive recovery method for cyanide tailings as described in claim 1, characterized in that, In step (3), the temperature of the reduction vulcanization is 1250-1350℃ and the time is 1-4h.

8. The comprehensive recovery method for cyanide tailings as described in claim 1, characterized in that, In step (4), the alkaline additive is calcium oxide and sodium carbonate in a mass ratio of 2-4:1; the alkaline additive is mixed with oxygen-enriched air and sprayed into the molten slag through a spray gun, and the amount added is 5-15% of the mass of the molten slag.

9. The comprehensive recovery method for cyanide tailings as described in claim 1, characterized in that, In step (4), during oxidation blowing, the oxygen volume concentration in the injected oxygen-enriched air is 60-80%, and the blowing volume is 15000-30000 Nm³. 3 / h; the oxidation injection process lasts for 2-4 hours, during which pulverized coal is added to maintain the system temperature at 1200-1300℃.

10. The comprehensive recovery method for cyanide tailings as described in claim 1, characterized in that, The main components of the cyanide tailings include, by mass, 5-10 g / t gold, 20-50 g / t silver, 30-50% iron, 20-40% sulfur, 3-5% copper, 0.5-1% lead, and 0.5-1% zinc. The copper matte produced in step (3) is returned to the smelting process in step (2); After dust collection treatment of the flue gas generated in steps (1), (2) and (3), the flue gas is sent to produce sulfuric acid.

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