A method for producing a niobium carbide powder

Abstract

A preparation method of niobium carbide powder, carbon-containing material, silicon reducing agent, niobium concentrate are sequentially added into a mixing tank, mixed uniformly to obtain mixed raw materials; the mixed raw materials are put into an electric furnace, the electric furnace is heated, the material smelting temperature is gradually maintained, the molten pool temperature reaches 1600 DEG C to 1800 DEG C, after the mixed raw materials are completely melted, the heat preservation reaction is continued for 1 hour, the smelting is finished, the molten slag is poured out, the slag-iron separation is carried out, the carbon-containing niobium-iron alloy is obtained, and the carbon-containing niobium-iron alloy block is crushed; the carbon-containing niobium-iron alloy block is put into a reaction tank, water, inorganic acid, solubilizing agent and oxalic acid are sequentially added as leaching liquid, dissolution leaching is carried out, centrifugal separation is carried out, the solid materials are subjected to multi-stage countercurrent washing, and the niobium carbide powder is obtained. The advantages are: short process flow, low energy consumption, strong operability, easy control of reaction process, high production efficiency, high yield, short production cycle, the obtained niobium carbide product is in powder shape, and high hardness niobium carbide does not need to be crushed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of non-ferrous smelting, and particularly relates to a preparation method of niobium carbide powder. BACKGROUND

[0002] Niobium carbide has high melting point, high hardness, high wear resistance, thermodynamic stability and other performances, and is used for manufacturing parts such as turbine rotor, gas vane, blade, engine nozzle liner and the like. The niobium carbide is expected to become the most ideal strengthening phase in steel materials due to its close density to steel materials. The hard alloy added with niobium carbide can obviously refine grains and significantly improve comprehensive performance, and the cutting tool made of the hard alloy has good thermal hardness, thermal shock resistance and thermal oxidation resistance and the like. In the process of steelmaking, trace amount of niobium carbide is added to achieve the effect of precipitation strengthening and fine grain strengthening, thereby improving the comprehensive mechanical performance of the steel. Therefore, the niobium carbide shows very broad application prospect in the field of steel materials.

[0003] At present, the methods for producing niobium carbide mainly include niobium pentoxide carbon thermal reduction method, metal niobium carbonization method, chemical vapor reaction method and reaction ball milling method. The most commonly used method is the niobium pentoxide carbon thermal reduction method, that is, under high-temperature vacuum condition, niobium pentoxide is carbonized with carbon to obtain niobium carbide product. The process flow is relatively long, the production cycle is long, the production efficiency is low, the energy consumption is high, and the product is still needed to be crushed to obtain niobium carbide powder. The high-hardness niobium carbide is difficult to crush. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a preparation method of niobium carbide powder, which has short process flow, low energy consumption, strong operability, easy control of reaction process, high production efficiency, high yield, short production cycle, and the obtained niobium carbide product is in powder form without the need of crushing high-hardness niobium carbide.

[0005] The technical scheme of the present application is as follows:

[0006] A preparation method of niobium carbide powder, comprising the following steps:

[0007] (1) mixing

[0008] The carbon-containing material, silicon-based reducing agent and niobium concentrate are sequentially added into a mixing tank, the carbon-containing material is graphite, carbon black or coke, the silicon-based reducing agent is industrial silicon, silica or silicon-iron, the weight ratio of the niobium concentrate to the carbon-containing material and the silicon-based reducing agent is 100:(15-25) and 100:(5-15) respectively, and the mixture is uniformly mixed to obtain mixed raw materials;

[0009] (2) electric furnace smelting

[0010] The mixed raw materials are put into an electric furnace, the electric furnace is heated, the temperature of the materials is gradually maintained, the temperature of the molten pool reaches 1600-1800 DEG C, after the mixed raw materials are completely melted, the reaction is continuously maintained for 1 hour, the smelting is finished, the slag is poured out, the slag-iron is separated, and the carbon-containing niobium-iron alloy is obtained;

[0011] (3) crushing

[0012] The carbon-containing niobium-iron alloy is crushed into carbon-containing niobium-iron alloy blocks.

[0013] (4) leaching

[0014] The carbon-containing niobium-iron alloy blocks are put into a reaction tank, water, inorganic acid, a dissolving agent and oxalic acid are sequentially added as leaching liquid for dissolution leaching, the dissolving agent is sodium sulfide and sodium benzoate, the weight ratio of water to the carbon-containing niobium-iron is (3.5-10):1, the mass ratio of oxalic acid to water is 0.1:100-0.3:100, the mass ratio of the dissolving agent to water is 0.1:100-0.3:100, the mass ratio of inorganic acid to water is 40:100-80:100; the dissolution leaching temperature is 40-70 DEG C, during the dissolution leaching, the water and the inorganic acid are first added and dissolved for 2-4 hours, then the oxalic acid is added and dissolved for 1 hour, finally the oxalic acid is added and dissolved for 0.5 hour, centrifugal separation is performed, the solid is reserved, the solid is subjected to multi-stage countercurrent washing, and the niobium carbide powder is obtained.

[0015] Further, the mass content of carbon in the carbon-containing niobium-iron alloy is greater than or equal to 7%.

[0016] As a further preferred solution, the mass content of carbon in the carbon-containing niobium-iron alloy is 7.1%-7.5%.

[0017] Further, the particle size of the niobium carbide powder is less than or equal to 150 mesh.

[0018] Further, the particle sizes of the carbon-containing material, the silicon-based reducing agent and the niobium concentrate are all 10-60 mm; the particle size of the carbon-containing niobium-iron alloy block obtained by crushing in step (3) is less than or equal to 50 mm.

[0019] Further, the mass ratio of sodium sulfide to sodium benzoate in step (4) is 2:1, and the inorganic acid is concentrated sulfuric acid or concentrated hydrochloric acid.

[0020] Further, stirring is performed during the dissolution leaching, and the stirring speed is 100-200 rpm.

[0021] Further, the mass content of Nb2O5 in the niobium concentrate is 30%-40%.

[0022] Furthermore, the multi-stage countercurrent washing is a two-stage countercurrent washing, in which a 0.1% soda ash solution is added for the first stage of washing, and the water washing adopts the second stage of countercurrent washing; the washing temperature of the two-stage countercurrent washing is 30℃~50℃, the washing water flow rate is 100L / hour~300L / hour, and the washing time is 1 hour~2 hours.

[0023] Furthermore, the filtrate obtained from centrifugation is returned to the system for recycling as leachate.

[0024] This invention smelts niobium concentrate and carbon-containing materials in an electric furnace to obtain a niobium-iron alloy with a carbon content of ≥7%. Directly adding inorganic acids to the carbon-containing niobium-iron alloy cannot completely separate iron from the niobium, resulting in low material solubility and product yield, and the purity of the obtained niobium carbide powder does not meet the expected target. By controlling the order and timing of auxiliary material addition and dissolution parameters, the problems of low material solubility, low iron leaching rate, and low product purity are effectively solved, resulting in a high-purity niobium carbide powder product with a high iron leaching rate. Its beneficial effects are:

[0025] (1) The process flow is short, highly operable, easy to control the reaction process, and has high production efficiency. The smelting yield is over 95%, the material dissolution rate is over 99.5%, and the iron leaching rate is over 99.8%. The obtained niobium carbide product is in powder form, eliminating the need to crush high-hardness niobium carbide and avoiding impurities during the powdering process.

[0026] (2) The dissolution and leaching method can complete the entire preparation process within 10 hours compared with the carbothermic reduction method of niobium pentoxide. The process is short, easy to operate, and the parameters are stable. Compared with the 70-hour production cycle of the carbothermic reduction method of niobium pentoxide, the production cycle is short, the energy consumption is low, the production can be carried out intermittently, the amount of additives is small, and the cost is low. Attached Figure Description

[0027] Figure 1 The process flow diagram of the preparation method of niobium carbide powder provided by the present invention. Detailed Implementation

[0028] Example 1

[0029] 1) The raw materials for mixing are niobium concentrate containing 30wt% Nb2O5, coke and silica. The niobium concentrate, coke and silica are all material blocks with a particle size of 10mm to 60mm. 100kg of niobium concentrate, 15kg of coke (1wt% excess) and 5kg of silica are added to the mixing tank in sequence and mixed evenly to obtain the mixed raw materials.

[0030] 2) Electric furnace smelting

[0031] The mixed raw materials are put into an electric furnace, the electric furnace is heated, the power is gradually increased to make the temperature of the molten pool reach 1600-1650 ℃, after the mixed raw materials are completely melted, the reaction is continued for 1 hour, the carbon-containing niobium-iron alloy and slag are obtained, the slag-iron is poured out, and casting separation is performed, 40.68 kg of carbon-containing niobium-iron alloy is obtained, the carbon-containing niobium-iron alloy is detected, the content of iron is 35.5 wt%, the content of carbon is 7.1 wt%, and the smelting yield is 95%;

[0032] 3) crushing

[0033] The 40.68 kg of carbon-containing niobium-iron is crushed to ≤20 mm carbon-containing niobium-iron alloy blocks by using a mechanical crushing method;

[0034] 4) medium and acid dissolution leaching

[0035] All the carbon-containing niobium-iron alloy blocks crushed in step 3) are put into a reaction tank containing 150 kg of water, 33 L of concentrated sulfuric acid is added to the reaction tank, stirring is started, the speed is controlled to be 100 rpm, after 2 hours of reaction, the leaching material is detected, the content of iron is 1.5 wt%, the contents of aluminum and silicon are both more than 1.0 wt%, the leaching rate of iron is 95%; 100 g of a compound of sodium sulfide and 50 g of sodium benzoate is added to the reaction tank, and the reaction is continued for 1 hour, the content of iron in the product is reduced to 0.06 wt%, the leaching rate of iron reaches 99.8%, and the contents of aluminum and silicon are both more than 1.0 wt%, 150 g of oxalic acid is further added to the reaction tank, and the reaction is continued for 0.5 hours, at this time, the contents of aluminum and silicon in the product are both reduced to 0.05 wt%, and the steam amount is controlled during the whole acid dissolution leaching process, so that the dissolution leaching temperature is maintained at 40 ℃;

[0036] 5) centrifugal separation

[0037] The solid-liquid mixture obtained after the dissolution leaching is subjected to centrifugal separation, the obtained solid substance is carbonized niobium powder with inclusions, and the separated solution is transported to the dissolution leaching process through a pipeline for recycling;

[0038] 6) purification and impurity removal

[0039] The obtained carbonized niobium powder with inclusions is washed and purified by using 25 L of a first-stage 0.1 wt% pure alkali solution, and then subjected to secondary water backwashing, the washing temperature of the two-stage countercurrent washing is 40 ℃, the washing water flow rate is 200 L / hour, and the washing time is 1.5 hours, finally, 40.48 kg of pure carbonized niobium powder with a particle size of 150 mesh and a uniform size is obtained, the material dissolution rate is 99.5%, the content of iron in the product is 0.036 wt% after detection, the leaching rate of iron is 99.8%, the content of carbon is 11.28 wt%, the content of oxygen is 0.21 wt%, the content of aluminum is 0.050 wt%, the content of silicon is 0.043 wt%, the content of tantalum is 0.11 wt%, the content of sulfur is 0.009 wt%, the content of free carbon is 0.10 wt%, the purity is 98.73%, and all indexes meet the customer demand indexes.

[0040] Comparative Example 1

[0041] 1) Mixing to obtain a mixture of 30wt% niobium concentrate, coke and silica, the niobium concentrate, coke and silica all having a particle size of 10mm-60mm; 100kg of niobium concentrate, 15kg of coke (1wt% excess), and 5kg of silica were sequentially added to a mixing tank and mixed evenly to obtain a mixed raw material;

[0042] 2) Electric furnace smelting

[0043] The mixed raw material was placed in an electric furnace, the temperature was raised by applying electricity, and the power was gradually increased to bring the temperature of the molten pool to 1600-1650°C. After the mixed raw material was completely melted, the reaction was continued for 1 hour to obtain carbon-containing niobium-iron alloy and slag. The slag and iron were poured out and separated by casting to obtain 40.68kg of carbon-containing niobium-iron alloy. The carbon-containing niobium-iron alloy was detected to contain 35.5wt% of iron and 7.1wt% of carbon, and the smelting yield was 95%;

[0044] 3) Crushing

[0045] The 40.68kg of carbon-containing niobium-iron alloy was crushed to ≤20mm carbon-containing niobium-iron alloy pieces by mechanical crushing method;

[0046] 4) Medium, acid dissolution leaching

[0047] The crushed carbon-containing niobium-iron alloy pieces of step 3) were placed in a reaction tank containing 150kg of water, 33L of concentrated sulfuric acid was added to the reaction tank, stirring was started at a speed of 100rpm, and the reaction was continued for 2 hours. The leaching material was detected to still contain 1.5wt% of iron and more than 1.0wt% of aluminum and silicon. The iron leaching rate was 95%. In order to improve the iron leaching rate and the dissolution rate of the material, the leaching conditions were maintained and the leaching was continued for 5 hours. The iron content in the product was 1.42wt%, the aluminum and silicon contents were 1.0wt%, the iron leaching rate was 96%, and the leaching was continued for another 5 hours. At this time, the iron content in the product was 1.41wt%, and the aluminum and silicon contents were still 1.0wt%. The product index could not meet the customer's demand index.

[0048] From the parallel test of Example 1 and Comparative Example 1, it can be seen that after adding concentrated sulfuric acid and leaching for 2 hours, the leaching rate of iron can reach 95%. In order to improve the leaching rate of iron and the dissolution rate of the material, the additive oxalic acid and the complex of the dissolving agent sodium sulfide and sodium benzoate are added to the reaction tank, and the leaching rate of iron is obviously improved to 99.8%, and the contents of iron, aluminum and silicon are greatly reduced. In Comparative Example 1, without adding additives and dissolving agents, the leaching rate of iron is slightly improved, and the leaching rate is only 96%. Moreover, prolonging the leaching time has little effect on the removal of iron, aluminum and silicon in the product, and the contents of these elements are still high, which cannot meet the customer's demand index (customer's demand index: iron not more than 0.055%, aluminum and silicon not more than 0.05%).

[0049] Example 2

[0050] 1) Mixing: taking 33wt% Nb2O5 niobium concentrate, coke and silica as raw materials, the niobium concentrate, coke and silica are all in the form of 10mm-60mm size blocks; 100kg of niobium concentrate, 20kg of coke (excess 2wt%) and 10kg of silica are sequentially added into a mixing tank and mixed uniformly to obtain mixed raw materials;

[0051] 2) Electric furnace smelting

[0052] The mixed raw materials are put into an electric furnace, the temperature is raised by electricity, and the power is gradually increased to make the temperature of the molten pool reach 1675℃-1725℃. After the mixed raw materials are completely melted, the reaction is continued for 1 hour to obtain carbon-containing niobium-iron alloy and slag. The slag and iron are poured out and separated by casting to obtain 42.59kg of carbon-containing niobium-iron alloy, which contains 37.5wt% of iron and 7.2wt% of carbon. The smelting yield is 95.3%;

[0053] 3) Crushing

[0054] The 42.59kg of carbon-containing niobium-iron alloy is crushed to ≤40mm carbon-containing niobium-iron alloy blocks by mechanical crushing method;

[0055] 4) Medium, acid dissolution and leaching

[0056] Put the broken carbon-containing ferro-niobium alloy pieces of step 3) into a reaction tank containing 300 kg of water, add 130 L of concentrated hydrochloric acid to the reaction tank, start stirring at a speed of 160 rpm, and react for 3 hours. After detection, the product still contains 1.6 wt% of iron, and the contents of aluminum and silicon are both above 1.0 wt%. The leaching rate of iron is 94%. Add 300 g of a compound of sodium sulfide and 150 g of sodium benzoate to the reaction tank and react for 1 hour. The content of iron in the product is reduced to 0.045 wt%, the leaching rate of iron reaches 99.9%, and the contents of aluminum and silicon are still both above 1.0 wt%. Then add 600 g of oxalic acid to the reaction tank and react for 0.5 hours. At this time, the contents of aluminum and silicon in the product are both below 0.05 wt%. During the whole acid dissolution and leaching process, the amount of steam is controlled to maintain the dissolution and leaching temperature at 55℃.

[0057] 5) Centrifugal separation

[0058] Centrifugal separation of the solid-liquid mixture obtained after dissolution is performed to obtain the impure niobium carbide powder. The separated solution is transported by pipeline to the dissolution and leaching process for recycling.

[0059] 6) Purification and impurity removal

[0060] The obtained impure niobium carbide powder is washed and purified by a first-stage 40 L of 0.1% pure lye solution, and then subjected to a second-stage water backwashing. The washing temperature of the two-stage countercurrent washing is 50℃, the washing water flow rate is 100 L / hour, and the washing time is 1 hour. Finally, 42.46 kg of pure niobium carbide powder with a particle size of 180 mesh and a uniformity of full pass is obtained, the material dissolution rate is 99.7%, the content of iron in the product is 0.018%, the leaching rate of iron is 99.9%, the content of carbon is 11.30 wt%, the content of oxygen is 0.19 wt%, the content of aluminum is 0.039 wt%, the content of silicon is 0.041 wt%, the content of tantalum is 0.11 wt%, the content of sulfur is 0.006 wt%, the content of free carbon is 0.11 wt%, and the purity is 99.1%. All the indexes meet the customer's demand indexes.

[0061] Comparative Example 2

[0062] 1) Mixing: Take 100 kg of niobium concentrate containing 33 wt% of Nb2O5, 20 kg of coke (excess 2 wt%), and 10 kg of silica as raw materials. The particle size of the niobium concentrate, coke, and silica is 10 mm-60 mm. Put the niobium concentrate, coke, and silica into a mixing tank in sequence, mix uniformly, and obtain the mixed raw materials.

[0063] 2) Electric furnace smelting

[0064] Put all the mixed raw materials of step 3) into the electric furnace, heat the electric furnace, gradually increase the power to make the temperature of the molten pool reach 1675℃-1725℃, after the mixed raw materials are completely melted, continue to react for 1 hour, obtain carbon-containing ferrocolumbium alloy and slag, pour out the slag-iron, cast and separate to obtain 42.59 kg of carbon-containing ferrocolumbium alloy, which is detected to contain 37.5wt% of iron and 7.2wt% of carbon, and the smelting yield is 95.3%;

[0065] 3) crushing

[0066] The 42.59 kg of carbon-containing ferrocolumbium is crushed to ≤40 mm carbon-containing ferrocolumbium alloy blocks by using mechanical crushing method;

[0067] 4) medium, acid dissolution leaching method

[0068] Put the carbon-containing ferrocolumbium alloy blocks into a reaction tank containing 300 kg of water, add 130 L of concentrated hydrochloric acid to the reaction tank, start stirring at a speed of 160 rpm, and after 3 hours of reaction, it is detected that the product still contains 1.6wt% of iron, and the contents of aluminum and silicon are all above 1.0wt%. The leaching rate of iron is 94%. In order to improve the leaching rate of iron and the dissolution rate of the material, the leaching conditions are maintained to continue leaching for 5 hours, the content of iron in the product is 1.56wt%, the contents of aluminum and silicon are 1.0wt%, the leaching rate of iron is 96%, and the product index cannot meet the customer's demand index.

[0069] It can be known from the parallel test of example 2 and comparative example 2 that after adding concentrated hydrochloric acid for 2 hours of leaching, the leaching rate of iron can reach 94%. In order to improve the leaching rate of iron and the dissolution rate of the material, the reaction tank is added with an additive oxalic acid and a complex of a solubilizing agent sodium sulfide and sodium benzoate, and the leaching rate of iron is obviously improved to 99.9%, and the contents of iron, aluminum and silicon are all greatly reduced. In comparative example 2, without adding the additive and the solubilizing agent, the leaching rate of iron is slightly improved, and the leaching rate is only 96%, and the extension of the leaching time has almost no removal effect on the contents of iron, aluminum and silicon in the product, and the contents are still very high, and the product index cannot meet the customer's demand index (customer's demand index: iron not more than 0.055%, aluminum and silicon not more than 0.05%).

[0070] Example 3

[0071] 1) mixing Take 40wt% Nb2O5 columbium concentrate, coke and silica as raw materials, and the columbium concentrate, coke and silica are all in the form of 10mm-60mm blocks; 100 kg of columbium concentrate, 25 kg of coke (excess 5wt%) and 15 kg of silica are sequentially added into a mixing tank, and mixed uniformly to obtain mixed raw materials;

[0072] 2) electric furnace smelting

[0073] The whole mixed raw materials of step 3) are put into an electric furnace, the electric furnace is heated, the power is gradually increased to make the temperature of the molten pool reach 1750-1800℃, after the mixed raw materials are completely melted, the reaction is continued for 1 hour, the carbon-containing niobium-iron alloy and slag are obtained, the slag-iron is poured out, and is cast to separate, 54.88 kg of carbon-containing niobium-iron alloy is obtained, the detection shows that the content of iron is 39.0wt%, the content of carbon is 7.5%, and the smelting yield is 95.5%;

[0074] 3) crushing

[0075] The 54.88 kg of carbon-containing niobium-iron is crushed to ≤50 mm carbon-containing niobium-iron alloy blocks by using a mechanical crushing method;

[0076] 4) medium and acid dissolution leaching method

[0077] The carbon-containing niobium-iron alloy blocks are put into a reaction tank containing 550 kg of water, 240 L of concentrated sulfuric acid is added to the reaction tank, stirring is started, the speed is controlled at 200 rpm, after 4 hours of reaction, the product still contains 2.0wt% of iron, the contents of aluminum and silicon are both above 1.2wt%, the leaching rate of iron is 95%, 1100 g of sodium sulfide and 550 g of sodium benzoate compound are added to the reaction tank for 1 hour of reaction, the content of iron in the product is reduced to 0.055wt%, the leaching rate of iron reaches 99.9%, and the contents of aluminum and silicon are still both above 1.2wt%, 1650 g of oxalic acid is further added to the reaction tank for 0.5 hours of reaction, at this time, the contents of aluminum and silicon in the product are both below 0.04wt%, and the steam amount is controlled during the whole acid dissolution leaching process to maintain the dissolution leaching temperature at 70℃;

[0078] 5) centrifugal separation method, the solid-liquid mixture obtained after dissolution is centrifugally separated, the obtained solid substance is the mixed niobium carbide powder, and the separated solution is transported to the dissolution leaching process through a pipeline for recycling;

[0079] 6) purification and impurity removal method, the obtained mixed niobium carbide powder is washed and purified by washing with 60 L of a first-stage washing solution of 0.1wt% pure alkali solution, and then is subjected to second-stage water counter-washing, the washing temperature of the two-stage counter-current washing is 30℃, the washing water flow rate is 300 L / hour, and the washing time is 2 hours, finally, 54.77 kg of pure niobium carbide powder with a particle size of 200 mesh and a uniform size is obtained, the material dissolution rate is 99.8%, the detection shows that the content of iron in the product is 0.011wt%, the leaching rate of iron is 99.97%, the content of carbon is 11.19wt%, the content of oxygen is 0.19wt%, the content of aluminum is 0.038wt%, the content of silicon is 0.031wt%, the content of tantalum is 0.11wt%, the content of sulfur is 0.007wt%, the content of free carbon is 0.09wt%, the purity is 99.3%, and all indexes meet the customer demand indexes.

[0080] Comparative example 3

[0081] 1) Mix to contain 40wt% Nb2O5 niobium concentrate, coke and silica as raw materials, niobium concentrate, coke and silica are all granules with particle size of 10mm-60mm; 100kg of niobium concentrate, 25kg of coke (5wt% excess), 15kg of silica are sequentially added into a mixing tank, mixed uniformly to obtain mixed raw materials;

[0082] 2) Electric furnace smelting

[0083] Put all the mixed raw materials crushed in step 3) into an electric furnace, heat the electric furnace, gradually increase the power to make the temperature of the molten pool reach 1750℃-1800℃, after the mixed raw materials are completely melted, continue to react for 1 hour to obtain carbon-containing niobium-iron alloy and slag, pour out the slag and iron, cast and separate to obtain 54.88kg of carbon-containing niobium-iron alloy, which is detected to contain 39.0wt% of iron and 7.5% of carbon, and the smelting yield is 95.5%;

[0084] 3) Crushing

[0085] The 54.88kg of carbon-containing niobium-iron alloy is crushed to ≤50mm carbon-containing niobium-iron alloy granules by mechanical crushing method;

[0086] 4) Medium, acid dissolution leaching method

[0087] Put the carbon-containing niobium-iron alloy granules into a reaction tank containing 550kg of water, add 240L of concentrated sulfuric acid into the reaction tank, start stirring at a speed of 200rpm, after 4 hours of reaction, the product still contains 2.0wt% of iron, the content of aluminum and silicon is all above 1.2wt%, and the leaching rate of iron is 95%. In order to improve the leaching rate of iron and the dissolution rate of the material, continue to leach for 5 hours, the content of iron in the product is 1.8wt%, the content of aluminum and silicon is 1.2wt%, the leaching rate of iron is 95.4%, and continue to react for another 5 hours, at this time the content of iron in the product is 1.78wt%, the content of aluminum and silicon is still 1.2wt%, and the product index cannot meet the customer's demand index.

[0088] From the parallel test of example 3 and comparative example 3, it can be seen that after adding concentrated sulfuric acid and leaching for 2 hours, the leaching rate of iron can reach 95%, in order to improve the leaching rate of iron and the dissolution rate of the material, add additives oxalic acid, and add solubilizer sodium sulfide and sodium benzoate complex to the reaction tank, the leaching rate of iron is obviously improved to 99.9%, and the content of iron, aluminum and silicon is greatly reduced; while comparative example 3 does not add additives and solubilizers, and continues to leach, the leaching rate of iron is slightly improved, which is only 95.4%, and the extension of leaching time has almost no effect on the removal of iron, aluminum and silicon in the product, and the content of each element is still very high, the product index is not up to standard, and cannot meet the customer's demand index (customer's demand index: iron not more than 0.055%, aluminum and silicon not more than 0.05%).

[0089] The above merely provides the specific embodiments of the present application, but should not be used to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing niobium carbide powder, characterized by comprising the following steps: (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching.

2. The method of claim 1, wherein the niobium carbide powder is prepared by the steps of: (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. ​ 3. The method of claim 2, wherein the niobium carbide powder is prepared by the steps of: (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. ​ 4. The method of claim 1, wherein the niobium carbide powder is prepared by the steps of: (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. ​ 5. The method of claim 1 wherein: (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. ​ 6. The method of claim 1, wherein: the niobium carbide powder is prepared by the steps of: forming a niobium powder; and heating the niobium powder in a carbon-containing atmosphere to form the niobium carbide powder. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching.

7. The method of claim 1 wherein: (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. ​ 8. The method of claim 1 wherein: (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. ​ 9. The method of claim 1 wherein: (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. ​ 10. The method of claim 1 wherein: (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) mixing; (2) smelting in an electric furnace; (3) crushing; (4) leaching. (1) ​

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