Beneficiation system for comprehensively recovering gold, silver and iron from limonite type gold oxide ore

Abstract

The utility model relates to a mineral separation system for comprehensively recovering gold, silver and iron from limonite type gold oxide ore, which comprises a ball mill, a discharge port of the ball mill is connected to a feed port of a cyclone A through an ore pulp tank A and a slurry pump, and an overflow port of the cyclone A is sequentially connected to a stirring barrel A, a weak magnetic roughing machine I, a weak magnetic roughing machine II and a weak magnetic classificator; a concentrate outlet of the weak magnetic classificator is connected to the thickener A, an underflow port of the thickener A is connected to the ore pulp tank B, the ore pulp tank B is connected to a feed port of the cyclone B through the slurry pump, a sand settling port of the cyclone B is connected to a feed port of the vertical mill A, a discharge port of the vertical mill A is connected to the ore pulp tank B, and an overflow port of the cyclone B is connected to the stirring barrel B; and a discharge hole of the stirring barrel B is connected to the leaching barrel A. The device achieves comprehensive and efficient recovery of gold, silver and iron, is excellent in silver and iron recovery effect, has great significance in efficient enrichment of limonite type gold oxide ore difficult to separate and utilize, and is worthy of industrial popularization and application.

Description

Technical Field

[0001] This utility model belongs to the field of precious metal metallurgy technology, specifically relating to a mineral processing system for the comprehensive recovery of gold, silver and iron from limonite-type oxidized gold ore. Background Technology

[0002] Gold exhibits both siderophile and chalcophile properties, and in the Earth's crust, it is typically associated with sulfide minerals such as pyrite, arsenopyrite, and chalcopyrite, as well as oxide minerals such as magnetite and limonite. Gold and silver are closely related to iron minerals, with over 50% of gold and silver usually found in limonite. In limonite-type gold deposits, gold mainly exists in isomorphous or adsorbed forms within limonite and gangue minerals. The gold is generally found as single gold particles, fractured gold, or encapsulated gold, with a low gold grade, typically less than 2 g / t. The iron grade in the oxide ore is also low, usually <35%. The main metallic minerals are iron oxide minerals such as limonite, magnetite, and hematite, while the gangue minerals are primarily carbonate minerals such as dolomite and calcite, followed by clay minerals such as chlorite, kaolinite, and sericite.

[0003] Limonite-type gold oxide ore is a difficult-to-process and difficult-to-utilize associated iron ore resource, and its comprehensive recovery and utilization has always been a major challenge in the mineral processing field. The existing recovery process, "fine grinding of raw ore—cyanidation leaching of gold and silver in whole mud—magnetic separation of iron," prioritizes gold and silver recovery with iron recovery as a secondary objective, resulting in the ineffective recovery of a large amount of iron resources. To ensure the leaching of gold and silver, the raw ore typically needs to be finely ground to a particle size of -325 mesh or higher (over 85%) to fully expose and dissociate the gold inclusions. While this process can improve the leaching rates of gold and silver to some extent, fine grinding leads to over-grinding and mudification of clay minerals and coarse-grained associated iron minerals, especially limonite. This results in low activated carbon adsorption and desorption rates, large amounts of cyanidation tailings, and difficulties in dewatering concentrates and tailings. Furthermore, during magnetic separation for iron recovery, the low content of easily beneficiated magnetite and the high content of difficult-to-process and difficult-to-utilize limonite in limonite-type gold oxide ore make it difficult for the limonite concentrate to achieve ideal recovery targets. In terms of silver recovery, although silver is also leached when gold is leached, when silver exists in the ore in the form of manganese silver oxide, since natural manganese silver oxide is a colloidal mineral, silver is usually dispersed in manganese oxide minerals in the form of ion adsorption and isomorphism. Silver is difficult to be physically dissociated and exposed to the surface of mineral particles to be enriched or leached, and its comprehensive recovery index is often low.

[0004] For the technical problem of the inefficient recovery and utilization of difficult-to-process and difficult-to-benefit iron ore resources by existing recycling processes, magnetized roasting is considered an effective means to break through the bottleneck of traditional mineral processing technology. Magnetized roasting refers to the technology of converting weakly magnetic iron minerals such as limonite (Fe2O3·nH2O), hematite (Fe2O3), and siderite (FeCO3) into strongly magnetic Fe3O4 through a roasting reaction under certain temperature conditions. However, traditional magnetized roasting shaft furnaces and rotary kilns, due to the use of centimeter-sized lumps (>15mm), have poor gas-solid contact and often require high reaction temperatures (700-800℃) to obtain a fast reaction rate. This results in uneven reduction inside and outside the lumps and low magnetization efficiency. When Fe2O3 on the surface of the lump ore (15-75mm) is reduced to Fe3O4, its interior is not yet reduced; while when the interior is reduced to Fe3O4, the surface has been further over-reduced to weakly magnetic FeO. From a thermodynamic perspective, the reduction temperature in the furnace is generally between 700 and 800°C, which is exactly in the FeO formation zone. Weakly magnetic FeO will directly reduce the total iron recovery rate of subsequent weak magnetic separation. Moreover, vertical shaft furnaces and rotary kilns cannot process fine ore. Due to the defects in their own equipment, over-reduction is difficult to avoid, and the advantages of the magnetization roasting method for difficult-to-select iron ore cannot be fully utilized, ultimately resulting in low total iron recovery, high energy consumption, and poor economic efficiency. Utility Model Content

[0005] Based on existing defects and shortcomings, this utility model provides a highly adaptable, comprehensive, energy-saving, and environmentally friendly beneficiation and smelting method and system for the efficient and comprehensive recovery of gold, silver, and iron from limonite-type oxidized gold ore. This method first, based on the mineralogical characteristics and magnetic features of limonite-type oxidized gold ore, after coarse grinding of the raw ore, uses magnetic separation to target and enrich gold-silver magnetite concentrate, gold-silver limonite / manganese-silver oxide ore, and non-magnetic products. Then, based on the mineralogical characteristics of gold, silver, and iron in the three products, such as their occurrence state, intercalation relationship, and particle size characteristics, a recovery process tailored to the ore properties of each enriched product is formulated. The process parameters for recovering valuable metals from the above products are precisely controlled. While achieving comprehensive and efficient recovery of precious metals like gold and silver, this method also enhances the efficient enrichment of difficult-to-benefit and difficult-to-utilize limonite resources through energy-saving technology, producing high-value-added magnetite concentrate.

[0006] To achieve the above objectives, this utility model provides a beneficiation method for the comprehensive recovery of gold, silver, and iron from limonite-type oxide gold ore, comprising the following steps:

[0007] (1) Targeted enrichment of raw ore by coarse grinding and magnetic separation: The raw ore is coarsely ground and classified, with a coarse grinding particle size of -200 mesh accounting for 60% to 75%; the overflow of the classification is subjected to weak magnetic coarsening I to obtain iron rough concentrate I and tailings I; tailings I is subjected to weak magnetic coarsening II to obtain iron rough concentrate II and tailings II; iron rough concentrate I and iron rough concentrate II are subjected to weak magnetic cleaning to obtain strong magnetic products (i.e., gold and silver magnetite concentrate) and weak magnetic cleaning tailings (mainly fine-grained magnetite or its intergrowths); tailings II is subjected to strong magnetic coarsening I to obtain strong magnetic rough concentrate I and tailings III; tailings III is subjected to strong magnetic coarsening II to obtain strong magnetic rough concentrate II and non-magnetic products; weak magnetic cleaning tailings, strong magnetic rough concentrate I and strong magnetic rough concentrate II are combined into weak magnetic products (i.e., gold and silver limonite and manganese silver oxide ore).

[0008] This process involves coarse grinding of the raw ore, followed by two coarse and one fine weak magnetic separations and two strong magnetic coarse separations to target and enrich minerals with different magnetic properties. This avoids the problem of magnetite and limonite being over-grinded and unable to be effectively collected due to traditional fine grinding. It also solves the problem of producing a large amount of secondary slime due to fine grinding of easily mud-forming metal minerals such as limonite and clay gangue such as chlorite, kaolin, and sericite, which worsens the subsequent process parameters such as gold and silver cyanide leaching, activated carbon adsorption, and magnetic separation.

[0009] For fine-grained magnetite, the specific magnetic susceptibility decreases with decreasing particle size, while the coercivity increases accordingly, making separation increasingly difficult as the particle size decreases. Therefore, the weak magnetic coarsening stage employs a permanent magnet separator with medium-to-high field strength, low magnetic separation gap, and a certain magnetic field gradient to enhance separation, effectively increasing the specific magnetic force f experienced by strongly magnetic mineral particles. m , make f m The resultant force ∑F of all mechanical forces acting on the particle in the opposite direction to the magnetic force is greater than the resultant force ∑F. 机 This effectively recovers fine-grained magnetite particles. For limonite (-0.02mm) that has become muddy during grinding, the second stage of strong magnetic roughing uses a high gradient (increasing the specific magnetic force f). m High stroke (beneficial for loose mineral particles) and low stroke (reducing the inertial force of mineral particles) enhance the dispersion and separation of mineral particles in the slurry, further strengthening the comprehensive recovery of fine and micro-fine-grained limonite. In this way, the magnetic differences among the three products can be utilized to achieve sufficient enrichment and separation, facilitating the implementation of subsequent targeted measures and improving the overall resource recovery index.

[0010] (2) Fine grinding and cyanide leaching of strong magnetic products: The strong magnetic products obtained in step (1) are concentrated and refmilled. The fineness of the refmilling is -0.045 mm, accounting for 70% to 85%. Lime milk is added to adjust the slurry to pH≈11. Then sodium cyanide solution is added and aerated and stirred for leaching. After leaching for 32 to 42 hours, activated carbon is added for gold and silver adsorption to obtain gold-loaded carbon I and leaching residue I. Leaching residue I is magnetite concentrate I.

[0011] (3) Low-temperature fluidized magnetization roasting of weak magnetic products: The weak magnetic products obtained in step (1) are concentrated and filtered. The filtered products are then transported to a fluidized bed for roasting. During roasting, reducing industrial coal gas or reforming reducing gas containing CO and H2 is continuously introduced from the bottom of the fluidized bed, so that the powdered ore particles in the fluidized bed achieve a stable fluidized state under the action of the bottom airflow. The powdered ore is then subjected to low-temperature fluidized magnetization roasting. The weak magnetic iron-containing minerals undergo an efficient gas-solid reaction with the reducing gas to produce strongly magnetic roasted ore.

[0012] This process employs a magnetized roasting technique. Under specific temperature and atmosphere conditions, the weakly magnetic limonite (Fe2O3·nH2O) is converted into strongly magnetic Fe3O4 through a roasting reaction. Then, conventional weak magnetic separation effectively separates the magnetic iron from the gangue minerals, yielding a high-quality magnetite concentrate product. The principle is as follows:

[0013] When the magnetization roasting of limonite is below 400℃, a dehydration reaction (1) occurs first. Under the conditions of reduction atmosphere (CO+H2), it is directly reduced and a magnetization roasting reaction (2) occurs to complete the magnetic conversion.

[0014] Fe2O3·nH2O(s)→Fe2O3(g)+nH2O(g) (1)

[0015] 3Fe2O3(s)+H2 / CO(g)→2Fe3O4(s)+H2O / CO2(g) (2)

[0016] The reducing potential of the reducing gas in industrial magnetized roasting (CO+H2) / (CO+H2+CO2+H2O) is mostly between 0.3 and 0.6. Figure 3 According to the thermodynamic phase diagram of iron oxide reduction, when the reduction temperature is higher than 570℃ and the reduction potential R value (CO+H2) / (CO+H2+CO2+H2O) of industrial gas (blast furnace, converter and coke oven gas) is mostly between 0.3 and 0.6, during the phase transformation of weakly magnetic iron minerals, strongly magnetic magnetite Fe3O4 will be further reduced to weakly magnetic flostenite FeO, that is, an "over-reduction reaction" (3) will occur, and FeO will directly reduce the subsequent weak magnetic separation total iron recovery rate.

[0017] This reaction is reversible. To prevent the formation of flostenite, magnetization calcination can be carried out under conditions of high temperature and low reduction potential (R value) above 570 ℃, or low temperature and high reduction potential below 570 ℃.

[0018] Fe3O4+H2 / CO→3FeO+H2O / CO2 (3)

[0019] Therefore, it can be seen that weakly magnetic products—limonite rough concentrate—can be fully transformed into strongly magnetic magnetite through fluidized bed magnetization roasting, under scientifically controlled roasting temperature and industrial gas reduction potential. This fundamentally changes the phase properties and solves the shortcomings of traditional vertical shaft furnace and rotary kiln magnetization roasting, such as high energy consumption, uneven reduction inside and outside the ore particles, low magnetization efficiency, and inability to process fine ore. Figure 3 Choosing low-temperature fluidized bed magnetization roasting at temperatures of 450–550℃ and an industrial gas reduction potential R of 0.4–0.6 allows for complete reduction and magnetic transformation of limonite, preventing over-reduction and the formation of weakly magnetic FeO. This approach offers significant advantages such as high total iron yield, low energy consumption, and excellent economic efficiency. Furthermore, because the fluidized bed uses whole-powder ore (<3mm) for roasting, the heat and mass transfer efficiency of the fluidized bed reaction is extremely high. Under these conditions, the magnetization roasting reaction can be completed in minutes, a time significantly shorter than the hourly process for centimeter-sized lumps in vertical shaft furnaces and rotary kilns.

[0020] During fluidized bed magnetization roasting, the gold-silver-bearing limonite and manganese-silver ore particles undergo thermal decomposition and develop pores. The microstructure of the roasted ore is loose and porous, which can increase the solid-liquid reaction contact area in the subsequent leaching process, open the liquid passage for leaching gold and silver with cyanide solution, improve the cyanide leaching reaction kinetics, and accelerate the diffusion rate of the leaching solution and the cyanide leaching reaction.

[0021] (4) Roasted ore cyanide leaching: After the roasted ore obtained in step (3) is cooled, lime milk is added to adjust the slurry to pH≈11, and then sodium cyanide is added and stirred for leaching. After leaching for 32-42 hours, activated carbon is added for gold and silver adsorption to obtain gold-loaded carbon II and leaching residue II.

[0022] (5) Two-stage weak magnetic separation of leaching residue II: The leaching residue II is subjected to a first-stage weak magnetic separation to obtain a first-stage weak magnetic separation concentrate and tailings; the first-stage weak magnetic separation concentrate is regrinded to a concentration of -0.045mm or more than 70%, and then subjected to a second-stage weak magnetic separation to obtain magnetite concentrate II and tailings.

[0023] By regrinding the first-stage weak magnetic separation concentrate, the magnetite is fully liberated from the non-magnetic minerals, thereby improving the grade of the magnetite concentrate produced by the second-stage weak magnetic separation.

[0024] (6) Cyanide leaching of non-magnetic products: Add lime milk to the non-magnetic product obtained in step (1) to adjust the pH to ≈11, then add sodium cyanide and stir to leach. After leaching for 32-42 hours, add activated carbon to adsorb gold and silver to obtain gold-loaded carbon III and leaching residue III.

[0025] Further, in step (1), the magnetic field strength of the weak magnetic coarse selection one is 0.15-0.3T, the sorting gap is 40-60mm, and the working concentration is 25%-35%; the magnetic field strength of the weak magnetic coarse selection two is 0.2-0.4T, the sorting gap is 30-50mm, and the working concentration is 20%-30%; the magnetic field strength of the weak magnetic fine selection is 0.12-0.3T, the sorting gap is 25-45mm, and the working concentration is 15%-25%; the background field strength of the strong magnetic coarse selection one is 0.9-1.3T, the rod dielectric wire diameter is 2-5mm, and the working concentration is 15%-25%; the background field strength of the strong magnetic coarse selection two is 1.0-1.5T, the rod dielectric wire diameter is 2-5mm, and the working concentration is 15%-25%.

[0026] Furthermore, in step (2), the concentration of the concentrated underflow is controlled at 25% to 50%; the amount of sodium cyanide added is 2 to 4 kg / t·feed, and the slurry concentration during leaching is controlled at 25% to 40%.

[0027] Furthermore, in step (3), the water content of the filter press product is controlled within 15%; the temperature of low-temperature roasting is controlled at 450-550℃, while the industrial gas reduction potential R is 0.4-0.6, and the roasting time is 2-30 minutes.

[0028] Furthermore, in step (4), the amount of sodium cyanide added is 1 to 3 kg / t of feed, and the slurry concentration is controlled at 25% to 40% during leaching.

[0029] Furthermore, in step (5), the magnetic field strength of the first stage of weak magnetic separation is 0.12 to 0.4 T, and the working concentration is 20% to 35%; the magnetic field strength of the second stage of weak magnetic separation is 0.12 to 0.3 T, and the working concentration is 15% to 35%.

[0030] Furthermore, in step (6), the amount of sodium cyanide added is 2 to 5 kg / t of feed, and the slurry concentration is controlled at 25% to 40% during leaching.

[0031] To achieve the above objectives, this utility model also provides a beneficiation system for the above-mentioned beneficiation method for comprehensive recovery of gold, silver and iron from limonite-type oxide gold ore, including a ball mill. The discharge port of the ball mill is connected to the inlet of hydrocyclone A through a slurry tank A and a slurry pump. The overflow port of hydrocyclone A is sequentially connected to a mixing tank A, a weak magnetic coarse separator I, a weak magnetic coarse separator II, and a weak magnetic fine separator.

[0032] The concentrate outlet of the weak magnetic separator is connected to thickener A. The underflow outlet of thickener A is connected to slurry tank B. Slurry tank B is connected to the feed inlet of hydrocyclone B via a slurry pump. The sand outlet of hydrocyclone B is connected to the feed inlet of vertical mill A. The discharge outlet of vertical mill A is connected to slurry tank B. The overflow outlet of hydrocyclone B is connected to mixing tank B. The discharge outlet of mixing tank B is connected to leaching tank A.

[0033] The tailings outlet of the weak magnetic roughing separator is connected in sequence to the high gradient strong magnetic separator A and the high gradient strong magnetic separator B. The concentrate outlets of the high gradient strong magnetic separator A and the high gradient strong magnetic separator B are connected in sequence to the thickener B, the filter press and the fluidized bed. After passing through the cooler and the roasted ore pile, the fluidized bed is connected to the mixing tank C. The discharge port of the mixing tank C is connected to the leaching tank B. The outlet of the leaching tank B is connected in sequence to the first stage weak magnetic separator, the vertical mill B and the second stage weak magnetic separator.

[0034] The tailings outlet of the high gradient magnetic separator B is connected to the mixing tank D, and the discharge port of the mixing tank D is connected to the leaching tank C.

[0035] Furthermore, the weak magnetic coarse separator I, weak magnetic coarse separator II, weak magnetic fine separator, first-stage weak magnetic separator and second-stage weak magnetic separator are all permanent magnet drum separators.

[0036] Furthermore, leaching tank A, leaching tank B, and leaching tank C are all composed of multiple units connected in series.

[0037] The beneficial effects of this invention are as follows: Based on the mineralogical characteristics and magnetic features of limonite-type oxidized gold ore, this invention, after coarse grinding of the raw ore, uses magnetic separation to target and enrich gold-silver magnetite concentrate, gold-silver limonite / manganese-silver oxide ore, and non-magnetic products. Furthermore, based on the mineralogical characteristics of gold, silver, and iron in these three products, such as their occurrence state, intercalation relationship, and particle size, a recovery process tailored to the properties of each enriched product is formulated. The process parameters for recovering valuable metals from each product are precisely controlled, achieving comprehensive and efficient recovery of gold, silver, and iron. The outstanding performance in silver and iron recovery demonstrates the significant importance of this method for the efficient enrichment of difficult-to-process and utilize limonite-type oxidized gold ore, and it is worthy of widespread application in the industry. Compared with existing technologies, this utility model solves a series of problems caused by low iron and silver recovery rates in limonite and manganese silver oxide ores, over-grinding and mudification of minerals, as well as the problems of high energy consumption, uneven reduction of ore particles, low magnetization efficiency, and inability to process fine ore in traditional vertical shaft furnaces and rotary kilns for magnetization roasting; it has outstanding advantages such as high comprehensive recovery rate, low energy consumption, and economic and environmental protection. Attached Figure Description

[0038] Figure 1 This is a flowchart of a beneficiation method for the comprehensive recovery of gold, silver and iron from limonite-type oxide gold ore according to this utility model;

[0039] Figure 2 This is an equipment diagram of a mineral processing system for the comprehensive recovery of gold, silver and iron from limonite-type oxidized gold ore, according to this utility model.

[0040] Figure 3 It is a thermodynamic phase diagram of iron oxide reduction;

[0041] In the diagram: 1-Ball mill, 2-Slurry tank A, 3-Cyclone A, 4-Agitator A, 5-Weak magnetic coarsener I, 6-Weak magnetic coarsener II, 7-Weak magnetic separator, 8-Thickener A, 9-Slurry tank B, 10-Cyclone B, 11-Vertical mill A, 12-Agitator B, 13-Leaching tank A, 14-High gradient magnetic separator A, 15-High gradient magnetic separator B, 16-Thickener B, 17-Filter press, 18-Fluidized bed, 19-Agitator C, 20-Leaching tank B, 21-First stage weak magnetic separator, 22-Vertical mill B, 23-Second stage weak magnetic separator, 24-Agitator D, 25-Leaching tank C, 26-Cooler. Detailed Implementation

[0042] To make the technical problems and solutions solved by this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present utility model and are not intended to limit the present utility model. Example 1

[0043] Raw Ore #1: A limonite-type oxidized gold ore, with an Au grade of 1.8 g / t, an Ag grade of 18.20 g / t, and a TFe content of 35%. The main metallic minerals are limonite, magnetite, manganese silver oxide, and argentite, etc. The gangue minerals mainly include garnet, diopside, chlorite, epidote, calcite, dolomite, quartz, and kaolinite, etc. The ore structure is mainly composed of granular, anhedral, and colloidal textures. This ore has a low gold grade, predominantly fine-grained native gold. The iron minerals are mainly magnetite / maghemite (iron content approximately 25%–30%) and limonite (iron content >60%), making iron minerals the primary gold-bearing minerals. In the raw ore, gold is present as fine inclusions in magnetic iron (magnetite and maghemite), limonite, and limonite clay, accounting for 18%, 70%, and 4% respectively, with the remainder present in the gangue minerals. Silver is mainly contained in limonite, and is often found in clay filled with limonite pores. Most of it exists in dispersed form in manganese silver oxide minerals, accounting for >80%.

[0044] The existing recovery process of "fine grinding of raw ore - 325 mesh accounting for 85% - cyanide leaching + activated carbon adsorption of gold and silver - weak magnetic separation + strong magnetic separation" is used to recover gold, silver and iron (mainly magnetite / hematite and limonite) from raw ore No. 1. The gold and silver leaching rates are 91% and 31%, respectively; the total iron recovery rate is about 30%, of which the iron grade of magnetite concentrate is 60% and the iron recovery rate is about 20%, and the iron grade of limonite concentrate is 48% and the iron recovery rate is about 10%.

[0045] like Figure 1 As shown, the method described in this utility model is used to recover gold, silver, and iron from raw ore #1. The specific steps are as follows:

[0046] (1) The raw ore was subjected to targeted enrichment by “coarse grinding (-200 mesh accounts for 70%) - two weak magnetic roughing separations + one weak magnetic cleaning separation - two strong magnetic roughing separations”, to obtain a strong magnetic product (containing gold and silver magnetite concentrate) yield of 16% to 18%, with gold and silver grades of approximately 2 g / t and 8.2 g / t, respectively, iron grade >60%, and iron recovery rate ≥30%; a weak magnetic product (containing gold and silver goethite and manganese silver oxide ore) yield of approximately 45%, with gold and silver grades of 2.5 g / t and 25 g / t, respectively, manganese grade of 2.5%, iron grade of approximately 43%, and iron recovery rate of approximately 55%; a non-magnetic product yield of approximately 37% to 39%, with gold and silver grades of 0.89 g / t and 14.67 g / t, respectively, manganese grade of 1.4%, and iron grade of approximately 13.71%;

[0047] (2) The strong magnetic product is concentrated, finely ground (-0.045mm accounts for 80%), cyanide leaching, and activated carbon adsorption to recover precious metals gold and silver. Under the conditions of slurry concentration of 30%, lime slurry adjustment to pH≈11, and sodium cyanide dosage of 3.0 kg / t▪ feed, the leaching is stirred for 36 hours; the leaching residue is magnetite concentrate I with iron grade >60%;

[0048] (3) After the weak magnetic product is concentrated, filtered and dehydrated, it is subjected to fluidized bed magnetic roasting to transform the limonite rough concentrate into magnetite rough concentrate. After cooling, it is subjected to stirring and slurry preparation, cyanide leaching and activated carbon adsorption to recover precious metals gold and silver. Under the conditions of slurry concentration of 34%, lime slurry adjustment to pH≈11 and sodium cyanide dosage of 2.5 kg / t feed, stirring and leaching is carried out for 36 hours. The leaching residue is subjected to stirring and slurry preparation, first stage weak magnetic separation, regrinding (-0.045 mm accounts for 80%) and second stage weak magnetic separation to obtain magnetite concentrate 2 with iron grade >58% and iron recovery rate (to the original ore) of 52.5% and tailings 1.

[0049] (4) Non-magnetic products are concentrated, cyanide leaching and activated carbon adsorption to recover precious metals gold and silver. The leaching residue III is tailings 2.

[0050] The comprehensive mineral processing indicators for this embodiment are detailed in Table 1.

[0051] Table 1: Comprehensive Indicators of Mineral Processing in Example 1

[0052]

[0053] The beneficiation indicators of the existing recovery process compared with those of this invention are as follows: gold leaching rate increased from 91% to 92.09%, silver leaching rate increased from 31% to 50.31%, and total iron recovery rate increased from 30% to 82.5%. Specifically, the iron grade of magnetite concentrate I increased from 60% to 62%, and the iron recovery rate increased from 20% to 30%; the iron grade of limonite concentrate increased from 48% to 58%; and the iron recovery rate of magnetite concentrate II (artificial magnetite) increased from 10% to 52.5%. It can be seen that the method described in this invention achieves higher gold and silver leaching rates and total iron recovery rates for raw ore #1 than the existing recovery processes, especially the significant improvements in silver leaching rate and limonite concentrate-iron recovery rate. Example 2

[0054] Ore #2: A limonite-type oxidized gold ore with an Au grade of approximately 2.0 g / t, associated Ag grade of approximately 47.50 g / t, TFe 39%, and Manganese content of 2.63%. This oxidized ore occurs in the strongly oxidized leaching zone of a primary magnetite-gold deposit. Most of the primary magnetite has been oxidized and leached. The oxidized ore is mainly composed of iron and manganese. Due to the frequent mutual agglomeration of ferric hydroxide gel and manganese hydroxide gel with different charges, limonite and manganese silver oxide are closely associated, but with obvious differences. Limonite and pyrolusite are closely associated and interpenetrated, making it impossible to separate them as independent minerals. The main minerals are iron mineral oxidation and alteration series minerals, including magnetite (hematite) (iron content approximately 14%–18%) and limonite (iron content over 80%), with a relatively deep degree of oxidation. Precious metal minerals include: native gold containing silver, silver-gold ore, spiral silver sulfide, argentite, brittle silver ore, native silver, and tellurite, etc. Gangue minerals are mainly quartz, feldspar, dolomite, calcite and siderite, followed by clay minerals such as kaolinite, chlorite and sericite.

[0055] The occurrence of gold and silver in the ores shows significant differences. Gold mainly exists in the form of free native gold with extremely fine grain size. Free gold accounts for 78.62% of the total gold in the original ore of limonite, native gold accounts for 8.17% of the total gold in the original ore of limonite, gold accounts for 6.10% of the total gold in the original ore of magnetite-maghemite, and gold accounts for only 0.36% of the total gold in the original ore of pyrolusite. The remaining gold is found in clay and gangue. The amount of independent silver minerals (corresponding to exposed silver in phase analysis) in the ore is extremely small, accounting for only 1.48%. Silver in bound state accounts for more than 60% in pyrolusite, silver in bound state accounts for about 10% in limonite, and the remaining silver is found in clay and gangue.

[0056] like Figure 1 As shown, the method of this utility model for recovering gold, silver, and iron from raw ore #2 includes the following specific steps:

[0057] (1) The raw ore was subjected to targeted enrichment by “coarse grinding (-200 mesh accounts for 65%) - two weak magnetic roughing separations + one weak magnetic cleaning separation - two strong magnetic roughing separations”, and the yield of strong magnetic products (containing gold and silver magnetite concentrate) was 8.94%, with iron grade >60% and iron recovery rate of 14% to 18%; the yield of weak magnetic products (containing gold and silver limonite and manganese silver oxide ore) was about 50%, with gold and silver grades of 2.1 g / t and 50 g / t, respectively, manganese grade of about 4.0%, iron grade of about 43%, and iron recovery rate of about 67.5%; the yield of non-magnetic products was about 40%, with iron grade of about 13% to 16%;

[0058] (2) The strong magnetic product is concentrated, regrinded (-0.045mm accounts for 80%), cyanide leaching, and activated carbon adsorption to recover precious metals gold and silver. Under the conditions of slurry concentration of 35%, lime milk adjustment to pH≈10, and sodium cyanide dosage of 3.2kg / t▪ feed, the leaching residue is magnetite concentrate I with iron grade >60%.

[0059] (3) After the weak magnetic product is concentrated, filtered and dehydrated, it is subjected to fluidized bed magnetic roasting. The fluidized bed is used as the reactor for fluidized bed magnetic roasting, and reducing industrial gas is continuously introduced at the bottom of the fluidized bed. The reducing potential R (volume ratio of CO to CO+CO2) of the reducing gas is 40% to 60%. The powder ore is subjected to low temperature fluidized bed magnetic roasting at 450-550℃, and the limonite rough concentrate is transformed into magnetite rough concentrate, producing strong magnetic magnetite. After cooling, the precious metals gold and silver are recovered through stirring and pulping, cyanide leaching, and activated carbon adsorption. Under the conditions of 30% ore pulp concentration, lime slurry adjustment to pH≈11, and sodium cyanide dosage of 2.0 kg / t feed, stirring and leaching is carried out for 36 hours. The leaching residue is then stirred and pulped, followed by a first stage of weak magnetic separation, regrinding (-0.045 mm accounts for 80%), and a second stage of weak magnetic separation to obtain magnetite concentrate II with an iron grade >58% and an iron recovery rate (to the original ore) of 64.2% and tailings 1.

[0060] (4) Non-magnetic products are concentrated, cyanide leaching and activated carbon adsorption to recover precious metals gold and silver. Under the conditions of slurry concentration of 30%, lime milk slurry adjusted to pH≈11 and sodium cyanide dosage of 1.0 kg / t▪ feed, stirring and leaching for 36 h, the leaching residue Ⅲ is tailings 2.

[0061] The comprehensive mineral processing indicators for this embodiment are detailed in Table 2.

[0062] Table 2: Comprehensive Indicators of Mineral Processing in Example 2

[0063]

[0064] As shown in Table 2, the method described in this invention has a good comprehensive recovery effect on gold, silver, and iron in raw ore #2. The gold leaching rate is 90.93%, the silver leaching rate is 60.85%, and the total iron recovery rate is 81%. Specifically, the iron grade of magnetite concentrate I is 60%, and the iron recovery rate is 16.8%, while the iron grade of magnetite concentrate II is 58%, and the iron recovery rate is 64.2%. It is evident that the iron recovery effect in silver and limonite concentrates is particularly outstanding. Example 3

[0065] This embodiment provides a beneficiation system for the comprehensive recovery of gold, silver and iron from limonite-type oxidized gold ore, including a ball mill 1. The discharge port of the ball mill 1 is connected to the feed port of a hydrocyclone A3 through a slurry tank A2 and a slurry pump. The overflow port of the hydrocyclone A3 is sequentially connected to a mixing tank A4, a weak magnetic coarse separator 5, a weak magnetic coarse separator 2, and a weak magnetic fine separator 7.

[0066] The concentrate outlet of the weak magnetic separator 7 is connected to the thickener A 8. The underflow outlet of the thickener A 8 is connected to the slurry tank B9. The slurry tank B9 is connected to the feed inlet of the hydrocyclone B 10 via a slurry pump. The sand outlet of the hydrocyclone B 10 is connected to the feed inlet of the vertical mill A 11. The discharge outlet of the vertical mill A 11 is connected to the slurry tank B 9. The overflow outlet of the hydrocyclone B 10 is connected to the mixing tank B 12. The discharge outlet of the mixing tank B 12 is connected to the leaching tank A 13.

[0067] The tailings outlet of the weak magnetic roughing separator 26 is sequentially connected to the high gradient strong magnetic separator A14 and the high gradient strong magnetic separator B15. The concentrate outlets of the high gradient strong magnetic separator A14 and the high gradient strong magnetic separator B15 are sequentially connected to the thickener B16, the filter press 17 and the fluidized bed 18. The fluidized bed 18 is connected to the mixing tank C19 after passing through the cooler 26 and the roasted ore pile. The discharge port of the mixing tank C19 is connected to the leaching tank B20. The outlet of the leaching tank B20 is sequentially connected to the first stage weak magnetic separator 21, the vertical mill B22 and the second stage weak magnetic separator 23.

[0068] The tailings outlet of the high gradient magnetic separator B 15 is connected to the mixing tank D 24, and the discharge port of the mixing tank D 24 is connected to the leaching tank C 25.

[0069] Among them, the aforementioned weak magnetic coarse separator 1 (5), weak magnetic coarse separator 2 (6), weak magnetic fine separator 7, first-stage weak magnetic separator 21, and second-stage weak magnetic separator 23 are all permanent magnet drum magnetic separators. Leaching tank A (13), leaching tank B (20), and leaching tank C (25) are all composed of multiple units connected in series.

[0070] Working principle: The goethite-type gold oxide ore in the ore powder pile is transported to the ball mill 1 by the conveyor belt for coarse grinding. The coarse grinding is carried out to -200 mesh, accounting for 60% to 75%. The coarsely ground ore is transferred to the slurry tank A2, and then transported to the hydrocyclone A3 for classification by the slurry pump. The overflow ore from the classification enters the mixing tank A4, and the sand ore from the classification enters the ball mill 1 for further grinding. In this way, a closed-loop grinding and classification system is formed.

[0071] After slurry preparation in mixing tank A4, the ore is transferred to a weak magnetic roughing separator 5 for weak magnetic roughing first separation, obtaining iron rough concentrate I and tailings I. Tailings I are then transferred to a weak magnetic roughing separator 6 for weak magnetic roughing second separation, obtaining iron rough concentrate II and tailings II. Iron rough concentrate I and iron rough concentrate II are then transferred to a weak magnetic cleaning separator 7 for weak magnetic cleaning, obtaining a strongly magnetic product (i.e., gold and silver magnetite concentrate) and weakly magnetically cleaned tailings. Tailings II are then transferred to a high-gradient strong magnetic separator A14 for strong magnetic roughing first separation, obtaining strong magnetic rough concentrate I and tailings III. Tailings III are then transferred to a high-gradient strong magnetic separator B15 for strong magnetic roughing second separation, obtaining strong magnetic rough concentrate II and a non-magnetic product. The weakly magnetically cleaned tailings, strong magnetic rough concentrate I, and strong magnetic rough concentrate II are combined into a weakly magnetic product (i.e., gold and silver limonite and manganese silver oxide ore).

[0072] The strong magnetic product obtained by the weak magnetic separator 7 is transferred to the thickener A 8 for concentration. The concentrated underflow is transferred to the slurry tank B 9, and then pumped to the hydrocyclone B 10 for classification. The classified sand is transferred to the vertical mill A 11 for regrinding. The classified overflow is transferred to the mixing tank B, lime milk is added to adjust the slurry, and then transferred to the copper leaching tank A 13. Sodium cyanide is added and aerated for stirring and leaching. After leaching for 32-42 hours, activated carbon is added for gold and silver adsorption to obtain gold-loaded carbon I and leaching residue I. Leaching residue I is magnetite concentrate I.

[0073] The weakly magnetic products obtained from the weak magnetic separator 7, high-gradient strong magnetic separator A 14, and high-gradient strong magnetic separator B 15 are transferred to the thickener B 16 for concentration. The concentrated underflow is then transferred to the filter press 17 for filtration. The filtered product is then transferred to the fluidized bed 18 for low-temperature fluidized magnetic roasting. During roasting, reducing industrial gas is continuously introduced into the bottom of the fluidized bed, causing a highly efficient gas-solid reaction between the weakly magnetic iron-containing minerals and the reducing gas, producing strongly magnetic roasted ore. The roasted ore is then transferred to the cooler 26 and the roasted ore pile for cooling. After the ore is mixed with lime slurry in the stirring tank C 19, it is transferred to the leaching tank B 20, where sodium cyanide is added and the mixture is stirred for leaching. After leaching for 32–42 hours, activated carbon is added for gold and silver adsorption, yielding gold-loaded carbon II and leaching residue II. The leaching residue II is then transferred to a first-stage weak magnetic separator 21 for magnetic separation to obtain a first-stage weak magnetic separator concentrate and tailings. The first-stage weak magnetic separator concentrate is then transferred to a vertical mill B 22 for further grinding until -0.045mm accounts for more than 80%, and then transferred to a second-stage weak magnetic separator 23 for magnetic separation to obtain magnetite concentrate II and tailings.

[0074] The non-magnetic product obtained from the high-gradient magnetic separator B15 is transferred to the mixing tank D24, lime slurry is added to adjust the slurry, and then transferred to the leaching tank C25. Sodium cyanide is added and stirred for leaching. After leaching for 32-42 hours, activated carbon is added for gold and silver adsorption to obtain gold-loaded carbon III and leaching residue III. Leaching residue III is the tailings.

[0075] The present invention has been described in detail above through specific and preferred embodiments. However, those skilled in the art should understand that the present invention is not limited to the embodiments described above. Any modifications or equivalent substitutions made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A mineral processing system for the comprehensive recovery of gold, silver, and iron from limonite-type oxide gold ore, characterized in that, Including a ball mill (1), the outlet of the ball mill (1) is connected to the inlet of a hydrocyclone A (3) via a slurry tank A (2) and a slurry pump. The overflow outlet of the hydrocyclone A (3) is connected in sequence to a mixing tank A (4), a weak magnetic coarse separator one (5), a weak magnetic coarse separator two (6), and a weak magnetic fine separator (7). The concentrate outlet of the weak magnetic separator (7) is connected to the thickener A (8), the underflow outlet of the thickener A (8) is connected to the slurry tank B (9), the slurry tank B (9) is connected to the feed inlet of the hydrocyclone B (10) through the slurry pump, the sand outlet of the hydrocyclone B (10) is connected to the feed inlet of the vertical mill A (11), the discharge outlet of the vertical mill A (11) is connected to the slurry tank B (9), the overflow outlet of the hydrocyclone B (10) is connected to the mixing tank B (12), and the discharge outlet of the mixing tank B (12) is connected to the leaching tank A (13). The tailings outlet of the weak magnetic coarse separator 2 (6) is connected in sequence to the high gradient strong magnetic separator A (14) and the high gradient strong magnetic separator B (15). The concentrate outlets of the high gradient strong magnetic separator A (14) and the high gradient strong magnetic separator B (15) are connected in sequence to the thickener B (16), the filter press (17) and the fluidized bed (18). The fluidized bed (18) is connected to the mixing tank C (19) after passing through the cooler (26) and the roasted ore pile. The outlet of the mixing tank C (19) is connected to the leaching tank B (20). The outlet of the leaching tank B (20) is connected in sequence to the first stage weak magnetic separator (21), the vertical mill B (22) and the second stage weak magnetic separator (23). The tailings outlet of the high gradient magnetic separator B (15) is connected to the mixing tank D (24), and the discharge port of the mixing tank D (24) is connected to the leaching tank C (25).

2. The mineral processing system for the comprehensive recovery of gold, silver, and iron from limonite-type oxide gold ore according to claim 1, characterized in that, The weak magnetic coarse separator one (5), weak magnetic coarse separator two (6), weak magnetic fine separator (7), first-stage weak magnetic separator (21), and second-stage weak magnetic separator (23) are all permanent magnet drum magnetic separators.

3. The mineral processing system for the comprehensive recovery of gold, silver, and iron from limonite-type oxide gold ore according to claim 1, characterized in that, Leaching tank A (13), leaching tank B (20) and leaching tank C (25) are all composed of multiple units connected in series.

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