A method for producing chromium-nickel alloy by carbothermal reduction-magnetic separation

Abstract

The invention discloses a method for producing chromium-nickel alloy by carbon thermal reduction-magnetic separation, wherein fine chromite powder, fine laterite nickel ore powder, reducing agent and additive are mixed to obtain a mixture, the mixture is pressed into a mass to obtain green balls, the green balls are subjected to reduction roasting to obtain reduced balls, the reduced balls are ground to obtain slag abrasives, and the slag abrasives are magnetically separated to obtain chromium-nickel-iron magnetic separation concentrate and magnetic separation tailings; the additive is a mixture of sodium borate and sodium sulfate, and the mass ratio of sodium borate to sodium sulfate in the additive is 0.26-0.32. This product has many advantages such as high recovery rate of valuable metals, low production cost, environmental friendliness and simple process, and provides a new direction for reducing the production cost of stainless steel raw materials.

Description

Technical Field

[0001] The invention belongs to the field of valuable metal recovery, and in particular relates to a method for producing chromium-nickel alloy by carbon thermal reduction-magnetic separation. Background Art

[0002] Chromium and nickel, as important alloying elements, are widely used in stainless steel production to improve the corrosion resistance, toughness, plasticity, weldability and strength of the product. Ferrochrome and ferronickel are the raw materials for chromium and nickel in stainless steel production, respectively. The main processing processes of chromite include electric furnace method, blast furnace method, melting method, etc. The chromite production process has problems such as high production temperature (~1700℃), high power consumption (2372~4024kW·h / t), low production efficiency, high requirements for chromite particle size, and high production cost. Laterite nickel ore is the main raw material for the production of nickel-iron alloy, providing about 70% of nickel products. The process of producing nickel iron from laterite nickel ore includes rotary kiln drying pre-reduction-electric furnace smelting (RKEF) process, sintering-blast furnace process and rotary kiln granular iron process. RKEF process is the mainstream process for laterite nickel ore smelting, with the advantages of mature process, large production scale, good product quality and high production efficiency. However, the processing temperature of the RKEF process is relatively high (~1600℃), and the power consumption and fuel consumption account for more than 65% of the total cost, which has strong limitations for areas with electricity and fuel shortages. In addition, the economic benefits of this process are limited by the nickel grade of the laterite nickel ore raw material. For every 0.1% decrease in the nickel grade of the laterite nickel ore, the process processing cost will increase by 1-2%. Therefore, for the low-grade laterite nickel ore with the largest reserves, the economic benefits of the RKEF process are greatly reduced. Limited by the current environmental pressure, the laterite nickel ore sintering-blast furnace process still needs to be further improved. The rotary kiln granular iron method is the process with the lowest energy consumption for processing laterite nickel ore. It is divided into solid-state reduction method and semi-molten reduction method. It has the advantages of low smelting conditions and simple process, and has great development prospects. As important raw materials, ferrochrome and ferronickel alloys need to be mixed and melted before smelting in stainless steel production. The production and operation costs of stainless steel raw materials such as ferrochrome and ferronickel account for about 65% of the total stainless steel smelting cost.

[0003] The stainless steel production process is mainly divided into one-step, two-step and three-step processes, of which 70% of stainless steel products are produced by the two-step process, where stainless steel scrap, ferrochrome, ferronickel and other alloys are initially melted in an electric furnace or converter, and then refined in an AOD / VOD furnace to obtain a stainless steel crude product. At present, the production of stainless steel using ferronickel and ferrochrome as raw materials has the disadvantages of high production energy consumption, long process and long smelting cycle. This is mainly due to: (1) the high process and equipment costs, long production cycle and long production process caused by the different production processes of ferrochrome and ferronickel; (2) the high process costs such as power consumption caused by the high smelting temperature of ferrochrome and ferronickel (ferronickel: 1550~1600℃, ferrochrome: ~1700℃); (3) the increase in the operating cost of stainless steel production caused by the reheating of ferronickel / ferrochrome cold alloy. Therefore, the present invention uses a mixed system of laterite nickel ore and chromite as raw materials to directly prepare chromium-nickel-iron alloy as a raw material for stainless steel production using a direct reduction magnetic separation process, which not only avoids the high cost caused by the separate process smelting of stainless steel chromium raw materials and nickel raw materials, but also significantly reduces the production cost in the stainless steel production process, which has important economic and social significance for ensuring the healthy and sustainable development of my country's stainless steel industry. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for producing chromium-nickel alloy by carbon thermal reduction-magnetic separation with simple process, low production cost, high recovery rate of valuable metals, high resource utilization rate and environmental friendliness, in view of the high cost, complicated process and long production cycle caused by the separate production process of nickel and chromium raw materials in the existing stainless steel smelting process. The present invention has the advantages of high quality of chromium-nickel-iron alloy products, low energy consumption, low pollution, simple process, low production cost and high production efficiency.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] The present invention discloses a method for producing chromium-nickel alloy by carbon thermal reduction-magnetic separation, comprising the steps of uniformly mixing chromite ore fine powder, laterite nickel ore fine powder, a reducing agent and an additive to obtain a mixture, pressing the mixture into agglomerates to obtain green balls, reducing and roasting the green balls to obtain reduced balls, grinding the reduced balls to obtain slag abrasives, and magnetically separating the slag abrasives to obtain chromium-nickel-iron magnetic separation concentrate and magnetic separation tailings;

[0007] The additive is a mixture of sodium borate and sodium sulfate, and the mass ratio of sodium borate to sodium sulfate in the additive is 0.26-0.32.

[0008] The present invention innovatively adopts a two-step method of reduction roasting-magnetic separation to simultaneously reduce laterite nickel ore and chromite to prepare chromium-nickel-iron alloy as a nickel-chromium raw material for stainless steel production. One of the key points of the technical solution of the present invention is to directly use a direct reduction process to simultaneously reduce the chromium and nickel components in laterite nickel ore and chromite into chromium-nickel-iron metal particles, and use the magnetism of nickel and iron in the alloy to magnetically separate and recover the chromium-nickel-iron metal particles to obtain chromium-nickel-iron alloy. This can not only avoid the separate process production of chromium alloy and nickel alloy raw materials, but also realize the low-cost production of chromite and laterite nickel ore, greatly reducing the cost of stainless steel smelting.

[0009] Another key point of the present invention is to enhance the selective reduction of chromium-nickel-iron components during the reduction process by combining sodium borate and sodium sulfate mixed additives to improve the nickel and chromium grades in the product, promote the growth and aggregation of metal particle size, and improve the metal recovery rate. The inventors found in the experiment that although high temperature and long-term reduction treatment can form large-sized magnetic chromium-nickel-iron metal particles, it provides a prerequisite for subsequent magnetic separation. However, since both laterite nickel ore and chromite contain relatively high iron components, and the reduction priority of the three during the reduction process is: iron component>nickel component>chromium component. Therefore, the iron grade in the reduced product is extremely high, resulting in low grades and recovery rates of chromium and nickel in the product, reducing the economic value of the product.

[0010] In the process of selecting additives, the inventors tried a large number of additives, such as sodium carbonate, sodium chloride, calcium oxide, sodium sulfate and sodium borate. It was unexpectedly discovered that the combination of sodium sulfate and sodium borate in an appropriate ratio can not only transform the iron component into non-magnetic sulfide during the reduction process to improve the chromium and nickel grades in the product, but also react with the silicate components in laterite nickel ore and chromite to form a low melting point phase, release chromium and nickel components, promote mass transfer and heat transfer reactions, increase the size of metal particles, and provide favorable conditions for subsequent magnetic separation.

[0011] Of course, the mass ratio of sodium borate to sodium sulfate needs to be effectively controlled. If the ratio of m(sodium borate) / m(sodium sulfate) is too high, the selective reduction of chromium and nickel cannot be achieved, which reduces the product quality. If the ratio of m(sodium borate) / m(sodium sulfate) is too low, the nickel component and the chromium component will be sulfided, which will deteriorate the reduction of the two.

[0012] In a preferred embodiment, the particle size of the chromite fine powder and the laterite nickel ore fine powder is 20 to 50 μm.

[0013] Controlling the particle size of chromite fine powder and laterite nickel ore fine powder within the above range can achieve the best reduction effect, the shortest time consumption, the lowest energy consumption and the best economic benefit.

[0014] In a preferred embodiment, the chromite fine powder is obtained by grinding chromite.

[0015] In a preferred embodiment, the laterite nickel ore fine powder is obtained by grinding laterite nickel ore.

[0016] In a preferred embodiment, in the chromite fine powder, the mass fraction of Cr2O3 is 40.1-42.5wt%, and the mass ratio of Cr2O3 / FeO is 2.0-2.19.

[0017] In a preferred embodiment, in the laterite nickel ore fine powder, the mass fraction of iron is 33.35-38.47 wt %, and the mass fraction of nickel is 1.45-1.49 wt %.

[0018] In a preferred embodiment, the amount of the chromite fine powder added is 10-45wt% of the mass of the laterite nickel ore fine powder, preferably 20-35wt%.

[0019] In a preferred embodiment, the reducing agent is selected from at least one of small coke, anthracite, lignite, biochar, and coke powder, preferably small coke.

[0020] In a preferred embodiment, the particle size of the reducing agent is 20 to 50 μm.

[0021] In a preferred embodiment, the amount of the reducing agent added is 18.7-19.4 wt % of the total mass of the chromite fine powder and the laterite nickel ore fine powder, preferably 18.9-19.2 wt %.

[0022] In a preferred embodiment, in the additive, the mass ratio of sodium borate to sodium sulfate is 0.27 to 0.31.

[0023] In a preferred embodiment, the additive is added in an amount of 24.6-34.9wt% of the total mass of the chromite fine powder and the laterite nickel ore fine powder, preferably 27.2-31.1wt%. The inventors have found that by controlling the addition amount of sodium borate and sodium sulfate within the above range, the mixture system can react to form a sufficient liquid phase, increase the size of the metal particles, and provide favorable conditions for subsequent magnetic separation.

[0024] In a preferred embodiment, the particle size of the additive is 20 to 50 μm.

[0025] In the actual operation process, according to the different water contents of the chromite fine powder and the laterite nickel ore fine powder, a small amount of water is added as a binder to make the mixture better for compacting and forming.

[0026] In a preferred embodiment, the mixture is pressed into a mass and dried to obtain green balls.

[0027] In a preferred embodiment, the pressure for compacting the mixture is 10 to 30 MPa.

[0028] The inventors have found that by controlling the pressure of the mixture pressing and molding within the above range, green balls with optimal quality and appropriate porosity can be obtained, which is beneficial to the reduction reaction. However, too high a molding pressure will lead to difficulties in the transmission and diffusion of the reducing gas during the reduction process, which is not conducive to the reduction reaction.

[0029] In a preferred embodiment, the reduction roasting temperature is 1200-1400° C., and the reduction roasting time is 2-4 hours.

[0030] The inventors have found through a large number of experiments that in the process of co-reduction of laterite nickel ore and chromite, the reduction of laterite nickel ore and chromite is not synchronized, chromite is difficult to reduce and the process is complicated, and the reduction effect is greatly affected by the reduction temperature and time. Specifically, when the reduction temperature is lower than 900 ° C and the reduction time is <2h, the reduction effect of laterite nickel ore and chromite is very poor, and the metallization rates of chromium and nickel are only 2% and 70%. When the reduction temperature reaches 1100 ° C and the reduction time is >2h, the metallization rate of nickel can reach 90%, but the metallization rate of chromium is lower than 40%, and the chromium spinel maintains its stable structure, forming only fine chromium-containing metal cracks in the middle of the matrix. When the reduction temperature reaches 1150 ° C, the metallization rate of chromium can reach 70%, the chromium metal cracks increase dramatically and the degree increases, but the grain size is still small. When the reduction temperature exceeds 1200°C and additives (calcium oxide, sodium carbonate, sodium borate) are present, the metallization rate of chromium exceeds 90%, the metallization rate of nickel and iron exceeds 90%, and a larger magnetic chromium-nickel-iron alloy is formed, and a clear dividing line is formed between the alloy particles and other silicate impurity components, which is conducive to the separation and recovery of magnetic alloys and non-magnetic impurity products in subsequent ball milling and magnetic separation processes. However, it is worth noting that although the metal reduction in the mixed system of laterite nickel ore and chromite is more thorough and the metal size is more considerable under high temperature conditions, the iron content in the mixed system is higher and its reduction is easiest, resulting in a higher iron grade in the formed chromium-nickel-iron alloy, while the grades of chromium and nickel are lower, reducing the economic value of the alloy. When sodium sulfate and sodium borate are used in combination and the reduction temperature is controlled within the range of 1200-1400°C, the iron component can be converted into non-magnetic sulfide during the reduction process to increase the chromium and nickel grades in the product. It can also react with the silicate components in laterite nickel ore and chromite to form a low-melting point phase, releasing chromium and nickel components, reducing the iron grade in the metal alloy, increasing the chromium and nickel metal grades, and improving the economic value of the alloy product.

[0031] Further preferably, the reduction roasting temperature is 1250-1350° C., and the reduction roasting time is 2.5-4 h.

[0032] In a preferred embodiment, the reduction roasting is carried out under a protective atmosphere, and the flow rate of the protective atmosphere is 0.2 to 0.6 L / min, preferably 0.3 to 0.4 L / min.

[0033] The inventors found that when the flow rate of the protective atmosphere is controlled within the above range, the ultimate microwave pre-reduction effect is optimal. If the flow rate is too low, there is a risk of the newly generated reduction product being oxidized again. If the flow rate of the protective atmosphere is too large, it will not only cause waste, but also take away too much heat, deteriorate the reduction environment, and be unfavorable to the reaction.

[0034] Further preferably, the protective atmosphere is nitrogen.

[0035] In a preferred embodiment, the ball milling is wet ball milling, the ball milling medium is water, the ball milling time is 23 to 40 minutes, preferably 28 to 40 minutes, and the liquid-to-solid mass ratio is controlled to be 0.5 to 1.5, preferably 1 to 1.3 during ball milling.

[0036] In a preferred embodiment, the intensity of the magnetic separation is 900 to 1300 Gs, preferably 1100 to 1200 Gs.

[0037] When the magnetic separation intensity is controlled within the above range, the magnetic separation effect will be optimal. If the magnetic separation intensity is too low, the magnetic separation will be incomplete. If the magnetic separation intensity is too high, it will cause serious impurity inclusions and reduce the quality of the magnetic separation products.

[0038] Principles and advantages of the present invention:

[0039] The innovation of the present invention lies in the use of a two-step method of reduction roasting-magnetic separation to simultaneously reduce laterite nickel ore and chromite to prepare high-quality chromium-nickel-iron alloy as a nickel-chromium raw material for stainless steel production. The main technical key point of the present invention is to use additives in combination and optimize the ratio during the reduction process to achieve the synchronous reduction of laterite nickel ore and chromite and the selective reduction and growth of chromium and nickel components, forming chromium-nickel-iron metal particles, increasing the size of metal particles, and improving the chromium and nickel grades in the product. The chromium-nickel-iron metal particles are magnetically separated and recovered to obtain high-quality chromium-nickel alloy by utilizing the magnetism of nickel and iron in the alloy, which not only avoids the separate process production of chromium alloy and nickel alloy raw materials, but also realizes the low-cost recovery of chromite and laterite nickel ore, greatly reducing the cost of stainless steel smelting. DETAILED DESCRIPTION

[0040] The present invention is further described in detail below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present utility model, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present utility model.

[0041] To avoid repetition, the raw materials involved in this specific implementation are described as follows, and will not be repeated in the specific examples:

[0042] In the chromite fine powder used in the implementation, the mass fraction of Cr2O3 is 40.1-42.5wt%, the mass ratio of Cr2O3 / FeO is 2.0-2.19wt%, and the mass fraction of iron in the laterite nickel ore fine powder used is 33.35-38.47wt%, and the mass fraction of nickel is 1.45-1.49wt%.

[0043] Example 1

[0044] The ground chromite ore, laterite nickel ore, reducing agent and additive powder are mixed evenly in proportion to obtain a mixture, the mixture is pressed into a mass and dried to obtain green balls, the green balls are placed in a tube furnace for reduction roasting to obtain reduction roasting products, the obtained reduction roasting products are placed in a ball mill for grinding to obtain slag abrasives, the slag abrasives are placed in a magnetic separation tube for magnetic separation to obtain chromium-nickel-iron concentrate and magnetic separation tailings.

[0045] The particle size of the laterite nickel ore, chromite, additive and reducing agent fine powder particles is 20 to 50 μm;

[0046] The chromite addition amount is 10wt%;

[0047] The total addition amount of sodium borate and sodium sulfate is 34.9wt%;

[0048] The m(sodium borate) / m(sodium sulfate)=0.26;

[0049] The reducing agent is biochar, and the addition amount is 18.7wt%;

[0050] The green ball forming pressure is 10MPa;

[0051] The reduction temperature is 1200°C and the reduction time is 2h;

[0052] The protective atmosphere is N2, and the gas flow rate is 0.2L / min;

[0053] The ball milling time is 23 min, and the liquid-to-solid ratio is 0.5;

[0054] The magnetic separation intensity of the magnetic separator is 900 Gs.

[0055] The metallization rates of chromium and nickel in the reduction product of Example 1 were 72.1% and 90.1%, respectively, and the metal recovery rates of chromium and nickel in the magnetic separation concentrate were 60.4% and 87.5%, respectively.

[0056] Example 2

[0057] The ground chromite ore, laterite nickel ore, reducing agent and additive powder are mixed evenly in proportion to obtain a mixture, the mixture is pressed into a mass and dried to obtain green balls, the green balls are placed in a tube furnace for reduction roasting to obtain reduction roasting products, the obtained reduction roasting products are placed in a ball mill for grinding to obtain slag abrasives, the slag abrasives are placed in a magnetic separation tube for magnetic separation to obtain chromium-nickel-iron concentrate and magnetic separation tailings.

[0058] The particle size of the laterite nickel ore, chromite, additive and reducing agent fine powder particles is 20 to 50 μm;

[0059] The chromite addition amount is 20wt%;

[0060] The total addition amount of sodium borate and sodium sulfate is 31.1wt%;

[0061] The m(sodium borate) / m(sodium sulfate)=0.27;

[0062] The reducing agent is lignite, and the addition amount is 18.9wt%;

[0063] The green ball forming pressure is 15MPa;

[0064] The reduction temperature is 1250°C and the reduction time is 2.5h;

[0065] The protective atmosphere is N2, and the gas flow rate is 0.3L / min;

[0066] The ball milling time is 27 min, and the liquid-to-solid ratio is 0.8;

[0067] The magnetic separation intensity of the magnetic separator is 1000 Gs.

[0068] The metallization rates of chromium and nickel in the reduction product of Example 2 were 83.4% and 93.4% respectively, and the metal recovery rates of chromium and nickel in the magnetic separation concentrate were 76.4% and 90.5% respectively.

[0069] Example 3

[0070] The ground chromite ore, laterite nickel ore, reducing agent and additive powder are mixed evenly in proportion to obtain a mixture, the mixture is pressed into a mass and dried to obtain green balls, the green balls are placed in a tube furnace for reduction roasting to obtain reduction roasting products, the obtained reduction roasting products are placed in a ball mill for grinding to obtain slag abrasives, the slag abrasives are placed in a magnetic separation tube for magnetic separation to obtain chromium-nickel-iron concentrate and magnetic separation tailings.

[0071] The particle size of the laterite nickel ore, chromite, additive and reducing agent fine powder particles is 20 to 50 μm;

[0072] The chromite addition amount is 30wt%;

[0073] The total amount of sodium borate and sodium sulfate added is 28.6wt%;

[0074] The m(sodium borate) / m(sodium sulfate)=0.30;

[0075] The reducing agent is anthracite, and the addition amount is 19.1wt%;

[0076] The green ball forming pressure is 20MPa;

[0077] The reduction temperature is 1300°C and the reduction time is 3h;

[0078] The protective atmosphere is N2, and the gas flow rate is 0.3L / min;

[0079] The ball milling time is 31 min, and the liquid-to-solid ratio is 1.0;

[0080] The magnetic separation intensity of the magnetic separator is 1100 Gs.

[0081] The metallization rates of chromium and nickel in the reduction product of Example 3 were 90.8% and 94.8% respectively, and the metal recovery rates of chromium and nickel in the magnetic separation concentrate were 87.3% and 92.4% respectively.

[0082] Example 4

[0083] The ground chromite ore, laterite nickel ore, reducing agent and additive powder are mixed evenly in proportion to obtain a mixture, the mixture is pressed into a mass and dried to obtain green balls, the green balls are placed in a tube furnace for reduction roasting to obtain reduction roasting products, the obtained reduction roasting products are placed in a ball mill for grinding to obtain slag abrasives, the slag abrasives are placed in a magnetic separation tube for magnetic separation to obtain chromium-nickel-iron concentrate and magnetic separation tailings.

[0084] The particle size of the laterite nickel ore, chromite, additive and reducing agent fine powder particles is 20 to 50 μm;

[0085] The chromite addition amount is 35wt%;

[0086] The total addition amount of sodium borate and sodium sulfate is 27.2wt%;

[0087] The m(sodium borate) / m(sodium sulfate)=0.31;

[0088] The reducing agent is anthracite, and the addition amount is 19.2wt%;

[0089] The green ball forming pressure is 25MPa;

[0090] The reduction temperature is 1350°C and the reduction time is 3.5h;

[0091] The protective atmosphere is N2, and the gas flow rate is 0.4L / min;

[0092] The ball milling time is 35 min, and the liquid-to-solid ratio is 1.2;

[0093] The magnetic separation intensity of the magnetic separator is 1200 Gs.

[0094] The metallization rates of chromium and nickel in the reduced product of Example 4 were 98.8% and 95.4%, respectively, and the metal recovery rates of chromium and nickel in the magnetic separation concentrate were 91.3% and 93.0%, respectively.

[0095] Example 5

[0096] The ground chromite ore, laterite nickel ore, reducing agent and additive powder are mixed evenly in proportion to obtain a mixture, the mixture is pressed into a mass and dried to obtain green balls, the green balls are placed in a tube furnace for reduction roasting to obtain reduction roasting products, the obtained reduction roasting products are placed in a ball mill for grinding to obtain slag abrasives, the slag abrasives are placed in a magnetic separation tube for magnetic separation to obtain chromium-nickel-iron concentrate and magnetic separation tailings.

[0097] The particle size of the laterite nickel ore, chromite, additive and reducing agent fine powder particles is 20 to 50 μm;

[0098] The chromite addition amount is 45wt%;

[0099] The total addition amount of sodium borate and sodium sulfate is 24.6wt%;

[0100] The m(sodium borate) / m(sodium sulfate)=0.32;

[0101] The reducing agent is anthracite, and the addition amount is 19.4wt%;

[0102] The green ball forming pressure is 30MPa;

[0103] The reduction temperature is 1400°C and the reduction time is 4h;

[0104] The protective atmosphere is N2, and the gas flow rate is 0.6L / min;

[0105] The ball milling time is 40 min, and the liquid-to-solid ratio is 1.3;

[0106] The magnetic separation intensity of the magnetic separator is 1200 Gs.

[0107] The metallization rates of chromium and nickel in the reduced product of Example 5 were 94.4% and 95.8%, respectively, and the metal recovery rates of chromium and nickel in the magnetic separation concentrate were 91.1% and 93.3%, respectively.

[0108] Comparative Example 1

[0109] The other conditions were the same as those in Example 1, except that the reduction temperature was 1100°C.

[0110] The metallization rates of chromium and nickel in the reduced product of Comparative Example 1 were 35.2% and 94.2%, respectively, and the metal recovery rates of chromium and nickel in the magnetic separation concentrate were 14.5% and 60.3%, respectively.

[0111] Comparative Example 2

[0112] The other conditions were the same as those in Example 1, except that the reduction temperature was 1500°C.

[0113] The metallization rates of chromium and nickel in the reduction product of Comparative Example 2 were 94.6% and 95.9%, respectively, and the metal recovery rates of chromium and nickel in the magnetic separation concentrate were 91.0% and 93.1%, respectively.

[0114] Comparative Example 3

[0115] The other conditions were the same as those in Example 4, except that m(sodium borate) / m(sodium sulfate)=0.8;

[0116] The metallization rates of chromium and nickel in the reduction product of Comparative Example 3 were 96.3% and 93.2%, respectively, and the metal recovery rates of chromium and nickel in the magnetic separation concentrate were 79.9% and 80.9%, respectively.

[0117] Comparative Example 4

[0118] The other conditions were the same as those in Example 4, except that m(sodium borate) / m(sodium sulfate)=0.05;

[0119] The metallization rates of chromium and nickel in the reduction product of Comparative Example 4 were 83.1% and 85.0%, respectively, and the metal recovery rates of chromium and nickel in the magnetic separation concentrate were 72.1% and 73.2%, respectively.

[0120] Comparative Example 5

[0121] Other conditions were the same as those in Example 4, except that the total addition amount of sodium borate and sodium sulfate was 15.0 wt %;

[0122] The metallization rates of chromium and nickel in the reduced product of Comparative Example 5 were 58.7% and 67.3%, respectively, and the metal recovery rates of chromium and nickel in the magnetic separation concentrate were 56.3% and 59.8%, respectively.

[0123] Comparative Example 6

[0124] Other conditions were the same as those in Example 4, except that the total addition amount of sodium borate and sodium sulfate was 40.0 wt %;

[0125] The metallization rates of chromium and nickel in the reduced product of Comparative Example 6 were 98.2% and 95.6%, respectively, and the metal recovery rates of chromium and nickel in the magnetic separation concentrate were 91.0% and 93.2%, respectively.

[0126] Comparative Example 7

[0127] The other conditions were the same as those in Example 4, except that the additive was CaO, and the addition amount was 27.2 wt%;

[0128] The metallization rates of chromium and nickel in the reduced product of Comparative Example 7 were 92.1% and 88.4% respectively, and the metal recovery rates of chromium and nickel in the magnetic separation concentrate were 75.5% and 76.4% respectively.

[0129] Comparative Example 8

[0130] The other conditions were the same as those in Example 4, except that the additive was sodium carbonate, which was added in an amount of 27.2 wt %;

[0131] The metallization rates of chromium and nickel in the reduced product of Comparative Example 8 were 93.1% and 86.0%, respectively, and the metal recovery rates of chromium and nickel in the magnetic separation concentrate were 78.2% and 79.5%, respectively.

[0132] It is obvious to those skilled in the art that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is limited by the appended claims rather than the above description, and it is therefore intended that all changes within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0133] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for producing chromium-nickel alloy by carbothermal reduction-magnetic separation, characterized in that: The chromite fine powder, the laterite nickel ore fine powder, the reducing agent and the additive are mixed to obtain a mixture, the mixture is pressed into a mass to obtain green balls, the green balls are reduction roasted to obtain reduced balls, the reduced balls are ground to obtain slag abrasives, and the slag abrasives are magnetically separated to obtain chromium-nickel-iron magnetic separation concentrate and magnetic separation tailings; The additive is a mixture of sodium borate and sodium sulfate, and the mass ratio of sodium borate to sodium sulfate in the additive is 0.26-0.

32.

2. The method for producing chromium-nickel alloy by carbothermal reduction-magnetic separation according to claim 1, characterized in that: The particle size of the chromite fine powder and the laterite nickel ore fine powder is 20-50 μm.

3. The method for producing chromium-nickel alloy by carbothermal reduction-magnetic separation according to claim 1 or 2, characterized in that: In the chromite fine powder, the mass fraction of Cr2O3 is 40.1-42.5wt%, and the mass ratio of Cr2O3 / FeO is 2.0-2.19%; In the laterite nickel ore fine powder, the mass fraction of iron is 33.35-38.47 wt%, and the mass fraction of nickel is 1.45-1.49 wt%.

4. The method for producing chromium-nickel alloy by carbothermal reduction-magnetic separation according to claim 1 or 2, characterized in that: The amount of the chromite fine powder added is 10-45 wt% of the mass of the laterite nickel ore fine powder.

5. The method for producing chromium-nickel alloy by carbothermal reduction-magnetic separation according to claim 1 or 2, characterized in that: The reducing agent is selected from at least one of small coke, anthracite, lignite, biochar, and coke powder. The particle size of the reducing agent is 20-50 μm; The amount of the reducing agent added is 18.7-19.4wt% of the total mass of the chromite fine powder and the laterite nickel ore fine powder.

6. The method for producing chromium-nickel alloy by carbothermal reduction-magnetic separation according to claim 1 or 2, characterized in that: In the additive, the mass ratio of sodium borate to sodium sulfate is 0.27-0.31; The additive is added in an amount of 24.6-34.9 wt% of the total mass of the chromite fine powder and the laterite nickel ore fine powder. The particle size of the additive is 20-50 μm.

7. The method for producing chromium-nickel alloy by carbothermal reduction-magnetic separation according to claim 1 or 2, characterized in that: The mixture is pressed into a mass and dried to obtain green balls; the pressure of the mixture pressed into a mass is 10-30 MPa.

8. The method for producing chromium-nickel alloy by carbothermal reduction-magnetic separation according to claim 1 or 2, characterized in that: The reduction roasting temperature is 1250-1350°C, and the reduction roasting time is 2.5-4 h; The reduction roasting is carried out under a protective atmosphere, and the flow rate of the protective atmosphere is 0.2-0.6 L / min.

9. The method for producing chromium-nickel alloy by carbothermal reduction-magnetic separation according to claim 1, characterized in that: The grinding is ball milling, the ball milling adopts wet ball milling, the ball milling medium is water, the ball milling time is 23-40 min, and the liquid-solid mass ratio is controlled to be 0.5-1.5 during ball milling.

10. The method for producing chromium-nickel alloy by carbothermal reduction-magnetic separation according to claim 1 or 9, characterized in that: The intensity of the magnetic separation is 900~1300 Gs.