AU2021448648A1 - Method for producing low nickel matte by smelting, reduction and sulfidation of nickel oxide ore - Google Patents

Abstract

The present disclosure discloses a method for producing low nickel matte by the smelting, reduction and sulfidation of nickel oxide ore. The method mainly comprises: drying and preheating nickel oxide ore to produce hot nickel oxide ore of a temperature of 600 to 900°C; continuously adding the dried and preheated nickel oxide ore and flux into a molten pool of a smelting furnace; spraying a reducing agent, a sulfidizing agent and oxygen-enriched air into a reaction zone of the molten pool in the smelting furnace, and controlling an oxygen excess coefficient α of the oxygen-enriched air to the reducing agent to be 0.3 to 0.4; and controlling the temperature in the furnace to be 1400 to 1550°C, so that the materials added in the furnace undergo a reduction and sulfidation reaction in a molten state to produce low nickel matte and slag. The described method is used for smelting nickel oxide ore, and has the characteristics of good environmental protection, a short process flow, strong adaptability of raw materials, low production costs, etc.

Description

Method for Producing Low Nickel Matte by Smelting, Reduction and Sulfidation of Nickel Oxide Ore

Cross-reference to Related Applications

The present disclosure claims priority to Chinese patent application No. 202110604271.8, entitled "Method for Producing Low Nickel Matte by Smelting, Reduction and Sulfidation of Nickel Oxide Ore", filed with the China Patent Office on May 31, 2021, the entire content of which is incorporated by reference.

Technical Field

The present disclosure relates to the technical field of nickel oxide ore smelting, and particularly, to a one-step method for smelting low nickel matte by smelting, reduction and sulfidation of nickel oxide ore.

Background Art

Nickel is an important strategic metal, has characteristics such as high-temperature resistance, corrosion resistance, and good ductility, and is widely used in the fields such as stainless steel, electroplating, and battery materials. Nickel ore resources are mainly nickel sulfide ore and nickel oxide ore. Nickel sulfide ore contains a greater amount of nickel and is easier to develop and utilize. With the reduction of nickel sulfide ore resources, the development and utilization of nickel oxide ore have become an inevitable trend. The global nickel oxide ore resources account for more than 70% of the total nickel ore resources, and are mainly distributed in the countries near the equator, for example, Indonesia, New Caledonia, Cuba, the Philippines, Brazil, Colombia and Dominica.

The existing processes for treating nickel oxide ore mainly include the wet process and pyrogenic process. The wet process mainly includes ammonia leaching process and acid leaching process. However, the wet process has problems such as poor adaptability of raw materials, high investment, and environmental pollution caused by leaching residues. Therefore, proportion of treatment of nickel oxide ore by wet process is a relatively low.

The pyrogenic process for treatment of nickel oxide ore can be divided into the nickel-iron process and nickel-matte process according to smelted products. The nickel-iron process refers to reduction and smelting of nickel oxide ore to obtain nickel-iron alloy. The nickel-matte process refers to a process of adding a sulfidation agent, and generating matte (sulfonium or sulphonium) and slagging during the production process to obtain an intermediate product, low nickel matte, and then subjecting it to the blowing process to obtain high nickel matte. At present, the pyrogenic process mainly includes the blast furnace smelting process, air furnace smelting process, direct-reduction nodulizing process in a rotary kiln, and a process of rotary furnace pre-reduction-electric furnace melting according to smelting equipment.

The blast furnace smelting process involves dosing and adding agglomerate of nickel oxide ore into a small blast furnace for reduction and smelting to produce slag and nickel-containing pig iron. However, this process has the problems of poor adaptability of raw materials, low nickel grade in ferronickel, high energy consumption, and ease in furnace accretion, etc. Air-furnace matting process for smelting nickel oxide ore involves adding nickel oxide ore, a sulfidation agent, a flux, coke, and the like to the air furnace in batches for smelting, thus producing low nickel matte and slag. However, due to the small air furnace equipment, this process has problems of small processing capacity, poor adaptability of raw materials, serious environmental pollution, requiring a large amount of high-quality coke, and high energy consumption. Direct-reduction nodulizing process in a rotary kiln, also known as Yakin's Oheyama Operation, involves treatment of lateritic ore to produce ferronickel, and has a short process and low energy consumption. However, this process requires harsh operating conditions, the operation is difficult, and the refractory material has short service life. and can realize large-scale production and provide ferronickel products with an excellent quality. However, the electric furnace has high energy consumption and large installation load.

With the rapid growth of the global demand for nickel for battery materials, traditional nickel sulfide ore resources are not able to meet the market demand. The main application of nickel oxide ore is for the stainless steel field, and thus it is imperative to develop and utilize nickel oxide ore to produce intermediate products for battery materials' field.

Summary

The present disclosure aims to solve the technical defects existing in the conventional nickel oxide ore smelting process, and provides a method for producing low nickel matte from nickel oxide ore. The method has the characteristics of being environment-friendly, shorter process, good adaptability of raw materials, low production cost, and the like.

The present disclosure is achieved as follows.

A method for producing low nickel matte by smelting, reduction and sulfidation of nickel oxide ore, the method including:

(1) drying and preheating: drying and preheating nickel oxide ore to produce hot-state nickel oxide ore with a temperature of 600-900°C; and

(2) smelting, reduction and sulfidation: continuously feeding the dried and preheated nickel oxide ore and a flux into a hearth of a smelting furnace; spraying a reducing agent, a sulfidation agent, and oxygen-enriched air into a reaction zone of the hearth in the smelting furnace, with an oxygen excess coefficient a of the oxygen-enriched air relative to the reducing agent being controlled to 0.3-0.4; and controlling a temperature inside the furnace to 1400-1550°C, whereby the materials added in the smelting furnace undergo a reduction and sulfidation reaction in a molten state, producing low nickel matte and slag, wherein the produced low nickel matte contains 15%- 3 0 % nickel and 0. 5 %-3 % cobalt, a recovery rate of nickel metal is 8 8 %-9 6 %, and a recovery rate of cobalt metal is 8 0 %-9 0 %.

In one or more embodiments, step (1) further includes screening the preheated hot-state nickel oxide ore to control a particle size of the hot-state nickel oxide ore fed into the smelting furnace to be less than 50 mm. In the subsequent step, the hot-state nickel oxide ore in a small particle size is added to the hearth of the smelting furnace for reaction, and the small particle size results in rapid melting and high reaction rate.

In one or more embodiments, the reducing agent is coke powder, bituminous coal, or anthracite, greater than 80% of the amount of the reducing agent has a particle size of 200 mesh or more and a mass ratio of the amounts of the nickel oxide ore to the reducing agent added is 100:15-25.

In one or more embodiments, the sulfidation agent may be sulfur, calcium sulfate, nickel sulfide concentrate, pyrite, or the like. The sulfidation agent is, for example, sulfur or calcium sulfate, particularly sulfur. Specifically, calcium sulfate can be obtained by a calcium-based process for flue gas desulfurization, fed back to be used as a flux and sulfidation agent. Sulfur, when used as a sulfdation agent, does not introduce new metal impurities during the smelting process, and not increase the amount of slag produced, as compared with sulfide ores such as nickel sulfide concentrate and pyrite as sulfidation agents, thus avoiding the impact of metal impurities in the sulfidation agent on the low nickel matte product.

In one or more embodiments, the sulfidation agent is sprayed into the smelting furnace in powder form, greater than 80% of the amount of the sulfidation agent has a particle size of 100 mesh or more, for example, 200 mesh or more, and the nickel oxide ore and the sulfidation agent are added in a mass ratio of the nickel oxide ore to sulfur of 100:2-4.

In one or more embodiments, when the sulfidation agent is sulfur, sulfur may also be sprayed into the reaction zone of the hearth in the smelting furnace in liquid form.

In one or more embodiments, high-temperature flue gas generated during the melting, and the reduction and sulfidation reaction is returned to step (1) for drying and preheating the nickel oxide ore, the flue gas is dedusted and then fed into a desulfurization system for desulfurization with calcium oxide or calcium carbonate as a desulfurizing agent, and calcium sulfate produced during the desulfurization process is returned to step (2) to be used as a flux and a sulfdation agent.

In one or more embodiments, the flux is at least one of calcium sulfate and calcium carbonate, and in the smelting, reduction and sulfidation step, the flux is added to give a mass ratio of the nickel oxide ore to the flux of 100:5-15.

In one or more embodiments, in the smelting, reduction and sulfidation step, a volume concentration of oxygen in the oxygen-enriched air sprayed into the reaction zone of the hearth in the smelting furnace is 80-95%, the reducing agent and the sulfidation agent are sprayed into the reaction zone of the hearth through compressed air, and pressures of the oxygen-enriched air and the compressed air for transporting the reducing agent and the sulfidation agent are 0.2 Mpa-0.4 Mpa. In one or more embodiments, the oxygen-enriched air is sprayed into a gas phase space above a liquid level in the furnace for the second time, a volume concentration of oxygen in the oxygen-enriched air sprayed for the second time is 60-80%, and a pressure of the oxygen-enriched air sprayed for the second time is 0.05 Mpa-0.1 Mpa. The spraying of the oxygen-enriched air for the second time aims at burning carbon monoxide (CO) in the gas phase space above the liquid level in the furnace. In one or more embodiments, a metallization rate Meorm of the produced low nickel matte is controlled to be 0.20-0.35, and the metallization rate Meorm of the low nickel matte is expressed by a value obtained by dividing a difference between a theoretical contentStheof sulfur in the low nickel matte and an actual content Sactuai of sulfur in the low nickel matte by the theoretical contentStheooyOf sulfur in the low nickel matte, that is, Meorm = (Stheory - Sactual) Stheory, where Stheory is the theoretical sulfur content when iron, nickel and cobalt in the low nickel matte are completely present in the form of ferrous sulfide (FeS), nickel disulfide (Ni 3 S 2 ), and cobalt sulfide (CoS), respectively, that is, when iron, nickel, and cobalt in the low nickel matte are completely sulfided. In one or more embodiments, the reaction time of smelting, reduction and sulfidation of the materials in the smelting furnace is 1-1.5 hours. In one or more embodiments, the smelting furnace for reduction and sulfidation described above is a hearth-type smelting furnace with a circular vertical structure or a square vertical structure. The present disclosure has the following advantageous effects. The present disclosure overcomes the limitation that nickel oxide ore is difficult to be used in battery materials at present. The process of the present disclosure has high raw material utilization efficiency and easily controllable atmosphere, and is characterized by high sulfidation efficiency, low load of the flue gas desulfurization system, and low cost of flue gas treatment. Therefore, high recovery rates of nickel and cobalt are obtained, and the whole process is stable and environmentally friendly, and is suitable for large-scale industrial production.

Brief Description of Drawings In order to illustrate the technical solutions of the examples of the present disclosure more clearly, the accompanying drawings used in the examples will be briefly introduced below. It should be understood that the following drawings illustrate some examples of the present disclosure, and therefore should be regarded as a limitation of the scope. For those of ordinary skill in the art, other related drawings can also be obtained according to these drawings without any creative effort. FIG. 1 is a schematic flow chart of a method for producing low nickel matte by smelting, reduction and sulfidation of nickel oxide ore in the present disclosure.

Detailed Description of the Embodiments To clarify the objects, technical solutions, and advantages of the examples of the present disclosure, the technical solutions in the examples of the present invention will be described clearly and completely below. If the specific conditions are not indicated in the examples, the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturers. The used reagents or instruments without indication of the manufacturer are conventional products that can be purchased from the market. With reference to FIG. 1, the present disclosure provides a method for producing low nickel matte by smelting, reduction and sulfidation of nickel oxide ore, the method including: (1) drying and preheating: drying and preheating nickel oxide ore to produce hot-state nickel oxide ore with a temperature of 600-900°C; and (2) smelting, reduction and sulfidation: feeding the hot-state nickel oxide ore and a flux into a hearth of a smelting furnace from a furnace top; spraying a reducing agent, a sulfidation agent, and oxygen-enriched air into a reaction zone of the hearth in the furnace through a furnace shaft, with an oxygen excess coefficient a, i.e., an indication of oxygen consumption in the reducing agent in the furnace and the oxygen-enriched air introduced, being controlled to 0.3-0.4; and spraying the oxygen-enriched air into a gas phase space above a liquid level in the furnace for the second time, and controlling a temperature inside the furnace to 1400-1550°C, whereby the materials added in the furnace undergo a reduction and sulfidation reaction in a molten state, producing low nickel matte and slag, wherein a metallization rate Meformof the low nickel matte is controlled to be 0.20-0.35, the produced low nickel matte contains 15%-30% nickel and 0.5%-3% cobalt, a recovery rate of nickel metal is 88%-96%, and a recovery rate of cobalt metal is 80%-90%. According to FIG. 1, the method is mainly divided into two stages: drying and preheating of nickel oxide ore; and smelting, reduction and sulfidation of nickel oxide ore. Drying and preheating of nickel oxide ore The nickel oxide ore are dried and preheated for the main purpose of removal of physical water and crystallization water of the nickel oxide ore and preheating the nickel oxide ore to 600-900°C, so as to provide hot-state materials for the subsequent smelting step and in turn improve the smelting efficiency. A higher material temperature is more advantageous for the subsequent smelting step. However, if the discharge temperature is too high, furnace accretion may be formed in the drying and preheating equipment, which would affect the operation of the equipment. In the drying and preheating process of the nickel oxide ore, high-temperature flue gas produced in the subsequent smelting step is used as a heat source, and pulverized coal combustion is performed for supplementing insufficient heat. The drying and preheating equipment for nickel oxide ore may be a rotary kiln or other equipment, and is not particularly limited herein. The hot-state materials obtained after drying and preheating is screened by a grille, and the undersize is controlled to be less than 50 mm in size, and the specific particle size is not limited. Nickel oxide ore with smaller particle size has a larger specific surface area and a higher reaction rate, which are conducive to complete reaction.

Smelting, reduction and sulfidation of nickel oxide ore

The hot-state nickel oxide ore and flux obtained by the drying and preheating equipment are continuously fed into the smelting furnace from the furnace top, and the reducing agent, the sulfidation agent, and the oxygen-enriched air are sprayed into the reaction zone of the hearth through a furnace shaft. The materials undergo a series of reactions such as reduction and sulfidation in the reaction zone of the hearth to produce low nickel matte and slag. The low nickel matte and slag are separated below the reaction zone in the furnace, the low matte is discharged intermittently, and the slag is continuously discharged for water quenching.

In the smelting process in the present disclosure, the pulverized coal or coke powder is used as fuel and the reducing agent. More than 80% of the amount of the coke powder or pulverized coal (bituminous coal or anthracite) has a particle size of 200 mesh or greater. Here, a mass ratio of the amounts of the nickel oxide ore to the reducing agent added is 100: (15-25). The reducing agent is directly sprayed into the reaction zone of the hearth. In the present disclosure, sulfur or calcium sulfate is used as the sulfidation agent. More than 80% of the amount of sulfur or calcium sulfate has a particle size of 200 mesh or greater. A mass ratio of the amounts of the nickel oxide ore and the sulfidation agent (in terms of mass of sulfur) added is 100: (2-4). The sulfidation agent is directly sprayed into the reaction zone of the hearth. The sulfidation efficiency is high, and the utilization rate of the sulfidation agent can reach % or greater. Namely, 80% or more of the sulfur in the sulfidation agent is present in the low nickel matte product, a small amount is present in the slag, and the remaining is present in the flue gas in the formof S02. Therefore, the subsequent flue gas desulfurization system has a small load, and the flue gas treatment cost is low, which is advantageous for environmental protection.

In the present disclosure, the oxygen-enriched air is used to strengthen smelting. The volume concentration of oxygen in the oxygen-enriched air is 80-95%, and the pressure of the oxygen-enriched air is 0.2-0.4 Mpa. The amount of the oxygen-enriched air sprayed depends on the amount of the raw material to be treated and the amounts of fuel and reducing agent sprayed, and is not limited herein.

In the melting, and the reduction and sulfidation reaction disclosed in the present disclosure, the reaction atmosphere is controlled by adjusting the oxygen excess coefficient, and the oxygen excess coefficient a is 0.3-0.4. The inventors found that an excessively low oxygen excess coefficient would cause more iron to be reduced, resulting in reduced grade of the low nickel matte, and an excessively high oxygen excess coefficient would lead to an increase in the nickel content of the slag, thereby reducing the recovery rate of nickel metal.

The smelting temperature is mainly affected by the slag type. A higher magnesium oxide content of the raw material leads to a higher smelting temperature. In the present disclosure, the temperature of the smelting, reduction and sulfidation process is controlled to be 1400-1550 °C, at which the nickel oxide ore with high magnesium and aluminum contents can be treated, and which is suitable for nickel oxide ores of various slag types. The smelting temperature is adjusted by the amount of pulverized coal or coke powder sprayed, and is not particularly limited herein.

In the present disclosure, the oxygen-enriched air is sprayed into the gas phase space above the melt in the furnace, the volume concentration of oxygen in the oxygen-enriched air is 60-80%, the pressure of the oxygen-enriched air is 0.05 Mpa-0.1 Mpa, and the spraying angle of the oxygen-enriched air is 45°~55° downward from horizontal line. The oxygen-enriched air sprayed into the space is mainly used to burn CO in the flue gas and return the reaction heat back to the hearth.

In the present disclosure, the metallization rate Meform of the low nickel matte is controlled to be 0.20-0.35, and the metallization rate Meorm of the low nickel matte is expressed by a value obtained by dividing a difference between a theoretical content Stheory of sulfur in the low nickel matte and an actual content Sactuai of sulfur in the low nickel matte by the theoretical content Stheooy of sulfur in the low nickel matte, that is, Meform = (Stheory - Sactual)/ Stheory, where Stheory is the theoretical sulfur content when iron, nickel and cobalt in the low nickel matte are completely sulfide, specifically, the theoretical sulfur content after the complete conversion of iron into ferrous sulfide (FeS), the complete conversion of nickel into nickel disulfide (Ni3 S 2 ), and the complete conversion of cobalt into cobalt sulfide (CoS). The inventors found that controlling the metallization rate of the low nickel matte product within a reasonable range can ensure that the obtained product has a higher nickel grade and a higher recovery rate of nickel and cobalt.

Flue gas recycling

The high-temperature flue gas generated during the smelting, reduction and sulfidation reaction is returned to step (1) for drying and preheating the nickel oxide ore through heat exchange. The cooled flue gas is dedusted by a bag-type dust remover and then fed to a desulfurization system for desulfurization. In the desulfurization system, calcium oxide or calcium carbonate is used as the desulfurizing agent to absorb sulfur dioxide in the flue gas, so that the sulfur dioxide content in the flue gas meets the national emission standard. The calcium sulfate produced in the desulfurization process is returned to the smelting, reduction and sulfidation process and used as a flux and a sulfidation agent. The features and performances of the present disclosure will be further described in detail below with reference to specific examples. The nickel oxide ore used in the example contained 1.55% of nickel, 0.07% of cobalt, 16% of iron, 23% of magnesium oxide, and 36% of silicon dioxide. Example 1 The nickel oxide ore was dried and preheated in a rotary kiln to produce hot-state nickel oxide ore with a discharge temperature of 600°C. The hot-state materials produced by drying and preheating was screened by a grille, and the undersize was controlled to be less than 50 mm in size. The hot-state nickel oxide ore and calcium carbonate as a flus were continuously fed to an oxygen-rich hearth-type smelting furnace from the furnace top in a ratio of nickel oxide ore to calcium carbonate of :1. At the same time, pulverized coal as a reducing agent and sulfur as a sulfidation agent were sprayed into a reaction zone of the hearth through the furnace shaft in a ratio of the nickel oxide ore: pulverized coal: sulfur of 100:18:2, and oxygen-enriched air with an oxygen concentration of 85% was sprayed. The pressure of the oxygen-enriched air was 0.2 Mpa, and the oxygen excess coefficient was 0.3. The oxygen-enriched air with an oxygen concentration of 60% was sprayed into a gas phase space above the melt in the furnace at an angle of 45 horizontally downward. The smelting temperature was controlled to be 1500°C. The materials underwent reduction and sulfidation reactions in the reaction zone of the hearth to produce low nickel matte and slag. The low nickel matte contained 27.2% of nickel, 45.62% of iron, 0.99% of cobalt, and 25.2% of sulfur. The recovery rate of nickel metal was 93.5%, the recovery rate of cobalt metal was 85.1%, and the metallization rate of was 0.32. The slag after reduction and sulfidation contained 0.09% of NiO, 17.18% of FeO, 35.87% of SiO 2 , 5.63% of CaO, 22.36% of MgO, and 4.46% of A1 2 0 3 . The low nickel matte was intermittently discharged, and the slag was continuously discharged for water quenching. The smelting flue gas entered the rotary kiln through the flue to dry and preheat the nickel oxide ore. The flue gas discharged through the outlet of the rotary kiln was dedusted by the bag-type dust remover and fed to the desulfurization system, so that the sulfur dioxide content in the flue gas meets the national emission standard. Example 2 This example was implemented using the same parameters as those of Example 1 except that the oxygen excess coefficient was controlled to be 0.35, and is not repeated here. The produced low nickel matte contained 28.1% of nickel, 1.0% of cobalt, 43.59% of iron, and 26.3% of sulfur. The recovery rate of nickel metal was 92.8%, the recovery rate of cobalt metal was 82.6%, and the metallization rate of the low nickel matte was 0.28. The slag after reduction and sulfidation contained 0.12% of NiO, 17.37% of FeO, 35.79% of SiO 2 , 5.62% of CaO, 22.31% of MgO, and 4.45% of A12 0 3 . The fume after reduction and sulfidation was pelletized and then returned for smelting. The low nickel matte was intermittently discharged, and the slag was continuously discharged for water quenching. The smelting flue gas entered the rotary kiln through the flue to dry and preheat the nickel oxide ore. The flue gas discharged through the outlet of the rotary kiln was dedusted by the bag-type dust remover and fed to the desulfurization system, so that the sulfur dioxide content in the flue gas meets the national emission standard.

Example 3

This example was implemented using the same parameters as those of Example 1 except that the oxygen excess coefficient was controlled to be 0.4, and is not repeated here. The produced low nickel matte contained 28.8% of nickel, 1.01% of cobalt, 41.58% of iron, and 27.6% of sulfur. The recovery rate of nickel metal was 91.3%, the recovery rate of cobalt metal was 80.2%, and the metallization rate of the low nickel matte was 0.21. The slag after reduction and sulfidation contained 0.13% of NiO, 17.52% of FeO, 35.73% of SiO 2 , 5.61% of CaO, 22.71% of MgO, and 4.36% of A12 0 3 . The fume after reduction and sulfidation was pelletized and then returned for smelting. The low nickel matte was intermittently discharged, and the slag was continuously discharged for water quenching. The smelting flue gas entered the rotary kiln through the flue to dry and preheat the nickel oxide ore. The flue gas discharged through the outlet of the rotary kiln was dedusted by the bag filter and fed to the desulfurization system, so that the sulfur dioxide content in the flue gas meets the national emission standard.

Example 4

This example was implemented using the same parameters as those of Example 1 except that the amount of the sulfidation agent added was adjusted to give the ratio of the nickel oxide ore: pulverized coal: sulfur added of 100:18:2.5, and is not repeated here. The materials underwent reduction and sulfidation reactions in the reaction zone of the hearth to produce low nickel matte and slag. The low nickel matte contained 26.12% of nickel, 45.66% of iron, 0.97% of cobalt, and 26.30% of sulfur. The recovery rate of nickel metal was 93.81%, the recovery rate of cobalt metal was 85.60%, and the metallization rate of the low nickel matte was 0.272. The slag after reduction and sulfidation contained 0.11% of NiO, 17.08% of FeO, 35.92% of SiO 2 ,

5.64% of CaO, 22.39% of MgO, and 4.46% of A1 2 0 3 . The low nickel matte was intermittently discharged, and the slag was continuously discharged for water quenching. The smelting flue gas entered the rotary kiln through the flue to dry and preheat the nickel oxide ore. The flue gas discharged through the outlet of the rotary kiln was dedusted by the bag-type dust remover and fed to the desulfurization system, so that the sulfur dioxide content in the flue gas meets the national emission standard.

Example 5

This example was implemented using the same parameters as those of Example 1 except that the amount of the sulfidation agent added was adjusted to give the ratio of the nickel oxide ore: pulverized coal: sulfur added of 100:18:3 and the smelting temperature was adjusted to be controlled at 1450°C, and is not repeated here. The materials underwent reduction and sulfidation reactions in the reaction zone of the hearth to produce low nickel matte and slag. The low nickel matte contained 25.34% of nickel, 45.80% of iron, 0.94% of cobalt, and 26.97% of sulfur. The recovery rate of nickel metal was 94.02%, the recovery rate of cobalt metal was 86.43%, and the metallization rate of the low nickel matte was 0.25. The slag after reduction and sulfidation contained 0.11% of NiO, 16.98% of FeO, 35.96% of SiO 2 , 5.65% of CaO, 22.41% of MgO, and 4.67% of A1 2 0 3 . The low nickel matte was intermittently discharged, and the slag was continuously discharged for water quenching. The smelting flue gas entered the rotary kiln through the flue to dry and preheat the nickel oxide ore. The flue gas discharged through the outlet of the rotary kiln was dedusted by the bag-type dust remover and fed to the desulfurization system, so that the sulfur dioxide content in the flue gas meets the national emission standard.

Example 6

This example was implemented using the same parameters as those of Example 5 except that the amount of the sulfidation agent added was adjusted to give the ratio of the nickel oxide ore: pulverized coal: sulfur added of 100:18:3.5, and is not repeated here. The materials underwent reduction and sulfidation reactions in the reaction zone of the hearth to produce low nickel matte and slag. The low nickel matte contained 24.86% of nickel, 45.98% of iron, 0.92% of cobalt, and 27.31% of sulfur. The recovery rate of nickel metal was 94.44%, the recovery rate of cobalt metal was 86.47%, and the metallization rate of the low nickel matte was 0.237. The slag after reduction and sulfidation contained 0.10% of NiO, 16.91% of FeO, 36.00% of SiO 2 5.65% of CaO, 22.44% of MgO, and 4.77% of A1 2 0 3 . The low nickel matte was , intermittently discharged, and the slag was continuously discharged for water quenching. The smelting flue gas entered the rotary kiln through the flue to dry and preheat the nickel oxide ore. The flue gas discharged through the outlet of the rotary kiln was dedusted by the bag-type dust remover and fed to the desulfurization system, so that the sulfur dioxide content in the flue gas meets the national emission standard.

Example 7

This example was implemented using the same parameters as those of Example 5 except that the amount of the sulfidation agent added was adjusted to give the ratio of the nickel oxide ore: pulverized coal: sulfur added of 100:18:4, and is not repeated here. The materials underwent reduction and sulfidation reactions in the reaction zone of the hearth to produce low nickel matte and slag. The low nickel matte contained 23.20% of nickel, 46.92% of iron, 0.86% of cobalt, and 28.12% of sulfur. The recovery rate of nickel metal was 95.14%, the recovery rate of cobalt metal was 87.43%, and the metallization rate of the low nickel matte was 0.213. The slag after reduction and sulfidation contained 0.09% of NiO, 16.64% of FeO, 36.12% of SiO 2 ,

5.67% of CaO, 22.51% of MgO, and 4.49% of A1 2 0 3 . The low nickel matte was intermittently discharged, and the slag was continuously discharged for water quenching. The smelting flue gas entered the rotary kiln through the flue to dry and preheat the nickel oxide ore. The flue gas discharged through the outlet of the rotary kiln was dedusted by the bag-type dust remover and fed to the desulfurization system, so that the sulfur dioxide content in the flue gas meets the national emission standard.

Example 8

This example was implemented using the same parameters as those of Example 1 except that the oxygen excess coefficient was adjusted to 0.1 and the smelting temperature was adjusted to 1550°C, and is not repeated here. The materials underwent reduction and sulfidation reactions in the reaction zone of the hearth to produce low nickel matte and slag. The low nickel matte contained 19.22% of nickel, 55.31% of iron, 0. 7 1% of cobalt, and 23.96% of sulfur. The recovery rate of nickel metal was 95.80%, the recovery rate of cobalt metal was 87.41%, and the metallization rate of the low nickel matte was 0.38. The slag after reduction and sulfidation contained 0.07% of NiO, 15.30% of FeO, 36.70% of SiO 2 , 5.76% of CaO, 22.87% of MgO, and 4.56% of A1 2 0 3 . The low nickel matte was intermittently discharged, and the slag was continuously discharged for water quenching. The smelting flue gas entered the rotary kiln through the flue to dry and preheat the nickel oxide ore. The flue gas discharged through the outlet of the rotary kiln was dedusted by the bag-type dust remover and fed to the desulfurization system, so that the sulfur dioxide content in the flue gas meets the national emission standard. The data of this example shows that an excessively low oxygen excess coefficient would cause a large amount of iron to be reduced, resulting in a reduced grade of low nickel matte.

Example 9

This example was implemented using the same parameters as those of Example 1 except that the oxygen excess coefficient was adjusted to 0.6 and the smelting temperature was adjusted to 1550°C, and is not repeated here. The materials underwent reduction and sulfidation reactions in the reaction zone of the hearth to produce low nickel matte and slag. The low nickel matte contained 20.8% of nickel, 45.61% of iron, 0.52% of cobalt, and 32.13% of sulfur. The recovery rate of nickel metal was 76.80%, the recovery rate of cobalt metal was 47.34%, and the metallization rate of the low nickel matte was 0.05. The slag after reduction and sulfidation contained 0.41% of NiO, 16.94% of FeO, 35.85% of SiO 2 , 5.63% of CaO, 22.35% of MgO, and 4.45% of A12 0 3 . The low nickel matte was intermittently discharged, and the slag was continuously discharged for water quenching. The smelting flue gas entered the rotary kiln through the flue to dry and preheat the nickel oxide ore. The flue gas discharged through the outlet of the rotary kiln was dedusted by the bag-type dust remover and fed to the desulfurization system, so that the sulfur dioxide content in the flue gas meets the national emission standard. The data of this example shows that an excessively high oxygen excess coefficient would cause reduced recovery rates of metals.

Example 10

This example was implemented using the same parameters as those of Example 5 except that the amount of the sulfidation agent added was adjusted to give the ratio of the nickel oxide ore: pulverized coal: sulfur added of 100:18:6 and the smelting temperature was adjusted to be 1500°C, and is not repeated here. The materials underwent reduction and sulfidation reactions in the reaction zone of the hearth to produce low nickel matte and slag. The low nickel matte contained 18.51% of nickel, 46.50% of iron, 0.69% of cobalt, and 33.52% of sulfur. The recovery rate of nickel metal was 95.44%, the recovery rate of cobalt metal was 87.73%, and the metallization rate of the low nickel matte was 0.004. The slag after reduction and sulfidation contained 0.09% of NiO, 15.94% of FeO, 36.49% of SiO 2 , 5.73% of CaO, 22.87% of MgO, and 4.51% of A1 2 0 3 . The low nickel matte was intermittently discharged, and the slag was continuously discharged for water quenching. The smelting flue gas entered the rotary kiln through the flue to dry and preheat the nickel oxide ore. The flue gas discharged through the outlet of the rotary kiln was dedusted by the bag-type dust remover and fed to the desulfurization system, so that the sulfur dioxide content in the flue gas meets the national emission standard. The data of this example shows that an excessively large amount of the sulfidation agent added would result in a reduced grade of low nickel matte.

Example 11

This example was implemented using the same parameters as those of Example 5 except that the amount of the sulfidation agent added was adjusted to give the ratio of the nickel oxide ore: pulverized coal: sulfur added of 100:18:1 and the smelting temperature was adjusted to 1500°C, and is not repeated here. The materials underwent reduction and sulfidation reactions in the reaction zone of the hearth to produce low nickel matte and slag. The low nickel matte contained 28.54% of nickel, 50.02% of iron, 0.97% of cobalt, and 19.44% of sulfur. The recovery rate of nickel metal was 90.10%, the recovery rate of cobalt metal was 76.43%, and the metallization rate of the low nickel matte was 0.51. The slag after reduction and sulfidation contained 0.16% of NiO, 17.14% of FeO, 35.87% of SiO2, 5.63% of CaO, 22.36% of MgO, and 4.45% of A12 0 3 . The low nickel matte was intermittently discharged, and the slag was continuously discharged for water quenching. The smelting flue gas entered the rotary kiln through the flue to dry and preheat the nickel oxide ore. The flue gas discharged through the outlet of the rotary kiln was dedusted by the bag-type dust remover and fed to the desulfurization system, so that the sulfur dioxide content in the flue gas meets the national emission standard. The data of this example shows that the insufficient sulfidation agent would lead to an excessively high metallization rate and affect the recovery rates of metals.

The reaction parameters and product performance data of Examples 1-11 are summarized in Table 1 below.

Table 1 rN rr

00 ccoc oc oc oc oc oc i- oc N o

CD CD CD CD CD CD C ) C

- 00 Cl '0 f

rI) l oCl Cl- Cl ml Cl xl kn r u

Qu

M ClknC O~ Cl- -c - D

0 ~ O ~l ~l ~ ~C C~ ~ ~13f

The above examples and the results thereof show that the parameters such as the oxygen excess coefficient, the amount of the sulfidation agent added, and the smelting temperature all have an impact on the product performance such as the grade, the nickel recovery rate, and the cobalt recovery rate of the produced low nickel matte. In the present disclosure, the above parameters are controlled to be within a reasonable range, which allows the produced low nickel matte to have higher grade and higher recovery rates of nickel and cobalt. The produced low nickel matte contains 15%~30% of nickel and 0.5%~3% of cobalt. The recovery rate of nickel metal is 88%~96%, and the recovery rate of cobalt metal is 80%~90%.The sulfidation efficiency is higher, and the utilization rate of the sulfidation agent can reach 80% or more. The flue gas desulfurization system has a smaller load, and the flue gas treatment cost is lower, which is advantageous for environmental protection.

The above descriptions are only typical examples of the present disclosure, and are not intended to limit the present disclosure. For those skilled in the art, various modifications and changes can be made to the present disclosure. Any modification, equivalent replacement, improvement, and the like made within the spirit and principle of the present disclosure shall be included within the protective scope of the present invention.

Industrial Applicability

(1) The present disclosure overcomes the limitation that the main products of nickel oxide ore are nickel-iron alloys used in the field of stainless steel, which is difficult to be used in battery materials, and provides nickel resource guarantee for the huge demand for nickel intermediate products in the field of battery materials in the future.

(2) In the present disclosure, coke powder or pulverized coal is used as fuel and the reducing agent, and sulfur powder or calcium sulfate is used as the sulfidation agent. The reducing agent and the sulfidation agent are directly sprayed into the hearth of the reaction area. Therefore, the present disclosure has high utilization efficiency of the reducing agent and the sulfdation agent, easily controllable atmosphere, high sulfidation efficiency, low load of the flue gas desulfurization system, and low cost for flue gas treatment.

(3) Compared with the existing blast furnace and air furnace smelting processes that use coke as fuel, in the entire process of the present disclosure, coal or coke powder is used as fuel and the reducing agent, smelting is performed in a high-concentration, oxygen-enriched environment, the materials are fed into the furnace in a hot state, and thus the system has low energy consumption and high efficiency.

(4) The present disclosure has good adaptability of raw materials, can treat nickel oxide ore with high magnesium and aluminum contents as compared with the wet process, and the product is low nickel matte as compared with the electric furnace process. The cobalt in nickel oxide ore can be recovered and can be used subsequently in the field of battery materials. The produced low nickel matte has higher grade and higher recovery rates of nickel and cobalt.

(5) Compared with the wet process, the smelting slag produced is stable in nature, does not pollute the environment. The process of the present disclosure has good adaptability of raw materials, and can treat nickel oxide ore with high magnesium and aluminum contents.

Claims (15)

1. Claims: 1. A method for producing low nickel matte by smelting, reduction and sulfidation of nickel oxide ore, the method comprising:

   (1) drying and preheating, comprising drying and preheating nickel oxide ore to produce hot-state nickel oxide ore with a temperature of 600-900°C; and

   (2) smelting, reduction and sulfidation, comprising continuously feeding the dried and preheated nickel oxide ore and a flux into a hearth of a smelting furnace; spraying a reducing agent, a sulfidation agent, and oxygen-enriched air into a reaction zone of the hearth in the smelting furnace, with an oxygen excess coefficient a of the oxygen-enriched air relative to the reducing agent being controlled to 0.3-0.4; and controlling a temperature inside the furnace to 1400-1550°C, whereby materials added in the smelting furnace undergo a reduction and sulfidation reaction in a molten state, producing low nickel matte and slag.
2. 2. The method for producing low nickel matte by smelting, reduction and sulfidation of nickel oxide ore according to claim 1, wherein step (1) further comprises screening the preheated hot-state nickel oxide ore to control a particle size of the hot-state nickel oxide ore fed into the smelting furnace to be less than 50 mm.
3. 3. The method for producing low nickel matte by smelting, reduction and sulfidation of nickel oxide ore according to claim 1, wherein a high-temperature flue gas generated during the melting, and the reduction and sulfidation reaction is returned to step (1) for drying and preheating the nickel oxide ore.
4. 4. The method for producing low nickel matte by smelting, reduction and sulfidation of nickel oxide ore according to claim 1, wherein a flue gas generated during the melting, and the reduction and sulfidation reaction is dedusted and then fed into a desulfurization system for desulfurization, with calcium oxide or calcium carbonate as a desulfurizing agent, and calcium sulfate produced during a desulfurization process is returned to step (2) to be used as a flux and a sulfidation agent.
5. 5. The method for producing low nickel matte by smelting, reduction and sulfidation of nickel oxide ore according to claim 1, wherein the flux is at least one of calcium sulfate and calcium carbonate, and in the smelting, reduction and sulfidation step, the flux is added to give a mass ratio of the nickel oxide ore to the flux of 100:5-15.
6. 6. The method for producing low nickel matte by smelting, reduction and sulfidation of nickel oxide ore according to claim 1, wherein the reducing agent is coke powder, bituminous coal, or anthracite, greater than 80% of amount of the reducing agent has a particle size of 200 mesh or more, and a mass ratio of amounts of the nickel oxide ore to the reducing agent added is 100:15-25.
7. 7. The method for producing low nickel matte by smelting, reduction and sulfidation of nickel oxide ore according to claim 1, wherein the sulfidation agent is at least one of sulfur and calcium sulfate, the nickel oxide ore and the sulfidation agent are added in a mass ratio of the nickel oxide ore to sulfur of 100:2-4.
8. 8. The method for producing low nickel matte by smelting, reduction and sulfidation of nickel oxide ore according to claim 1, wherein the sulfidation agent is at least one of sulfur and calcium sulfate, the sulfidation agent is sprayed into the smelting furnace in powder form, and greater than 80% of amount of the sulfidation agent has a particle size of 100 mesh or more.
9. 9. The method for producing low nickel matte by smelting, reduction and sulfidation of nickel oxide ore according to claim 1, wherein the sulfidation agent is sulfur, and the sulfidation agent is sprayed into the reaction zone of the hearth in the smelting furnace in liquid form.
10. 10. The method for producing low nickel matte by smelting, reduction and sulfidation of nickel oxide ore according to claim 1, wherein in the smelting, reduction and sulfidation step, a volume concentration of oxygen in the oxygen-enriched air sprayed into the reaction zone of the hearth in the smelting furnace is 80-95%.
11. 11. The method for producing low nickel matte by smelting, reduction and sulfidation of nickel oxide ore according to claim 1, wherein in the smelting, reduction and sulfidation step, the reducing agent and the sulfidation agent are sprayed into the reaction zone of the hearth through compressed air, and pressures of the oxygen-enriched air and the compressed air for transporting the reducing agent and the sulfidation agent are 0.2 Mpa-0.4 Mpa.
12. 12. The method for producing low nickel matte by smelting, reduction and sulfidation of nickel oxide ore according to claim 1, wherein the method further comprises spraying the oxygen-enriched air into a gas phase space above a liquid level in the furnace for a second time, to bum carbon monoxide in the gas phase space above the liquid level in the furnace.
13. 13. The method for producing low nickel matte by smelting, reduction and sulfidation of nickel oxide ore according to claim 10, wherein a volume concentration of oxygen in the oxygen-enriched air sprayed for the second time is 60-80%, and a pressure of the oxygen-enriched air sprayed for the second time is 0.05 Mpa-0.1 Mpa.
14. 14. The method for producing low nickel matte by smelting, reduction and sulfidation of nickel oxide ore according to claim 1, wherein a metallization rate Meform of a produced low nickel matte is controlled to be 0.20-0.35, and the metallization rate Meformof the low nickel matte is expressed by a value obtained by dividing a difference between a theoretical content Stheoy of sulfur in the low nickel matte and an actual content Sactuai of sulfur in the low nickel matte by the theoretical content Stheory of sulfur in the low nickel matte, that is, Meorm = (Stheory - Sactual)/ Stheory, where the theoretical content Stheoy of sulfur is a theoretical sulfur content when iron, nickel, and cobalt in the low nickel matte are completely sulfided.
15. 15. The method for producing low nickel matte by smelting, reduction and sulfidation of nickel oxide ore according to claim 1, wherein a reaction time of the smelting, reduction and sulfidation of the materials in the smelting furnace is 1-1.5 h.