Method and system for graded recovery of valuable components by fluidization and pre-reduction of cyanide tailings

Abstract

This invention belongs to the fields of mining and metallurgical engineering, specifically a method and system for the graded recovery of valuable components from cyanide tailings through fluidized bed regenerative pre-reduction. The method includes: S1, drying and preheating the cyanide tailings, followed by fluidized bed roasting to remove cyanide and impurities, yielding decyanated tailings; S2, utilizing the heat carried by the decyanated tailings obtained in S1 for fluidized bed regenerative pre-reduction, yielding gold-rich sponge iron and metal-rich flue gas; S3, heating and reducing the gold-rich sponge iron obtained in S2, yielding reduced gold-rich sponge iron and metal-rich flue gas; S4, hot-pressing the reduced gold-rich sponge iron obtained in S3 into hot-pressed blocks, and then arc-melting the hot-pressed blocks to separate pure iron and gold-rich iron; S5, cooling and melting the gold-rich iron obtained in S4 to separate gold and iron; S6, graded and directly condensing the metal-rich flue gas obtained in S2 and S3. This invention achieves efficient recovery of all valuable components (gold, silver, iron, zinc, and lead) from cyanide tailings.

Description

Technical Field

[0001] This invention belongs to the fields of mining and metallurgical engineering, and specifically relates to a method and system for graded recovery of valuable components from fluidized bed thermal regenerative pre-reduction of cyanide tailings. Background Technology

[0002] Cyanide tailings are a major solid waste generated by the gold smelting industry. According to domestic statistics, its annual discharge reaches approximately 20 million tons, with a huge historical stockpile. This type of tailings has a complex composition, containing not only residual cyanide but also a variety of valuable elements. Iron is the most abundant valuable element in cyanide tailings, generally ranging from 20% to 40%. Gold, silver, lead, and zinc are also common valuable metals in cyanide tailings, usually in lower concentrations: gold 0.5g / t to 1.5g / t, silver 8g / t to 40g / t, lead 1.5g / t to 4%, and zinc 0.7g / t to 3%, making them of significant recovery value.

[0003] Currently, there are three main types of resource recovery technologies for cyanide tailings. First, wet extraction technologies, such as ozone oxidation or slurry electrolysis, recover or remove valuable metals while eliminating the toxicity of cyanide. While these methods offer good metal recovery selectivity, they generally suffer from high reagent consumption, long process flows, and difficulties in wastewater treatment. Second, pyrometallurgical reduction smelting technologies convert iron oxides in tailings into metallic iron through high-temperature reduction reactions, enabling direct iron production and enrichment of other valuable metals. However, this technology is energy-intensive, and the dense structure of phases such as fritillary olivine in the slag leads to poor reduction efficiency and slag-iron separation. Third, mineral processing and enrichment technologies separate and enrich pyrite concentrates (e.g., FeS2 can be purified from 40%–50% to over 90%) or residual copper, lead, and other valuable minerals through physical methods such as flotation. However, traditional mineral processing methods have limited efficiency in separating finely dispersed or cyanide-complexed valuable metals and cannot solve the cyanide pollution problem in the final tailings.

[0004] Patent CN202410280672.6 discloses a treatment process for cyanide tailings, which recovers valuable metals through grinding, flotation, and roasting. While this method achieves a certain degree of metal recovery, the roasting process is energy-intensive and lacks an effective waste heat recovery system, resulting in low thermal efficiency. The flotation process requires the addition of various chemical reagents, increasing processing costs and potentially introducing new environmental risks. Furthermore, the overall resource utilization efficiency needs improvement. Patent CN201410455720.7 discloses a decyanation process for cyanide tailings. This system connects a pretreatment reaction unit, a thickener, and a flotation unit sequentially. It uses primary decyanation reagents such as FeSO4·7H2O, CuSO4·5H2O, and cobalt chloride, and secondary decyanation reagents such as polyferric sulfate and polyaluminum chloride to improve the gold recovery rate in the flotation concentrate. However, this method has high reagent costs, potential secondary pollution risks, and a long pretreatment and flotation process. Summary of the Invention

[0005] This invention addresses the problems existing in current cyanide tailings treatment technologies by providing a fluidized bed thermal regenerative pre-reduction method and system for the graded recovery of valuable components from cyanide tailings. This system can treat cyanide tailings with gold content of 0.2 g / t to 2 g / t, silver content of 5 g / t to 50 g / t, iron content of 20% to 50%, lead content of 1% to 5%, and zinc content of 0.3% to 7%.

[0006] In a first aspect, the present invention provides a method for the graded recovery of valuable components from fluidized bed thermal regenerative pre-reduction of cyanide tailings, comprising the following steps: S1. After drying and preheating, the cyanide tailings are subjected to fluidized bed roasting to remove cyanide and impurities, resulting in cyanide-removed tailings. S2. Utilize the heat carried by the cyanide removal tailings obtained in S1 for fluidized bed regenerative pre-reduction to obtain gold-rich sponge iron and metal-rich flue gas. S3. The gold-rich sponge iron obtained in S2 is heated and reduced to obtain heated and reduced gold-rich sponge iron and metal-rich flue gas. S4. The gold-rich sponge iron obtained from S3 after heating and reduction is hot-pressed into a hot-pressed block, and the hot-pressed block is then subjected to electric arc melting to separate pure iron and gold-rich iron. S5. The gold-rich molten iron obtained in S4 is subjected to cooling and melting treatment to separate the gold from the iron. S6. The metal-rich flue gas obtained from S2 and S3 is directly condensed in stages.

[0007] Furthermore, the particle size of the dried and preheated cyanide tailings in step S1 is <1 mm; for example, it can be 0.1 mm, 0.3 mm, 0.5 mm, 0.7 mm, 0.9 mm, etc.

[0008] Furthermore, the drying preheating temperature is 150℃~200℃; for example, it can be 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, etc.

[0009] Furthermore, the drying preheating time is 10s to 20s; for example, it can be 10s, 11s, 12s, 13s, 14s, 15s, 16s, 17s, 18s, 19s, 20s, etc.

[0010] Furthermore, the moisture content of the cyanide tailings after drying and preheating is ≤1%.

[0011] This invention utilizes the high-temperature flue gas returned from the fluidized bed roasting decyanation and impurity removal process to preheat and dry the cyanide tailings, ensuring that the moisture content of the dried and preheated cyanide tailings is ≤1%, thus guaranteeing the full cyanide removal reaction of the material during the subsequent fluidized bed roasting process.

[0012] Furthermore, the fluidized roasting decyanation and impurity removal process described in step S1 is carried out during the exothermic combustion of the roasting gas.

[0013] Furthermore, the roasting gas includes air and coal gas, and the volume concentration of the coal gas is 20% to 40%; for example, it can be 20%, 25%, 30%, 35%, 40%, etc. The volume concentration of coal gas is the percentage of coal gas in the total volume of the (coal gas + air) mixture. Unless otherwise specified in this invention, the coal gas mentioned is converter gas, which has the highest carbon monoxide content, approximately 45% to 70%, and a lower hydrogen content, typically less than 2%.

[0014] Furthermore, the calcination temperature for fluidized bed roasting to remove cyanide and impurities is 1100℃~1200℃; for example, it can be 1100℃, 1110℃, 1120℃, 1130℃, 1140℃, 1150℃, 1160℃, 1170℃, 1180℃, 1190℃, 1200℃, etc.

[0015] Furthermore, the calcination time for fluidized bed roasting to remove cyanide and impurities is 10s to 20s; for example, it can be 10s, 12s, 14s, 16s, 18s, 20s, etc.

[0016] Furthermore, the impurities removed in step S1 include cyanide, water of crystallization, and hydroxyl groups.

[0017] This invention involves drying and preheating cyanide tailings, then heating and decomposing them in a suspended state, followed by fluidized bed roasting to remove cyanide and impurities such as cyanide ions, water of crystallization, and hydroxyl groups, generating a relatively simple metal oxide, thus obtaining cyanide-removed tailings.

[0018] Furthermore, the fluidized thermal storage pre-reduction described in step S2 is carried out in preheated reducing gas, which is the gas returned from the heating and reduction process in step S3.

[0019] Furthermore, the preheating reducing gas includes nitrogen and coal gas, and the coal gas flow rate is based on a ratio of the total volume of reducing gases in the coal gas to the mass of cyanide tailings powder of approximately 0.4 m³. 3 / kg~1.2m 3 / kg; for example, it could be 0.4m 3 / kg, 0.5m 3 / kg, 0.6m 3 / kg, 0.7m 3 / kg, 0.8m 3 / kg, 0.9m 3 / kg, 1.0m 3 / kg, 1.1m 3 / kg, 1.2m 3 / kg, etc. The gas in the preheating reducing gas is converter gas; nitrogen, as a carrier gas, does not participate in the reduction reaction, and its introduction rate can be routinely determined according to the requirements of fluidized bed operation.

[0020] Furthermore, the temperature of the fluidized thermal storage pre-reduction is 800℃~950℃; for example, it can be 800℃, 820℃, 840℃, 860℃, 880℃, 900℃, 920℃, 940℃, 950℃, etc.

[0021] Furthermore, the fluidized heat storage pre-reduction time is 20 min to 60 min; for example, it can be 20 min, 30 min, 40 min, 50 min, 60 min, etc.

[0022] Furthermore, the metal-rich flue gas contains lead and silver, which are reduced to elemental metals and volatilized into the gas phase during the fluidized regenerative pre-reduction process. The resulting gold-rich sponge iron has an iron metallization rate of 65% to 95%.

[0023] Furthermore, the heating and reduction described in step S3 is carried out in a mixed atmosphere of preheated reducing gas and roasting gas. The preheated reducing gas is the gas returned from the hot pressing process in step S4, and the roasting gas is the exothermic reflux gas from the fluidized roasting decyanation and impurity removal process in step S1. The purpose is to utilize the roasting gas (including air) for combustion heating and to regulate the furnace temperature and atmosphere while reducing iron oxides. The amount of each gas introduced can be adjusted conventionally according to the degree of reduction and heat balance requirements.

[0024] Furthermore, the preheating reducing gas includes nitrogen and coal gas, and the roasting gas includes air and coal gas.

[0025] Furthermore, the heating and reduction temperature is 950–1200°C; for example, it can be 950°C, 970°C, 990°C, 1000°C, 1050°C, 1100°C, 1150°C, 1200°C, etc.

[0026] Furthermore, the heating and reduction time is 20 min to 60 min; for example, it can be 20 min, 30 min, 40 min, 50 min, 60 min, etc.

[0027] Furthermore, the metal-rich flue gas after heating and reduction contains zinc. During the heating and reduction process, the zinc is reduced to a metallic element and volatilizes into the gas phase, and returns to the fluidized heat storage pre-reduction process in step S2 along with the preheated reducing gas. The iron metallization rate in the resulting metal-rich sponge iron after heating and reduction is 65% to 95%.

[0028] Furthermore, the hot pressing process described in step S4 is carried out in a preheated reducing gas, which is the gas returned from the electric arc melting process in step S4. The preheated reducing gas serves only as a protective atmosphere in the hot pressing process to prevent the gold-rich sponge iron from oxidizing at high temperatures and does not participate in the chemical reaction. The gas flow rate can be adjusted according to the hot pressing equipment and production requirements to ensure positive pressure and an inert environment inside the furnace.

[0029] Furthermore, the hot pressing temperature is 600℃~800℃; for example, it can be 600℃, 620℃, 650℃, 680℃, 700℃, 720℃, 750℃, 780℃, 800℃, etc.

[0030] Furthermore, the pressure of the hot pressing is 200MPa to 400MPa; for example, it can be 200MPa, 220MPa, 250MPa, 270MPa, 300MPa, 320MPa, 350MPa, 370MPa, 400MPa, etc.

[0031] Furthermore, the hot pressing time is 5 min to 15 min; for example, it can be 5 min, 7 min, 10 min, 12 min, 15 min, etc.

[0032] Furthermore, the iron metallization rate in the hot-pressed block is not less than 65%.

[0033] Furthermore, the density of the hot-pressed block is 4.5–5.5 g / cm³. 3 For example, it could be 4.5 g / cm³. 3 4.7 g / cm 3 4.9 g / cm 3 5.0 g / cm 3 5.5 g / cm 36.0 g / cm 3 wait.

[0034] Furthermore, the arc melting described in step S4 is carried out in preheated reducing gas, which is the gas returned from the cooling melting process in step S5. The amount of coal gas introduced into the preheated reducing gas is limited according to the mass ratio of reducing gas to ore powder (the amount of coal gas introduced is based on the mass ratio of the total volume of reducing gas in the coal gas to the mass of cyanide tailings ore powder being within 0.4 m³). 3 / kg~1.2m 3 / kg), nitrogen is used as a carrier gas and does not participate in the reaction; the role of the preheating reducing gas in the electric arc melting process is the same as that of the fluidized regenerative pre-reduction described in step S2, and the flow rate of each gas can be adjusted according to the melting temperature and furnace pressure.

[0035] Furthermore, the temperature of the electric arc melting is 1350℃~1600℃; for example, it can be 1350℃, 1400℃, 1450℃, 1500℃, 1550℃, 1600℃, etc.

[0036] Furthermore, the arc melting time is 30 min to 50 min; for example, it can be 30 min, 35 min, 40 min, 45 min, 50 min, etc.

[0037] Furthermore, the iron content in the pure iron molten iron is not less than 98 wt%.

[0038] Furthermore, the enrichment factor of gold in the gold-rich molten iron is not less than 10 times.

[0039] Furthermore, the cooling and melting process described in step S5 is carried out in a reducing gas; after absorbing the heat from the gold-rich molten iron, the reducing gas is converted into preheated reducing gas and returned to the arc melting process in step S4.

[0040] Furthermore, the reducing gas includes nitrogen and coal gas.

[0041] Furthermore, the cooling and melting process lowers the temperature of the gold-rich molten iron to 900℃~1100℃, for example, 900℃, 920℃, 950℃, 970℃, 1000℃, 1050℃, 1100℃, etc. Within this temperature range, iron is transformed into a solid iron framework, while gold remains in the liquid phase, achieving the separation of gold and iron through solid-liquid separation.

[0042] Furthermore, in step S6, the staged direct condensation in the condensing gas (including nitrogen) is sequentially condensed and separated according to the differences in dew point temperatures of silver, zinc, and lead. The separated metal-rich flue gas is converted into demetallized flue gas and returned to the fluidized bed roasting decyanation and impurity removal process in step S1. The demetallized flue gas after staged condensation has extremely low oxygen content and needs to undergo dust removal treatment before returning to the fluidized bed roasting decyanation and impurity removal process in step S1. Returning to the fluidized bed roasting decyanation and impurity removal process only serves as a heat source and auxiliary reducing gas supplement, which is beneficial for the recovery and utilization of system tail gas and will not have a negative impact on the decyanation and impurity removal process.

[0043] Furthermore, the silver is condensed and precipitated in the high-temperature condensation section at 900℃~1000℃; for example, it can be 900℃, 920℃, 940℃, 960℃, 980℃, 1000℃, etc.

[0044] Furthermore, the zinc is condensed and precipitated in the medium-temperature condensation section at 550℃ to 750℃; for example, it can be 550℃, 570℃, 590℃, 610℃, 630℃, 650℃, 670℃, 690℃, 710℃, 730℃, 750℃, etc.

[0045] Furthermore, the lead is condensed and precipitated in the low-temperature condensation section at 350℃~420℃; for example, it can be 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, 410℃, 420℃, etc.

[0046] Furthermore, it also includes S7, exhaust gas treatment: the high-temperature flue gas from the drying and preheating of the cyanide tailings in step S1 is used as exhaust gas for purification treatment. The solid dust obtained after purification is subjected to fluidized bed roasting for cyanide removal and impurity removal, and the purified gas is discharged from the system. The high-temperature flue gas after drying and preheating is purified by dust removal, and the solid dust is returned to the fluidized bed roasting for cyanide removal and impurity removal process to participate in the reaction again. The gas is then purified before being discharged, which not only recovers the valuable components entrained in the flue gas, but also achieves the goal of exhaust gas meeting emission standards.

[0047] Secondly, the present invention also provides a fluidized bed thermal regenerative pre-reduction system for the graded recovery of valuable components from cyanide tailings, comprising: A drying and preheating device is used to dry and preheat cyanide tailings; A fluidized bed roasting apparatus, connected to the drying and preheating apparatus, is used to perform fluidized bed roasting to remove cyanide and impurities from the preheated cyanide tailings. A fluidized bed regenerative pre-reduction device is connected to the fluidized bed roasting device. It uses the sensible heat of the roasting outlet material to perform fluidized bed regenerative pre-reduction on the cyanide removal tailings, and outputs gold-rich sponge iron and metal-rich flue gas respectively. The heating and reduction device is connected to the fluidized heat storage pre-reduction device to heat and reduce the gold-rich sponge iron, and outputs the heated and reduced gold-rich sponge iron and the metal-rich flue gas respectively. A hot pressing forming device is connected to the heating and reduction device to hot press gold-rich sponge iron into hot pressing blocks. An electric arc furnace melting device is connected to the hot pressing forming device to melt the hot pressing block and separate and output pure iron and gold-rich iron. A cooling and melting device is connected to the electric arc furnace smelting device to cool and melt gold-rich molten iron, thereby separating gold from iron. A staged condensation device is connected to the fluidized bed heat storage pre-reduction device to perform staged direct condensation of metal-rich flue gas; the demetallized flue gas after condensation is returned to the fluidized bed roasting device.

[0048] Furthermore, the system also includes an exhaust gas treatment device, which is connected to the drying and preheating device and the fluidized bed roasting device respectively, to purify the high-temperature flue gas discharged from the drying and preheating device. The purified solid dust enters the fluidized bed roasting device for fluidized bed roasting to remove cyanide and impurities.

[0049] The electric arc furnace smelting device includes an electric arc furnace body, graphite electrodes, and an iron tapping port at the bottom of the furnace; the upper part of the furnace body is provided with a pure iron outlet, and the lower part is provided with a gold-rich iron outlet; the gold-rich iron outlet is connected to a cooling and melting device.

[0050] The staged condensation device includes a first direct condenser, a second direct condenser, and a third direct condenser connected in series along the flue gas flow direction; the first direct condenser, the second direct condenser, and the third direct condenser respectively collect silver, zinc, and lead; each condenser is equipped with a temperature control unit to maintain the temperature in each condenser within the condensation temperature range of the corresponding metal.

[0051] Compared with existing methods, the present invention has the following advantages: This invention constructs a complete process technology system of "heat storage pre-reduction - hot pressing molding - electric arc melting - cooling melting and separation - staged direct condensation". It innovatively integrates the three core units of "hot pressing molding - electric arc melting", "cooling melting and separation" and "staged direct condensation". Hot pressing molding produces hot-pressed blocks to achieve "block instead of powder and hot material hot loading", cooling melting and separation is used to complete the efficient dissociation of gold and iron, and staged direct condensation is used to achieve selective capture of gaseous metals silver, lead and zinc, forming a complete full-component recovery technology chain.

[0052] The hot-pressed blocks obtained by the present invention are a safer form than pelletized iron. The hot-pressed block products have low porosity and low reactivity, making them convenient for safe transportation in the system and avoiding the risk of self-heating of powdered iron obtained by direct reduction.

[0053] This invention establishes a technical path for the synergistic separation of gas, liquid, and solid phases. It achieves the tiered separation of iron products through the stratified treatment of molten iron by electric arc melting. Combined with cooling melting and graded direct condensation technology, it realizes the efficient recovery of valuable elements in cyanide tailings and the full-scale resource utilization of waste. Attached Figure Description

[0054] Figure 1 This is a process flow diagram of the method for graded recovery of valuable components from cyanide tailings via fluidized bed thermal regeneration pre-reduction according to the present invention.

[0055] Figure 2 This is a schematic diagram of a cyanide tailings fluidized thermal regenerative pre-reduction valuable component graded recovery system according to the present invention.

[0056] Explanation of reference numerals in the attached figures In the diagram: 1-Feeding bin, 2-Feeding system, 3-Cyclone preheater, 4-Airlock valve, 5-Suspension heating calcining furnace, 6-Burn, 7-Cyclone separator, 8-Regenerative pre-reduction reactor, 9-Heating reduction reactor, 10-Hot pressing system, 11-Melting electric arc furnace, 12-Melting pool, 13-First direct condenser, 14-Second direct condenser, 15-Third direct condenser, 16-Gas station, 17-First condensing pump, 18-Second condensing pump, 19-Third condensing pump, 20-Fourth condensing pump, 21-Dust collector, 22-Fan, 23-Chimney. Detailed Implementation

[0057] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments described in this invention are only for further explanation and illustration, and not for limiting their application scope. Based on this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this invention.

[0058] like Figure 1 As shown, this invention provides a method for the graded recovery of valuable components from cyanide tailings through fluidized bed thermal regenerative pre-reduction. This method employs... Figure 2The system shown is as follows. The system includes: a drying and preheating unit for drying and preheating cyanide tailings; a fluidized bed roasting unit for fluidized bed roasting to remove cyanide and impurities from the cyanide tailings preheated by the drying and preheating unit; a fluidized bed regenerative pre-reduction unit connected to the fluidized bed roasting unit, utilizing the sensible heat of the roasting outlet material to perform fluidized bed regenerative pre-reduction on the cyanide-removed tailings, outputting gold-rich sponge iron and lead- and silver-containing metal-rich flue gas respectively; and a heating and reduction unit connected to the fluidized bed regenerative pre-reduction unit for heating and reducing gold-rich sponge iron, outputting heated and reduced gold-rich sponge iron and zinc-containing metal-rich flue gas respectively. The system comprises: a flue gas treatment unit; a hot pressing forming unit connected to a heating reduction unit to hot press the reduced gold-rich sponge iron into hot-pressed blocks; an electric arc furnace melting unit connected to the hot pressing forming unit to melt the hot-pressed blocks, separating and outputting pure iron, gold-rich iron, and slag; a cooling melting and precipitation unit connected to the electric arc furnace melting unit to cool and precipitate the gold-rich iron, separating and outputting a solid iron skeleton and a gold-rich liquid phase; a staged condensation unit connected to a fluidized bed regenerative pre-reduction unit to directly condense the metal-rich flue gas in stages; and a demetallized flue gas after condensation returned to the fluidized bed roasting unit. The system also includes a tail gas treatment unit connected to both the drying preheating unit and the fluidized bed roasting unit.

[0059] The system comprises the following components: a drying and preheating device, a feeding silo 1, a feeding system 2, and a cyclone preheater 3; a fluidized bed roasting device, an airlock valve 4, a suspension heating roasting furnace 5, a burner 6, and a cyclone separator 7; a fluidized bed regenerative pre-reduction device, a regenerative pre-reduction reactor 8; a heating reduction device, a heating reduction reactor 9; a hot pressing forming device, a hot pressing block system 10; an electric arc furnace melting device, a melting electric arc furnace 11; a cooling melting device, a melting pool 12; a staged condensing device, a first direct condenser 13, a second direct condenser 14, a third direct condenser 15, a gas station 16, a first condensing pump 17, a second condensing pump 18, a third condensing pump 19, and a fourth condensing pump 20; and a tail gas treatment device, a dust collector 21, a fan 22, and a chimney 23. The connection relationships between the components in this system are as follows: The feeding hopper 1 is connected to the inlet of the feeding system 2. The outlet of the feeding system 2 is connected to the inlet of the cyclone preheater 3 through a pipe. The lower outlet of the cyclone preheater 3 is connected to the air inlet of the airlock valve 4. The upper outlet of the cyclone preheater 3 is connected to the air inlet of the dust collector 21.

[0060] The outlet of the airlock valve 4 is connected to the inlet of the suspension heating roasting furnace 5. The outlet of the suspension heating roasting furnace 5 is connected to the inlet of the cyclone separator 7 through a pipeline. The upper air outlet of the cyclone separator 7 is connected to the air inlet of the feeding system 2.

[0061] The lower outlet of the cyclone separator 7 is connected to the inlet of the regenerative pre-reduction reactor 8. The outlet of the regenerative pre-reduction reactor 8 is connected to the inlet of the heating reduction reactor 9. The outlet of the heating reduction reactor 9 is connected to the inlet of the hot briquetting system 10. The outlet of the hot briquetting system 10 is connected to the inlet of the smelting electric arc furnace 11. The outlet of the smelting electric arc furnace 11 is connected to the inlet of the melting pool 12.

[0062] The reducing gas outlet of gas station 16 is connected to the inlet of first condensing pump 17 via a pipeline. The outlet of first condensing pump 17 is connected to the inlet of melting pool 12 via a pipeline. The outlet of melting pool 12 is connected to the reducing gas inlet of smelting electric arc furnace 11 via a pipeline. The outlet of smelting electric arc furnace 11 is connected to the protective gas inlet of hot press system 10 via a pipeline. The outlet of hot press system 10 is connected to the inlet of heating reduction reactor 9 via a pipeline. The outlet of heating reduction reactor 9 is connected to the inlet of regenerative pre-reduction reactor 8 via a pipeline.

[0063] The side outlet of the regenerative pre-reduction reactor 8 is connected to the bottom inlet of the first direct condenser 13. The top outlet of the first direct condenser 13 is connected to the bottom inlet of the second direct condenser 14. The top outlet of the second direct condenser 14 is connected to the bottom inlet of the third direct condenser 15. The top outlet of the third direct condenser 15 is connected to the bottom inlet of the suspension heating calciner 5.

[0064] The outlet of condensate gas I in gas station 16 is connected to the inlet of the second condensate pump 18 through a pipe. The outlet of the second condensate pump 18 is connected to the side inlet of the first direct condenser 13 through a pipe. The outlet of condensate gas II in gas station 16 is connected to the inlet of the third condensate pump 19 through a pipe. The outlet of the third condensate pump 19 is connected to the side inlet of the second direct condenser 14 through a pipe. The outlet of condensate gas III in gas station 16 is connected to the inlet of the fourth condensate pump 20 through a pipe. The outlet of the fourth condensate pump 20 is connected to the side inlet of the third direct condenser 15 through a pipe.

[0065] The discharge port of dust collector 21 is connected to the inlet of cyclone separator 7 through a pipe, the air outlet of dust collector 21 is connected to fan 22 through a pipe, and the air outlet of fan 22 is connected to chimney 23.

[0066] The bottom of the suspension heating roasting furnace 5 is equipped with a burner 6. The high-temperature gas generated by combustion inside the burner 6 can directly enter the system from the bottom of the suspension heating roasting furnace 5. Part of the high-temperature flue gas generated by the burner 6 is introduced into the heating reduction reactor 9 through a bypass pipe as a high-temperature heat source for the heating reduction reactor 9. The burner 6 is equipped with two air inlets, which are connected to coal gas and air respectively.

[0067] The method of this invention mainly includes the following: After drying and preheating, the cyanide tailings from gold smelting undergo fluidized bed roasting to remove cyanide and impurities such as cyanide ions, water of crystallization, and hydroxyl groups. Then, utilizing the heat carried by the cyanide tailings themselves, fluidized bed regenerative pre-reduction is performed to generate gold-rich sponge iron, while lead and silver are reduced to elemental metals and enter the gas phase. The gold-rich sponge iron is then heated and reduced, with zinc being reduced to elemental metals and entering the gas phase. The heated and reduced gold-rich sponge iron is hot-pressed into hot-pressed blocks, which are then smelted to separate the upper layer of pure molten iron, the lower layer of gold-rich molten iron, and slag. The gold-rich molten iron undergoes cooling and precipitation treatment, where iron is converted into a solid iron framework while gold remains in the liquid phase, achieving gold and iron separation. The metal-rich flue gas (rich in elemental metals) undergoes staged direct condensation treatment to separate silver, zinc, and lead. Ultimately, the separation and purification of multiple valuable components such as gold, silver, iron, zinc, and lead from the cyanide tailings are achieved.

[0068] The cyanide tailings contain gold grades of 0.2 g / t to 2 g / t, silver grades of 5 g / t to 50 g / t, iron grades of 20% to 50%, lead grades of 1% to 5%, and zinc grades of 0.3% to 7%.

[0069] The gas treatment process in the cyanide tailings treatment includes the following: Gas station 16 provides condensate gas and reducing gas. The condensate gas is mainly composed of nitrogen, and the reducing gas is mainly composed of converter gas and nitrogen. The volume fraction of CO in the converter gas is 45%–70%, and the total fraction of reducing gas (CO+H2+CH4) is not less than 50%. The reducing gas (a mixture of converter gas and nitrogen) is used for the cooling and melting treatment of gold-rich molten iron, providing a reducing atmosphere while absorbing heat from the gold-rich molten iron to form preheated reducing gas. The preheated reducing gas is first used for electric arc furnace smelting, providing a reducing atmosphere while further absorbing heat from the electric arc furnace smelting process, and then sequentially used for hot pressing, The heating reduction and heat storage pre-reduction treatment provides a reducing atmosphere while the heat from the preheating reducing gas is recovered and converted into metal-rich flue gas. The metal-rich flue gas undergoes staged condensation treatment with condenser gas, in which silver, zinc, and lead are successively condensed and recovered to form demetallized flue gas. The demetallized flue gas, together with the gas and air supplied by the burner, is combined at the bottom of the suspension heating roasting furnace for combustion and heat release. The high-temperature flue gas generated by the combustion is used in sequence for fluidized bed roasting of cyanide tailings to remove cyanide and impurities, and for drying and preheating treatment. The heat from the high-temperature flue gas is recovered and purified by dust removal before being discharged as tail gas. The heat generated by the combustion is also used for the heating reduction treatment of gold-rich sponge iron, as detailed in the following explanation of heat release reflux.

[0070] During system operation, a gas reflux occurs within a closed pipeline, serving as a heat transfer mechanism between the two stages: exothermic reflux. The high-temperature gas generated by burner 6 is introduced into the heating reduction reactor 9 via a bypass pipeline, providing additional heat for the heating reduction reaction as an auxiliary heat source. This heat transfer path is referred to as exothermic reflux in this invention. The waste heat generated by combustion, i.e., the heat remaining in the cavity of the equipment (such as the burner) that was not carried away by the high-temperature flue gas, is recovered through exothermic reflux and carried to the heating reduction stage, serving as a second heat source besides the preheating reducing gas, ensuring the smooth progress of the reduction reaction under specific temperature conditions.

[0071] The method of this invention can be used to recover valuable components from cyanide tailings, with gold recovery rate >99%, iron recovery rate >90%, silver recovery rate >90%, lead recovery rate >95%, and zinc recovery rate >95%.

[0072] This method first uses high-temperature flue gas returned from the system to preheat and dry the cyanide tailings. Then, it undergoes heating and decomposition in a suspended state, followed by fluidized bed roasting to remove cyanide, water of crystallization, hydroxyl groups, and other impurities, generating a relatively simple metal oxide. Subsequently, the mineral's own heat storage is utilized for regenerative pre-reduction in a suspended state, producing gold-rich sponge iron. The pre-reduced material enters a heating reduction stage to further reduce the volatile valuable metal components. The heated and reduced gold-rich sponge iron is then hot-pressed into blocks and sent to an electric arc furnace for smelting, yielding slag, upper layer molten iron, and lower layer gold-rich molten iron. The gold-rich molten iron is then subjected to cooling and precipitation treatment to separate the gold from the iron skeleton. Throughout the high-temperature reduction and smelting process, metals such as silver, lead, and zinc are reduced to vapor, which enters a staged direct condensation system with the flue gas, where they are sequentially condensed and collected at different temperatures to obtain high-purity silver powder, zinc powder, and lead powder. The coal gas and nitrogen supplied by the gas station are used as reducing gases. After being cooled and melted, they absorb heat from the gold-rich molten iron to form preheated reducing gas. This preheated reducing gas then undergoes electric furnace smelting, hot pressing, heating reduction, and regenerative pre-reduction treatments. Heat is gradually recovered, forming metal-rich flue gas. This metal-rich flue gas, along with the condensing gas (nitrogen) supplied by the gas station, undergoes staged direct condensation treatment. While the heat is recovered and utilized, silver, zinc, and lead in the flue gas are also condensed, recovered, and converted into demetallized flue gas. This demetallized flue gas is then combined with converter gas and air for combustion and heat release. The generated heat is used for heating and reducing the gold-rich sponge iron. The resulting high-temperature flue gas is first used for fluidized bed roasting to remove cyanide and impurities, then for drying and preheating cyanide tailings, and finally, after dust removal and purification, it is emitted as exhaust gas. Thus, the multi-stage high-temperature flue gas and reducing gas generated in the system are all recycled, forming a complete energy and material recovery network. The slag can be used to produce ceramic glass, cement-based composite materials and other building materials, thereby realizing the removal of cyanide and impurities from cyanide tailings and the comprehensive utilization of various valuable components such as gold, silver, iron, lead and zinc.

[0073] The method of the present invention includes the following specific contents: (1) Drying and preheating: The cyanide tailings stored in the feed silo 1 are sent to the feed system 2, where they are screened and crushed to ensure that their particle size is less than 1 mm. Subsequently, the cyanide tailings powder and the high-temperature flue gas separated and returned from the cyclone separator 7 are fully mixed in the feed system 2. Under the action of the flue gas flow, the cyanide tailings are transported to the cyclone preheater 3 through the pipeline. In the cyclone preheater 3, high-temperature flue gas is introduced to form a fluidized environment to dry and preheat the cyanide tailings. The drying and dehydration temperature is 150℃~200℃, and the residence time is 10s~20s. The moisture content in the pretreated cyanide tailings is controlled below 1%. The material is discharged into the suspension heating roasting furnace 5 through the air lock valve 4. The high-temperature flue gas that has completed the heat exchange is then sent to the dust collector 21 for purification treatment as tail gas.

[0074] (2) Fluidized bed roasting for cyanide removal and impurity removal: The preheated cyanide tailings are fed into a suspension heating roasting furnace 5. Air, converter gas, and demetallization flue gas returned from staged direct condensation are introduced into the burner 6 located at the bottom of the suspension heating roasting furnace 5 and ignited for combustion and heat release. The volume concentration of converter gas is 20% to 40%, and high-temperature flue gas is formed by combustion. This flue gas is fed into the suspension heating roasting furnace 5 from the bottom, so that the cyanide tailings ore powder is in a suspended state for fluidized bed roasting for cyanide removal and impurity removal. The furnace temperature is 1100℃ to 1200℃, and the roasting time is 10s to 20s. The furnace temperature is stabilized to oxidize the cyanide tailings and remove impurities such as cyanide ions, water of crystallization, and hydroxyl groups. The cyanide removal rate is greater than 99.99%. The main reactions that occur are as follows: FeO·OH(s) → Fe2O3(s) + H2O(g); Al2Si2O5(OH)4(s) → Al2O3·2SiO2(s) + H2O(g); MeCO3(s) → MeO(g) + CO2(g) (Me = Pb, Zn); C(s) + O2(g) → CO2(g); CN - + O2→ CO2+ N2+ O 2- ; SCN - + O2→ SO2+ CO2+ N2+ O 2- ; MeS(s) + O2(g) → MeO(s) + SO2(g) (Me = Pb, Zn); Me2S(s) + O2(g) → Me2O(s) + SO2(g) (Me = Ag, Au); SO2(g) + O2(g) → SO3(g); Fe4[Fe(CN)6]3(s) + O2(g) → Fe2O3(s) + CO2(g) + N2(g); MeO(s) + SO3(g) → MeSO4(s) (Me = Pb, Zn).

[0075] After fluidized bed roasting to remove cyanide and impurities, the material undergoes gas-solid separation in cyclone separator 7. The high-temperature flue gas is returned to the feeding system 2 for drying and preheating of cyanide tailings, while the solid material is sent to the regenerative pre-reduction reactor 8 for further processing.

[0076] (3) Regenerative Pre-reduction: The material discharged from the cyclone separator 7 is fed into the regenerative pre-reduction reactor 8. Preheated reducing gas returned from heating and reduction is introduced into the bottom of the regenerative pre-reduction reactor 8, which is a mixture of nitrogen and converter gas prepared in a specific ratio (the amount of converter gas introduced into the mixture is based on the mass ratio of the total volume of reducing gas in the converter gas to the cyanide tailings powder in the reduction roaster being 0.4 m). 3 / kg~1.2m 3 (Calculated per kg). The regenerative pre-reduction reactor 8 utilizes the heat stored within the mineral itself, allowing the powder to undergo a reduction reaction with the mixed gas in a suspended state, generating gold-rich sponge iron with an iron metallization rate of 65%–95%. The fluidized bed regenerative pre-reduction temperature is controlled at 800℃–950℃, and the reaction time is 20 min–60 min. The main reactions that occur are as follows: Fe2O3+ CO(g) → Fe3O4+ CO2(g); Fe3O4+ CO(g) → FeO + CO2(g); FeO + CO(g) → Fe + CO2(g); O2(g) + CO(g) → CO2(g); Fe2O3+ H2(g) → Fe3O4+ H2O(g); Fe3O4+ H2(g) → FeO + H2O(g); FeO + H2(g) → Fe + H2O(g); O2(g) + H2(g) → H2O(g).

[0077] In cyanide tailings, lead and silver minerals are reduced to elemental metals under a reducing atmosphere and enter the gas phase, escaping with the flue gas to a staged condenser. The main reactions are as follows: PbSO4+ CO(g) → Pb(g) + CO2(g) + SO2(g); PbSiO3+ CO(g) → Pb(g) + SiO2+ CO2(g); PbFe2O4+ CO(g) → FeO + PbO + CO2(g); PbO + CO(g) → Pb(g) + CO2(g); PbSO4+ H2(g) → Pb(g) + H2O(g) + SO2(g); PbSiO3+ H2(g) → Pb(g) + SiO2+ H2O(g); PbFe2O4+ H2(g) → FeO + PbO + H2O(g); PbO + H2(g) → Pb(g) + H2O(g); Ag2O + CO(g) → Ag(g) + CO2(g); Ag2O + H2(g) → Ag(g) + H2O.

[0078] (4) Heating and Reduction: The gold-rich sponge iron after regenerative pre-reduction enters the heating and reduction reactor 9. The heating and reduction temperature is controlled at 950℃~1200℃, and the reaction time is 20min~60min. The heat source is one exothermic reflux of the burner 6, and the reducing gas source is the preheated reducing gas returned from the hot press system 10. The zinc-containing minerals in the cyanide tailings are reduced to elemental metals under a reducing atmosphere and enter the gas phase. They escape with the preheated reducing gas to the regenerative pre-reduction reactor 8 and finally enter the staged condenser. The main reactions are as follows: ZnSO4+ CO(g) → Zn(g) + CO2(g) + SO2(g); ZnSiO3+ CO(g) → Zn(g) + SiO2+ CO2(g); ZnFe2O4+ CO(g) → FeO + ZnO + CO2(g); ZnO + CO(g) → Zn(g) + CO2(g); ZnSO4+ H2(g) → Zn(g) + H2O(g) + SO2(g); ZnSiO3+ H2(g) → Zn(g) + SiO2+ H2O(g); ZnFe2O4+ H2(g) → FeO + ZnO + H2O(g); ZnO + H2(g) → Zn(g) + H2O(g).

[0079] (5) Hot pressing: The heated and reduced gold-rich sponge iron enters the hot pressing system 10 for hot pressing. Under the protection of the preheated reducing gas returned from the melting electric arc furnace 11, the material is kept hot and pressed into round cake-shaped blocks with a diameter of 80mm to 120mm and a height of 20mm. The hot pressing temperature is 600℃ to 800℃; the hot pressing pressure is 200MPa to 400MPa; the hot pressing time is 5min to 15min; the iron metallization rate in the hot pressing block is not less than 65%; the density of the hot pressing block is 4.5 to 5.5g / cm³. 3 The molded block has a uniform internal structure and excellent high-temperature mechanical properties, which can meet the strength requirements of the furnace charge in subsequent smelting processes. The pressed block is fed into the smelting electric arc furnace 11, and after the preheating reducing gas is discharged, it enters the heating reduction reactor 9.

[0080] (6) Electric Arc Furnace Melting: The hot briquettes are directly fed into the electric arc furnace 11 for melting, using the preheated reducing gas returned from the molten pool 12 as a reducing agent. The melting temperature is 1350℃~1600℃, and the melting time is 30min~50min. Only necessary slag-forming agents are added during the melting process, using a combination of lime, dolomite, fluorite, iron ore, and coke powder. The metal phase and slag phase are fully separated, and the molten iron is also significantly stratified due to the different component densities. The upper layer of pure molten iron is discharged directly from the upper molten iron nozzle as pure molten iron product, while the lower layer of gold-rich molten iron product is discharged from the lower molten iron nozzle and discharged into the molten pool 12 for further processing. The molten slag is separated and discharged from the slag outlet. The preheated reducing gas is further preheated and heated while acting as a protective gas, and then introduced into the hot briquette system 10.

[0081] (7) Cooling and Melting: Gas station 16 provides reducing gas (coal gas + nitrogen), which is pressurized by the first condenser pump 17 to become low-temperature reducing gas and sent to the melting pool 12. Gold-rich molten iron is fed into the melting pool 12. Under the blowing of the low-temperature reducing gas supplied by gas station 16, the temperature of the gold-rich molten iron is controlled to drop to 900℃~1100℃ by adjusting the flow rates of the feed and discharge gas and the temperature of the gas at the outlet of the first condenser pump 17. The iron in the melting pool 12 is converted into a solid porous iron skeleton, while the gold remains in a liquid state and flows out from the gaps in the iron skeleton, completing the separation of gold and iron. The reducing gas absorbs the heat from the gold-rich molten iron and is converted into preheated reducing gas before returning to the smelting electric arc furnace 11.

[0082] (8) Staged Direct Condensation: The metal-rich flue gas enters the staged condensation device. The low-temperature condensing gas built into the first direct condenser 13, the second direct condenser 14, and the third direct condenser 15 is pressurized and cooled by the second condensing pump 18, the third condensing pump 19, and the fourth condensing pump 20, respectively. The condensing gas is uniformly supplied from the gas station 16. In the first direct condenser 13, silver metal vapor condenses into solid silver metal powder at a temperature of 900℃~1000℃ and is sealed and discharged. In the second direct condenser 14, zinc metal vapor condenses into solid zinc metal powder at a temperature of 550℃~750℃ and is sealed and discharged. In the third direct condenser 15, lead metal vapor condenses into solid lead metal powder at a temperature of 350℃~420℃ and is sealed and discharged. The demetallized flue gas obtained by the three-stage condensation still has a large amount of combustible reducing gas and nitrogen, which is returned to the bottom air inlet of the suspension heating roasting furnace 5 to participate in the mixed combustion of the gas fed into the burner 6 for secondary utilization.

[0083] (9) Tail gas treatment: The high-temperature flue gas after drying and preheating of cyanide tail residue is used as tail gas and is introduced into dust collector 21 for purification. The separated gas is discharged from the outlet of dust collector 21 and the purified gas is discharged from the system through chimney 23 by fan 22. The solid dust obtained by dust collector 21 is discharged into cyclone separator 7 from its lower outlet. After fluidized roasting to remove cyanide and impurities together with the main material, it enters the regenerative pre-reduction reactor 8 and recovers valuable components together with the main material. Finally, it enters various products or forms electric arc furnace slag.

[0084] This invention enables fluidized coordinated operation of the entire system, allowing for efficient mass and heat transfer between the gas and solid phases, significantly improving the reaction rate and metal recovery efficiency, and providing a reliable foundation for engineering scale-up.

[0085] This invention constructs an energy network for multi-stage waste heat and reducing gas circulation, integrates a drying and preheating subsystem, achieves material preheating through high-temperature flue gas flow, and recycles the waste heat and condensed flue gas from each process step as a heat source or protective gas, significantly reducing the consumption of external energy and media.

[0086] This invention integrates fluidized bed roasting for cyanide removal and impurity elimination with precise atmosphere control. During suspension roasting, it simultaneously removes impurities such as cyanide and performs directional phase transformation. It utilizes the material's own heat storage for reduction reactions and optimizes the reducing atmosphere by precisely controlling the composition of the reducing gas, thus achieving efficient and clean smelting.

[0087] The slag-forming agents used in the following examples and comparative examples mainly consist of lime, dolomite, fluorite, etc., and the dosage range of the slag-forming agent is 0.5%wt. to 1.5%wt. The components are combined and formulated as needed; for details, please refer to patents CN119800085A and CN110157972A, etc.

[0088] Example 1 This embodiment processes a cyanide tailings with the following composition (mass percentage): Au 1.2 g / t, Ag 28 g / t, Fe 42%, Pb 2.5%, Zn 4.8%, and the remaining components are non-metallic. The feed particle size of the cyanide tailings is P80 = 28 mm.

[0089] (1) Drying and preheating: The cyanide tailings are ground to a particle size of less than 1 mm in the feeding system, mixed with the high-temperature flue gas returned from the cyclone separator and transported to the cyclone preheater. The temperature is controlled at 200℃ and the residence time is 15s. After drying and preheating, the moisture content of the cyanide tailings is <1%.

[0090] (2) Fluidized roasting for decyanation and impurity removal: The dried and preheated cyanide tailings are fed into a suspension heating roasting furnace. Air and converter gas are introduced into the burner located at the bottom of the suspension heating roasting furnace and combined with the demetallized flue gas returned by direct condensation in stages for combustion and heat release. The converter gas volume concentration is 35%, the roasting temperature is 1180℃, the roasting time is 15s, and the decyanation rate is >99.99%.

[0091] (3) Regenerative Pre-reduction: The material after cyanide removal and impurity removal undergoes gas-solid separation via a cyclone separator. The separated solid material is then fed into the regenerative pre-reduction reactor, through which a mixture of nitrogen and converter gas (converter gas flow rate 0.85m³) is introduced. 3 The reaction was carried out at 950℃ for 45 minutes, producing gold-rich sponge iron and lead- and silver-rich metal-rich flue gas, with an iron metallization rate of approximately 90%. The separated high-temperature flue gas was returned to the feeding system to dry and preheat the cyanide tailings.

[0092] (4) Heating reduction: The gold-rich sponge iron generated after heat storage pre-reduction enters the heating reduction reactor. The reaction temperature is 1000℃ and the reaction time is 40min. The heat source is the heat release reflux of the burner. The reducing gas is the preheated reducing gas returned by the hot press block. The heated gold-rich sponge iron and zinc-containing metal-rich flue gas are obtained. The zinc-containing metal-rich flue gas enters the heat storage pre-reduction reactor together with the preheated reducing gas.

[0093] (5) Hot-pressed block: The reduced gold-rich sponge iron was hot-pressed at 700℃ and 300MPa for 10 minutes to form a round, disc-shaped block with a diameter of 110mm and a height of 20mm, and a density of 4.5g / cm³. 3 .

[0094] (6) Electric arc furnace smelting: A round, 110 mm in diameter and 20 mm in height is smelted in an electric arc furnace at a temperature of 1350 °C for 45 min. A slag-forming agent of 0.8% wt. is added to separate pure iron, gold-rich iron and slag.

[0095] (7) Cooling and melting: The gold-rich molten iron is transported to the melting pool and its temperature is reduced to 1000℃. The iron solidifies into a porous skeleton and the gold liquid phase flows out.

[0096] (8) Staged direct condensation: Metal-rich flue gas containing lead and silver, as well as metal-rich flue gas containing zinc, are discharged from the gas outlet of the regenerative pre-reduction reactor to multiple direct condensers. Ag is condensed at 950°C in the first direct condenser, Zn is condensed at 600°C in the second direct condenser, and Pb is condensed at 400°C in the third direct condenser. The demetallized flue gas after condensation is sent to the bottom of the suspension heating roasting furnace.

[0097] (9) Exhaust gas treatment: The exhaust gas in the cyclone preheater is purified by a dust collector before being discharged, and the solid dust is recycled.

[0098] The final product specifications for this embodiment are: gold recovery rate 99.3%, silver recovery rate 91.8%, iron recovery rate 92.5%, lead recovery rate 96.5%, and zinc recovery rate 97.2%.

[0099] Example 2 This embodiment processes a cyanide tailings with the following composition (mass percentage): Au 0.8 g / t, Ag 35 g / t, Fe 38%, Pb 3.8%, Zn 6.5%, and the remainder being non-metallic components. The feed particle size of the cyanide tailings is P80 = 25 mm. The difference from Example 1 is: (1) Drying and preheating: temperature 180℃, residence time 18s.

[0100] (2) Fluidized roasting for decyanation and impurity removal: converter gas volume concentration 32%, temperature 1150℃, roasting time 18s.

[0101] (3) Regenerative pre-reduction: Converter gas feed rate 0.75m³ 3 / kg, temperature 920℃, reaction time 50min, iron metallization rate is about 92%.

[0102] (4) Heating reduction: temperature 1050℃, reaction time 45min.

[0103] (5) Hot-pressed block: a round, disc-shaped block with a diameter of 95 mm and a height of 20 mm, hot-pressed at a temperature of 750℃, a pressure of 350 MPa, and a time of 12 min, with a density of 4.9 g / cm³. 3 .

[0104] (6) Electric arc furnace smelting: temperature 1400℃, time 40min, add 1.0wt.% slagging agent.

[0105] (7) Cooling and melting: The temperature of the gold-rich molten iron is reduced to 950℃.

[0106] (8) Staged direct condensation: Ag condenses at 920℃, Zn condenses at 650℃, and Pb condenses at 380℃.

[0107] The final product specifications for this embodiment are: gold recovery rate 99.1%, silver recovery rate 92.5%, iron recovery rate 91.0%, lead recovery rate 97.8%, and zinc recovery rate 98.1%.

[0108] Example 3 This embodiment processes a cyanide tailings with the following composition (mass percentage): Au 1.5 g / t, Ag 22 g / t, Fe 35%, Pb 2.0%, Zn 5.5%, with the remainder being non-metallic components. The feed particle size of the cyanide tailings is P80 = 30 mm. The difference from Example 1 is: (1) Drying and preheating: temperature 160℃, residence time 12s.

[0109] (2) Fluidized roasting for decyanation and impurity removal: coal gas volume concentration 38%, temperature 1200℃, roasting time 12s.

[0110] (3) Thermal pre-reduction: Gas flow rate 0.95m 3 / kg, temperature 880℃, reaction time 35min, iron metallization rate is about 80%.

[0111] (4) Heating reduction: temperature 1100℃, reaction time 35min.

[0112] (5) Hot-pressed block: a round, disc-shaped block with a diameter of 120 mm and a height of 20 mm, hot-pressed at a temperature of 650℃, a pressure of 250 MPa, and a time of 8 min, with a density of 4.7 g / cm³. 3 .

[0113] (6) Electric arc furnace smelting: temperature 1450℃, time 35min, add 0.6wt.% slagging agent.

[0114] (7) Cooling and melting: The temperature of the gold-rich molten iron is reduced to 900℃.

[0115] (8) Staged direct condensation: Ag condenses at 980℃, Zn condenses at 700℃, and Pb condenses at 360℃.

[0116] The final product specifications for this embodiment are: gold recovery rate 99.4%, silver recovery rate 91.2%, iron recovery rate 90.8%, lead recovery rate 96.2%, and zinc recovery rate 97.5%.

[0117] Example 4 This embodiment processes a cyanide tailings with the following composition (mass percentage): Au 0.5 g / t, Ag 18 g / t, Fe 45%, Pb 1.5%, Zn 3.2%, and the remainder being non-metallic components. The feed particle size of the cyanide tailings is P80 = 22 mm. The difference from Example 1 is: (1) Drying preheating: temperature 150℃, residence time 16s.

[0118] (2) Fluidized roasting for decyanation and impurity removal: coal gas volume concentration 30%, temperature 1120℃, roasting time 16s.

[0119] (3) Thermal pre-reduction: Gas flow rate 0.65m 3 / kg, temperature 800℃, reaction time 55min, iron metallization rate is about 75%.

[0120] (4) Heating reduction: temperature 950℃, reaction time 50min.

[0121] (5) Hot-pressed block: a round, disc-shaped block with a diameter of 85 mm and a height of 20 mm, hot-pressed at a temperature of 800℃, a pressure of 400 MPa, and a time of 15 min, with a density of 6.0 g / cm³. 3 .

[0122] (6) Electric arc furnace smelting: temperature 1500℃, time 48min, add 1.5wt.% slag-forming agent.

[0123] (7) Cooling and melting: The temperature of the gold-rich molten iron is reduced to 1050℃.

[0124] (8) Staged direct condensation: Ag condenses at 900℃, Zn condenses at 550℃, and Pb condenses at 420℃.

[0125] The final product specifications for this embodiment are: gold recovery rate 99.2%, silver recovery rate 90.8%, iron recovery rate 93.2%, lead recovery rate 95.8%, and zinc recovery rate 96.9%.

[0126] Example 5 This embodiment processes a cyanide tailings with the following composition (mass percentage): Au 1.0 g / t, Ag 25 g / t, Fe 40%, Pb 2.2%, Zn 4.5%, with the remainder being non-metallic components. The feed particle size of the cyanide tailings is P80 = 26 mm. The difference from Example 1 is: (1) Drying and preheating: temperature 150℃, residence time 10s.

[0127] (2) Fluidized roasting for decyanation and impurity removal: gas volume concentration 20%, temperature 1100℃, roasting time 10s.

[0128] (3) Thermal pre-reduction: Gas flow rate 0.4 m³ / s 3 / kg, temperature 800℃, reaction time 20min, iron metallization rate is about 65%.

[0129] (4) Heating reduction: temperature 950℃, reaction time 20min.

[0130] (5) Hot-pressed block: a round, disc-shaped block with a diameter of 80 mm and a thickness of 20 mm, hot-pressed at a temperature of 600℃, a pressure of 200 MPa, and a time of 5 min, with a density of 5.5 g / cm³. 3 .

[0131] (6) Electric arc furnace smelting: temperature 1350℃, time 30min, add 0.5wt.% slag-forming agent.

[0132] (7) Cooling and melting: The temperature of the gold-rich molten iron is reduced to 900℃.

[0133] (8) Staged direct condensation: Ag condenses at 900℃, Zn condenses at 550℃, and Pb condenses at 350℃.

[0134] The final product specifications for this embodiment are: gold recovery rate 99.0%, silver recovery rate 90.2%, iron recovery rate 90.5%, lead recovery rate 95.1%, and zinc recovery rate 95.3%.

[0135] Example 6 This embodiment processes a cyanide tailings with the following composition (mass percentage): Au 1.8 g / t, Ag 45 g / t, Fe 48%, Pb 4.5%, Zn 6.8%, and the remainder being non-metallic components. The feed particle size of the cyanide tailings is P80 = 29 mm. The difference from Example 1 is: (1) Drying and preheating: temperature 200℃, residence time 20s.

[0136] (2) Fluidized roasting for decyanation and impurity removal: gas volume concentration 40%, temperature 1200℃, roasting time 20s.

[0137] (3) Thermal pre-reduction: Gas flow rate 1.2m³ 3 / kg, temperature 950℃, reaction time 60min, iron metallization rate is about 95%.

[0138] (4) Heating reduction: temperature 1200℃, reaction time 60min.

[0139] (5) Hot-pressed block: a round, disc-shaped block with a diameter of 120 mm and a thickness of 20 mm, hot-pressed at a temperature of 780℃, a pressure of 380 MPa, and a time of 14 min, with a density of 5.0 g / cm³. 3 .

[0140] (6) Electric arc furnace smelting: temperature 1600℃, time 50min, add 1.2wt.% slag-forming agent.

[0141] (7) Cooling and melting: The temperature of the gold-rich molten iron is reduced to 1100℃.

[0142] (8) Staged direct condensation: Ag condenses at 1000℃, Zn condenses at 750℃, and Pb condenses at 420℃.

[0143] The final product specifications for this embodiment are: gold recovery rate 99.5%, silver recovery rate 92.8%, iron recovery rate 93.0%, lead recovery rate 97.5%, and zinc recovery rate 98.2%.

[0144] Comparative Example 1 (Drying without flue gas flow carrier) The only difference from Example 1 is that, in the drying preheating stage, instead of using the high-temperature flue gas returned from the cyclone separator to mix with and transport the material, hot air generated by a conventional hot air furnace is used for drying, and then directly fed into the next process via a screw feeder. After drying, the moisture content of the material is as high as 8.5%, which is far beyond the control range, resulting in the obstruction of subsequent fluidization.

[0145] Final product specifications: Gold recovery rate 65.3%, Silver recovery rate 41.2%, Iron recovery rate 52.7%, Lead recovery rate 33.6%, Zinc recovery rate 28.9%.

[0146] Comparing the results of Example 1 and Comparative Example 1, it is evident that Comparative Example 1, by using conventional hot air drying instead of high-temperature flue gas flow mixing, resulted in extremely poor material dehydration, with a moisture content exceeding 8%, significantly exceeding the control range of this invention. This high moisture content led to material adhesion and fluidization obstruction during subsequent fluidized bed roasting, hindering the complete decyanation reaction. The decyanation rate plummeted from the expected 99.99% or higher to approximately 82%. Simultaneously, the reduction reaction was also severely hampered, ultimately resulting in a valuable metal recovery rate of less than 70%, far below the technical specifications of >99% for gold, >90% for iron, >90% for silver, >95% for lead, and >95% for zinc required by this invention. This demonstrates that the flue gas flow drying preheating method employed in this invention plays a decisive role in ensuring the efficiency of subsequent processes and the high-efficiency recovery of valuable metals.

[0147] Comparative Example 2 (the hot press step is omitted) The only difference from Example 1 is that the gold-rich sponge iron after heating and reduction is fed directly into the electric arc furnace for melting without being hot-pressed. To maintain the supply of reducing gas for the heating and reduction step, preheated reducing gas with the same flow rate and composition as the hot-pressed return gas is supplied directly to the heating and reduction reactor from the gas station.

[0148] Final product specifications: Gold recovery rate 72.1%, Silver recovery rate 63.5%, Iron recovery rate 48.3%, Lead recovery rate 54.7%, Zinc recovery rate 46.2%.

[0149] Comparing the results of Example 1 and Comparative Example 2, it is evident that when the hot pressing step is omitted, the loose sponge iron is directly fed into the furnace and is largely carried away by the high-temperature flue gas in the electric arc furnace, forming highly reactive iron-containing dust. This type of dust has a large specific surface area and high reactivity, making it extremely prone to self-heating in the dust removal system or material transfer process, and may even cause combustion or explosion accidents, posing serious safety hazards to the system. Simultaneously, due to the extreme instability of the molten pool, the reducing atmosphere is difficult to maintain, leading to a sharp decline in metal recovery rates. The iron recovery rate plummeted from 92.5% to 48.3%, and the recovery rates of gold, silver, lead, and zinc also dropped significantly to below 73%, completely failing to meet the indicators specified in this invention. This indicates that hot pressing not only compresses sponge iron into a safe block with low porosity and low reactivity, avoiding the risk of self-heating of powdered iron, but is also a crucial step in ensuring smelting efficiency and efficient recovery of valuable metals.

[0150] Comparative Example 3 (lacking low-temperature reducing gas and forced cooling melting) The only difference from Example 1 is that during the cooling and melting stage, no low-temperature reducing gas was provided, that is, there was no reducing gas blowing and cooling in the melting pool. The gold-rich molten iron cooled naturally, and the temperature dropped slowly. Eventually, the molten iron solidified into a whole block, and the gold could not be separated.

[0151] Final product specifications: Gold recovery rate 15.3%, Silver recovery rate 90.5%, Iron recovery rate 91.2%, Lead recovery rate 95.8%, Zinc recovery rate 96.1%.

[0152] Comparing the results of Example 1 and Comparative Example 3, it can be seen that when no low-temperature reducing gas is provided in the cooling and melting step, the molten iron slowly solidifies into a solid block due to the lack of forced cooling. Gold cannot fully flow out from the iron skeleton, and most of the gold remains in the iron skeleton (testing showed that the gold residue in the iron skeleton product was as high as 1.6 g / t). This results in the inability to separate gold and iron, ultimately leading to a gold recovery rate of only 15.3%, far below the 99% or higher required by this invention. Simultaneously, the natural cooling process prolongs the processing time, and the iron skeleton becomes loose and porous, resulting in a decline in quality. While the recovery rates of other metals are close to those of Example 1, the overall effect has lost the core value of this invention. This indicates that forced cooling with low-temperature reducing gas is a necessary condition for achieving efficient gold separation and ensuring product quality and processing efficiency.

[0153] In summary, this invention achieves efficient recovery of valuable metals through optimized design of key steps (flue gas drying, hot pressing, and cooling melting). Any scheme that omits or simplifies these steps will result in a significant decrease in recovery rate and fail to achieve the expected results.

[0154] This invention proposes a fluidized bed recovery method and system for valuable components in cyanide tailings based on regenerative pre-reduction-hot pressing-electric arc furnace smelting-melting-gradual direct condensation. This method achieves efficient and synergistic extraction of multiple valuable components such as gold, silver, iron, lead, and zinc from cyanide tailings, providing a novel technical solution for the large-scale and high-value utilization of cyanide tailings.

[0155] The above-described embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A method for the graded recovery of valuable components from fluidized bed thermal regenerative pre-reduction of cyanide tailings, characterized in that, Includes the following steps: S1. After drying and preheating, the cyanide tailings are subjected to fluidized bed roasting to remove cyanide and impurities, resulting in cyanide-removed tailings. S2. Utilize the heat carried by the cyanide removal tailings obtained in S1 for fluidized bed regenerative pre-reduction to obtain gold-rich sponge iron and metal-rich flue gas. S3. The gold-rich sponge iron obtained in S2 is heated and reduced to obtain heated and reduced gold-rich sponge iron and metal-rich flue gas. S4. The gold-rich sponge iron obtained from S3 after heating and reduction is hot-pressed into a hot-pressed block, and the hot-pressed block is then subjected to electric arc melting to separate pure iron and gold-rich iron. S5. The gold-rich molten iron obtained in S4 is subjected to cooling and melting treatment to separate the gold from the iron. S6. The metal-rich flue gas obtained from S2 and S3 is directly condensed in stages.

2. The method according to claim 1, characterized in that, The particle size of the dried and preheated cyanide tailings in step S1 is <1 mm; Furthermore, the drying preheating temperature is 150℃~200℃; Furthermore, the drying preheating time is 10s to 20s; Furthermore, the moisture content of the cyanide tailings after drying and preheating is ≤1%; Furthermore, the fluidized roasting decyanation and impurity removal described in step S1 is carried out in the roasting gas; Furthermore, the roasting gas includes air and coal gas, wherein the volume concentration of the coal gas is 20% to 40%. Furthermore, the gas is converter gas; Furthermore, the calcination temperature for fluidized bed roasting to remove cyanide and impurities is 1100℃~1200℃; Furthermore, the calcination time for fluidized bed roasting to remove cyanide and impurities is 10s to 20s; Furthermore, the impurities removed in step S1 include cyanide, water of crystallization, and hydroxyl groups.

3. The method according to claim 1, characterized in that, The fluidized thermal storage pre-reduction described in step S2 is carried out in preheated reducing gas, which is the gas returned from the heating and reduction process in step S3. Furthermore, the preheating reducing gas includes nitrogen and coal gas, and the coal gas flow rate is based on a ratio of the total volume of reducing gases in the coal gas to the mass of cyanide tailings powder of approximately 0.4 m³. 3 / kg~1.2m 3 / kg; Furthermore, the temperature for the fluidized thermal regeneration pre-reduction is 800℃~950℃; Furthermore, the fluidized bed thermal regeneration pre-reduction time is 20 min to 60 min; Furthermore, the metal-rich flue gas contains lead and silver, which are reduced to elemental metals and volatilized into the gas phase during the fluidized regenerative pre-reduction process. The resulting gold-rich sponge iron has an iron metallization rate of 65% to 95%.

4. The method according to claim 1, characterized in that, The heating and reduction described in step S3 is carried out in preheated reducing gas and calcination gas; the preheated reducing gas is the gas returned from the hot pressing process in step S4, and the calcination gas is the exothermic reflux gas from the fluidized roasting decyanation and impurity removal process in step S1. Furthermore, the preheating reducing gas includes nitrogen and coal gas, and the roasting gas includes air and coal gas; Furthermore, the temperature for the heating reduction is 950–1200°C; Furthermore, the heating and reduction time is 20 min to 60 min; Furthermore, the metal-rich flue gas after heating and reduction contains zinc. During the heating and reduction process, the zinc is reduced to a metallic element and volatilizes into the gas phase. The iron metallization rate in the resulting metal-rich sponge iron after heating and reduction is 65% to 95%.

5. The method according to claim 1, characterized in that, The hot pressing process described in step S4 is carried out in a preheated reducing gas; the preheated reducing gas is the gas returned from the electric arc melting process described in step S4. Furthermore, the hot pressing temperature is 600℃~800℃; Furthermore, the pressure for hot pressing is 200MPa to 400MPa; Furthermore, the hot pressing time is 5 min to 15 min; Furthermore, the iron metallization rate in the hot-pressed block is not less than 65%; Furthermore, the density of the hot-pressed block is 4.5–5.5 g / cm³. 3 ; Furthermore, the arc melting described in step S4 is carried out in a preheated reducing gas; the preheated reducing gas is the gas returned from the cooling melting process in step S5. Furthermore, the temperature of the electric arc melting is 1350℃~1600℃; Furthermore, the arc melting time is 30 min to 50 min; Furthermore, the iron content in the molten iron is not less than 98 wt%. Furthermore, the enrichment factor of gold in the gold-rich molten iron is not less than 10 times.

6. The method according to claim 1, characterized in that, The cooling and melting process described in step S5 is carried out in reducing gas; after absorbing the heat from the gold-rich molten iron, the reducing gas is converted into preheated reducing gas and returned to the electric arc melting process in step S4. Furthermore, the reducing gas includes nitrogen and coal gas; Furthermore, the cooling and melting process lowers the temperature of the gold-rich molten iron to 900℃~1100℃. Within this temperature range, iron is transformed into a solid iron skeleton while gold remains in the liquid phase, thus achieving the separation of gold and iron through solid-liquid separation.

7. The method according to claim 1, characterized in that, In step S6, the staged direct condensation is carried out in the condensate gas according to the difference in dew point temperature of silver, zinc and lead. The separated metal-rich flue gas is converted into demetallized flue gas and returned to the fluidized roasting decyanation and impurity removal process in step S1. Furthermore, the condensate includes nitrogen; Furthermore, the silver is condensed and precipitated in the high-temperature condensation section at 900℃~1000℃; Furthermore, the zinc is condensed and precipitated in the medium-temperature condensation section at 550℃~750℃; Furthermore, the lead is condensed and precipitated in the low-temperature condensation section at 350°C to 420°C.

8. The method according to claim 1, characterized in that, It also includes S7, exhaust gas treatment: the high-temperature flue gas in the cyanide tailings drying and preheating process in step S1 is used as exhaust gas for purification treatment, the solid dust obtained after purification is fluidized roasting to remove cyanide and impurities, and the purified gas is discharged from the system.

9. A fluidized bed thermal regenerative pre-reduction system for the graded recovery of valuable components from cyanide tailings, characterized in that, include: A drying and preheating device is used to dry and preheat cyanide tailings using high-temperature flue gas returned from the system. A fluidized bed roasting apparatus, connected to the drying and preheating apparatus, is used to perform fluidized bed roasting to remove cyanide and impurities from the preheated cyanide tailings. A fluidized bed regenerative pre-reduction device is connected to the fluidized bed roasting device. It uses the sensible heat of the roasting outlet material to perform fluidized bed regenerative pre-reduction on the cyanide removal tailings, and outputs gold-rich sponge iron and metal-rich flue gas respectively. The heating and reduction device is connected to the fluidized heat storage pre-reduction device to heat and reduce the gold-rich sponge iron, and outputs the heated and reduced gold-rich sponge iron and the metal-rich flue gas respectively. A hot pressing forming device is connected to the heating and reduction device to hot press gold-rich sponge iron into hot pressing blocks. An electric arc furnace melting device is connected to the hot pressing forming device to melt the hot pressing block and separate and output pure iron and gold-rich iron. A cooling and melting device is connected to the electric arc furnace smelting device to cool and melt gold-rich molten iron, thereby separating gold from iron. A staged condensation device is connected to the fluidized bed thermal storage pre-reduction device and is used to perform staged direct condensation of metal-rich flue gas generated from the fluidized bed thermal storage pre-reduction device and the heating reduction device.

10. The system according to claim 9, characterized in that, It also includes an exhaust gas treatment device, which is connected to the drying and preheating device and the fluidized bed roasting device respectively, to purify the high-temperature flue gas discharged from the drying and preheating device. The solid dust obtained after purification enters the fluidized bed roasting device for fluidized bed roasting to remove cyanide and impurities.

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