CN109097562B

CN109097562B - Method for selectively vulcanizing and roasting laterite-nickel ore

Info

Publication number: CN109097562B
Application number: CN201810787258.9A
Authority: CN
Inventors: 韩俊伟; 刘维; 覃文庆; 焦芬; 张添富; 李琛; 梁超
Original assignee: Hunan Rui Zi Zhi Ring Technology Co Ltd; Central South University
Current assignee: Central South University
Priority date: 2018-07-18
Filing date: 2018-07-18
Publication date: 2020-03-31
Anticipated expiration: 2038-07-18
Also published as: CN109097562A

Abstract

The invention discloses a method for selectively vulcanizing and roasting laterite-nickel ore, which is characterized in that laterite-nickel ore and raw materials containing a carbonaceous reducing agent, a vulcanizing agent, an alkali metal salt additive and a binder are uniformly mixed and pelletized, and the obtained pellet material is sequentially subjected to first-stage roasting at low temperature and second-stage roasting at high temperature; the roasted material is subjected to a flotation method to recover nickel products, and the flotation tailings are subjected to a magnetic separation method to recover iron products.

Description

Method for selectively vulcanizing and roasting laterite-nickel ore

Technical Field

The invention relates to a treatment method of laterite-nickel ore, in particular to a method for selectively converting nickel into nickel sulfide ore which is easy to float and separate and selectively converting iron into magnetite which is easy to magnetically separate by reducing-vulcanizing roasting laterite-nickel ore, belonging to the field of nonferrous metallurgy technology and ore dressing.

Background

Nickel is an important strategic metal material and is widely applied to the aspects of stainless steel production, alloy manufacturing, new energy battery production and the like. The world nickel resource reserves are about 4.7 hundred million tons, the laterite nickel ore accounts for 70 percent, the nickel sulfide ore accounts for 30 percent, and 60 percent of nickel in the world is extracted from the nickel sulfide ore, but with the increasing exhaustion of the nickel sulfide ore resource, the economic development and utilization of the laterite nickel ore are more and more paid attention. Laterite-nickel ore is mainly divided into limonite type and silicon-magnesium type according to ore deposit types, and the existing smelting method of laterite-nickel ore mainly comprises a fire method process and a wet method process.

The fire process mainly comprises a ferronickel reduction smelting process and a nickel matte reduction smelting preparation process. The ferronickel process is characterized in that laterite-nickel ore is dried and pre-reduced and then smelted in an electric furnace at 1550-1600 ℃, ferronickel with the nickel grade of 25% can be obtained, the process is short in flow, strong in technological adaptability, high in nickel recovery rate, capable of producing high-grade high-quality ferronickel on a large scale, and free of waste residue and waste water in the production process, but high in energy consumption and serious in environmental pollution, cannot recover cobalt in raw materials, and is not suitable for ore with high cobalt content. The nickel matte process is characterized in that a vulcanizing agent is added in the smelting process of 1550-1600 ℃ for producing the ferronickel to produce low-nickel matte, and then the high-nickel matte is produced by converting through a converter, so that the process realizes the comprehensive utilization of cobalt resources, can produce nickel products in various forms, and has short process flow and simple operation; but the smelting process needs to consume a large amount of high-quality coke, so that the energy consumption is very high; the produced harmful gas of sulfur dioxide has great pollution to the environment and poor adaptability of raw materials.

The wet process mainly comprises a reduction-ammonia leaching process, a high-pressure acid leaching process and a normal-pressure acid leaching process. The reduction-ammonia leaching process is also called Caron process, and the process comprises the steps of firstly reducing nickel and cobalt in the laterite-nickel ore into metal simple substances through reduction roasting, and then leaching the nickel and cobalt by adopting ammonia-ammonium carbonate solution, thereby realizing the effective separation of the nickel and cobalt from gangue; the mass fraction of nickel in the nickel block produced by the process can reach 90 percent, and the recovery rate of the nickel in the whole process can reach 75 to 80 percent. Compared with the pyrometallurgical process, the cobalt can be partially recovered, and the recovery rate is 40-50%. However, the ammonia leaching method is only suitable for processing laterite on the upper layer of the laterite-nickel ore bed, and is not suitable for processing the lower layer of ore bed with high silicon and magnesium content. The high-pressure acid leaching process is characterized in that under the conditions of 250-270 ℃ and 4-5 MPa, valuable metals such as nickel, cobalt and the like are dissolved with iron and aluminum minerals by sulfuric acid, leaching conditions are controlled to enable dissolved impurity elements to be hydrolyzed to enter slag, nickel and cobalt enter solution, the leaching rate of cobalt in the process can reach more than 90%, but the process is only suitable for treating laterite-nickel ore with low content of magnesium oxide, the factory investment is high, the equipment is seriously corroded, the maintenance difficulty is high, and the production efficiency is greatly reduced. The normal pressure sulfuric acid leaching method is to mix the laterite nickel ore with washing liquid and sulfuric acid according to a certain proportion and leach nickel under the condition of heating, the neutralized liquid of the leaching liquid is subjected to solid separation, the obtained leaching liquid uses calcium oxide or sodium sulfide as a precipitator to precipitate nickel, the process is simple, the energy consumption is low, an autoclave is not used, the investment cost is low, the operation condition is easy to control, but the leaching liquid is difficult to separate, and the nickel content in the leaching slag is high.

In summary, the problems of high energy consumption, serious environmental pollution, low nickel recovery rate and the like generally exist in the pyrometallurgical process, and although the nickel and cobalt recovery rates are high, the general flow is overlong, the process is complex and the requirement on equipment is strict.

Disclosure of Invention

Aiming at the problems of long flow, large energy consumption, high cost and the like existing in the pyrometallurgical process of the laterite-nickel ore in the prior art, the invention aims to provide the method for converting nickel and iron in the laterite-nickel ore into the nickel sulfide ore which is easy to float and recover and the magnetite which is easy to magnetically separate and recover respectively through reduction-sulfuration roasting to realize the high-efficiency separation and recovery of the nickel and iron and other metals.

In order to realize the technical purpose, the invention provides a method for reducing, vulcanizing and roasting laterite-nickel ore, which comprises the steps of uniformly mixing laterite-nickel ore and raw materials containing a carbonaceous reducing agent, a vulcanizing agent, an alkali metal salt additive and a binder for pelletizing, and roasting the obtained pellets at 400-450 ℃ and 700-1100 ℃ in sequence; the roasted material is subjected to a flotation method to recover a nickel product, and the flotation tailings are subjected to a magnetic separation method to recover an iron product.

According to the technical scheme, the roasting process of the pellet is mainly divided into two sections, the first section roasting is carried out at a lower temperature of about 430 ℃, nickel in the laterite-nickel ore is made to fully react with liquid sulfur, the volatilization loss of the sulfur is reduced, the vulcanization efficiency is improved, then the temperature is raised to be above 700 ℃ for second section roasting, and the purpose is to enable nickel sulfide and ferroferric oxide grains to gather and grow, so that the subsequent flotation and magnetic separation are facilitated.

In the preferable scheme, the mass of the carbonaceous reducing agent is 2.5-10% of that of the laterite-nickel ore. A proper amount of reducing agent is beneficial to promoting the sulfuration of nickel and the magnetization of iron, but the excessive addition of the reducing agent can reduce nickel into metal, so that the sulfuration effect is poor; too small an amount of the reducing agent not only increases the consumption of sulfur but also is not favorable for the magnetization of iron.

In the preferable scheme, the mass of the vulcanizing agent is 2.5-15% of that of the laterite-nickel ore. Too little vulcanizing agent is added, the nickel is not completely vulcanized, too much vulcanizing agent is added, the iron is also vulcanized, and the selectivity is poor.

In a preferable scheme, the mass of the alkali metal salt additive is 2.5-15% of that of the laterite-nickel ore. The addition of the alkali metal salt reduces the surface tension and melting point of nickel sulfide and ferroferric oxide crystal grains, reduces the temperature of the sulfuration conversion of nickel and the magnetization conversion of iron, and is beneficial to the aggregation and growth of the nickel sulfide and the ferroferric oxide crystal grains.

In the preferable scheme, the mass of the binder is 2.5-5% of that of the laterite-nickel ore.

More preferably, the carbonaceous reducing agent includes at least one of charcoal, coke and pulverized coal.

In a more preferable scheme, the vulcanizing agent is sulfur and/or pyrite.

More preferably, the alkali metal salt additive comprises at least one of sodium carbonate, sodium sulfate and sodium chloride.

More preferably, the binder includes at least one of CMC, gelatinized starch, and bentonite.

In the preferable scheme, the laterite-nickel ore is dried until the moisture content is lower than 5%, crushed and sieved by a 5mm sieve, and the sieved laterite-nickel ore powder is taken for pelletizing.

In a preferred scheme, the laterite-nickel ore is limonite type and/or low-magnesium type.

In a preferable scheme, the diameter of the pellet material is 25-50 mm.

In the preferable scheme, the roasting time is 1-3 h at the temperature of 400-450 ℃.

In the preferable scheme, the roasting time is 0.5-2 h at the temperature of 700-1100 ℃.

In the preferable scheme, during the flotation, the roasted product is wet-ground until the ore pulp granularity of-74 um accounts for 75-85%, and amyl xanthate and/or isopropyl xanthate are/is used as flotation collectors.

In a preferable scheme, the magnetic field intensity adopted by the magnetic separation method is 0.4-1.2 KGs.

The invention relates to a method for reducing, vulcanizing and roasting laterite-nickel ore, which comprises the following specific steps:

the method comprises the following steps: drying, crushing and sieving

Drying the laterite-nickel ore until the water content is lower than 5%, and then crushing and sieving the laterite-nickel ore through a 5mm sieve; the laterite-nickel ore is limonite type and low-magnesium type;

step two: pelletizing

Uniformly mixing the laterite-nickel ore dried, crushed and screened in the step one with a carbonaceous reducing agent, a vulcanizing agent, an alkali metal salt additive and a binder to prepare pellets; the reducing agent is at least one of charcoal, coke or pulverized coal, and the addition amount of the reducing agent is 2.5-10%; the additive is one of sodium sulfate and sodium carbonate, and the addition amount of the additive is 2.5-15%; the addition amount of the vulcanizing agent sulfur is 2.5-15%; the addition amount of the binder CMC, bentonite or gelatinized starch is 2.5 to 5 percent; the diameter of the pellet is 25-50 mm;

step three: roasting by sulfurization

Placing the pellets in the second step into a rotary kiln, roasting for 1-3 h at 400-450 ℃ in the first stage, heating to 700-1100 ℃ in the second stage, and roasting for 0.5-2 h;

step four: flotation

Wet grinding the roasted product in the step three until the ore pulp granularity is-74 um and accounts for 75-85%, and then recovering nickel sulfide by adopting a conventional flotation method; the collecting agent is one of amyl xanthate or isopropyl xanthate;

step five: magnetic separation

Recovering iron from the flotation tailings obtained in the fourth step by adopting magnetic separation; the magnetic field intensity of the flotation tailings is 0.4-1.2 KGs.

Aiming at the problems of poor raw material adaptability, high energy consumption, high cost and the like of the existing pyrometallurgical process of the laterite-nickel ore, the invention firstly provides the method for realizing the selective conversion of nickel and iron in the laterite-nickel ore through reduction-sulfuration roasting, nickel is converted into nickel sulfide ore, iron is converted into magnetite ore, and the generation of liquid phase in the high-temperature reaction process is promoted through an alkali metal salt additive, so that an effective channel for gathering and growing iron sulfide and ferroferric oxide grains is provided, nickel sulfide and ferroferric oxide grains with larger grain sizes are obtained, the subsequent reference of the flotation method in the prior art for recovering nickel sulfide ore is facilitated, and the magnetite ore is recovered by adopting a magnetic separation method, so that the high-efficiency separation and recovery.

Compared with the prior art, the technical scheme of the invention has the beneficial technical effects that:

1) according to the invention, nickel and iron in the laterite-nickel ore can be respectively converted into the nickel sulfide ore easy to float and recover and the magnetite easy to magnetically separate and recover through a reduction-sulfuration roasting process, and the regulation and control of phase grains of the nickel and iron are realized through an alkali metal salt additive and reaction temperature control, so that the nickel and iron can be efficiently separated and recovered from other metals by means of the existing magnetic separation and flotation methods.

2) The invention adopts two-stage roasting, the first stage roasting is carried out at the temperature lower than the boiling point of the sulfur, the volatilization of the sulfur can be effectively reduced, the utilization rate of the sulfur is improved, the temperature of the second stage roasting is increased, the aggregation and growth of ferronickel crystal grains are promoted, the recovery rate of nickel and iron is improved, and compared with the traditional nickel matte process, the invention has the advantages of low roasting temperature, low energy consumption, low sulfur consumption and small environmental pollution.

3) The reduction-vulcanization roasting product of the invention adopts a flotation method and a magnetic separation method to recover nickel and iron respectively, and has short process, low cost and large enrichment ratio.

4) The nickel in the flotation concentrate exists in the form of sulfide, and the high-nickel matte obtained by converting in a converter can be used for producing general nickel and can also be used as a raw material for refining nickel by a normal-pressure carbonyl method to produce nickel pills and nickel powder; the magnetic concentrate can be directly used as iron-making raw material.

5) The reducing agent of the invention, such as reduction-sulfuration roasting charcoal, coke or powdered coal, has less consumption, less energy consumption and low cost.

6) The reducing sulfuration-roasting of the invention greatly reduces the surface tension and melting point of nickel sulfide and ferroferric oxide crystal grains and reduces the sulfuration conversion of nickel and the magnetization conversion temperature of iron by adding sodium carbonate or sodium sulfate and the like as roasting additives.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

The following examples are intended to further illustrate the present disclosure, but not to limit the scope of the claims.

The following describes in further detail a specific implementation of the present invention with reference to fig. 1.

The main chemical elements of the limonite type laterite-nickel ore are shown in the table 1.

TABLE 1 composition/% of main chemical constituents of limonitic laterite-nickel ore (dry basis)

Example 1

Drying the laterite-nickel ore until the moisture content is lower than 5%, crushing, sieving with a 5mm sieve, uniformly mixing with 10% of sodium carbonate, 7.5% of charcoal, 5% of sulfur and 3% of CMC (carboxymethyl cellulose) for pelletizing, wherein the pellet diameter is 25-50 mm, placing the pellets in a self-made rotary kiln, firstly roasting at 400 ℃ for 2h, then heating to 1000 ℃ for roasting for 1.5h, and cooling to room temperature under the protection of nitrogen; phase analysis results show that 90% of nickel in the calcine exists in a sulfide form, and more than 85% of iron exists in a ferroferric oxide form; finely grinding the roasted product in a grinding machine until the granularity of ore pulp is-74 mu m and accounts for 80 percent, and adopting amyl xanthate as a collecting agent to float nickel to obtain nickel concentrate with 8.3 percent of nickel and 78.6 percent of nickel recovery rate; the flotation tailings are magnetically separated under the magnetic field intensity of 0.5KGs, so that iron ore concentrate with the iron grade of 79.4% and the recovery rate of 78.5% can be obtained.

Example 2

Drying the laterite-nickel ore until the moisture content is lower than 5%, crushing, sieving by a 5mm sieve, uniformly mixing with 5% of sodium sulfate, 5% of coke, 15% of sulfur and 5% of bentonite by mass, pelletizing, wherein the diameter of the pellet is 25-50 mm, placing the pellet in a self-made rotary kiln, firstly roasting at 400 ℃ for 3h, then heating to 950 ℃ for roasting for 1h, and cooling to room temperature under the protection of nitrogen; phase analysis results show that more than 95% of nickel in the calcine exists in a sulfide form, and more than 78% of iron exists in a ferroferric oxide form; finely grinding the roasted product in a grinding machine until the granularity of ore pulp is-74 mu m and accounts for 75 percent, and adopting isopropyl xanthate as a collecting agent to float nickel to obtain nickel concentrate with 6.8 percent of nickel and 84.3 percent of nickel recovery rate; the flotation tailings are magnetically separated under the magnetic field intensity of 0.8KGs, so that iron ore concentrate with the iron grade of 71.6% and the recovery rate of 73.1% can be obtained.

Example 3

Drying the laterite nickel ore until the moisture content is lower than 5%, crushing, sieving by a 5mm sieve, uniformly mixing with 5% of sodium sulfate, 5% of sodium carbonate, 10% of pulverized coal, 7.5% of sulfur and 2.5% of gelatinized starch, pelletizing, wherein the pellet diameter is 25-50 mm, placing the pellets in a self-made rotary kiln, firstly roasting at 400 ℃ for 2h, then heating to 950 ℃ for roasting for 2h, and cooling to room temperature under the protection of nitrogen; phase analysis results show that more than 92% of nickel in the roasted product exists in a sulfide form, and more than 82% of iron exists in a ferroferric oxide form; finely grinding the roasted product in a grinding machine until the granularity of ore pulp is-74 mu m and accounts for 85 percent, and floating the nickel sulfide by adopting isopropyl xanthate as a collecting agent to obtain nickel concentrate containing 7.8 percent of nickel and the recovery rate of the nickel of 81.8 percent; the flotation tailings are magnetically separated under the magnetic field intensity of 0.4KGs, and iron ore concentrate with the iron grade of 79.5% and the recovery rate of 81.1% can be obtained.

Comparative example 1

Drying the laterite-nickel ore until the moisture content is lower than 5%, crushing, sieving by a 5mm sieve, uniformly mixing with pulverized coal accounting for 10% of the mass fraction of the crushed laterite-nickel ore, sulfur accounting for 7.5% of the mass fraction of the crushed laterite-nickel ore, and bentonite accounting for 2.5% of the mass fraction of the crushed laterite-nickel ore, pelletizing, wherein the diameter of the pellets is 25-50 mm, placing the pellets in a self-made rotary kiln, firstly roasting at 400 ℃ for 2h, then heating to 750 ℃ for roasting for 2h, and; phase analysis results show that 78% of nickel in the calcine exists in a sulfide form, 85% of iron exists in a ferroferric oxide form, a roasting product is finely ground in a grinding machine until the granularity of ore pulp is-74 mu m and accounts for 80%, isopropyl xanthate is used as a collecting agent to float nickel sulfide, the grade of the obtained nickel concentrate is only 3.9%, and the recovery rate is only 69.2%; magnetically separating the flotation tailings under the condition that the magnetic field intensity is 0.6KGs, wherein the iron grade of the obtained iron ore concentrate is 65.6 percent, and the recovery rate is 70.1 percent; when the nickel is roasted without adding alkali metal salt, the sulfuration conversion rate of the nickel is low, and the recovery rate of the roasted product nickel is not ideal.

Comparative example 2

Drying the laterite-nickel ore until the moisture content is lower than 5%, crushing, sieving with a 5mm sieve, uniformly mixing with 10% of sodium carbonate, 10% of charcoal, 5% of sulfur and 3% of gelatinized starch, pelletizing, wherein the pellet diameter is 25-50 mm, placing the pellets in a self-made rotary kiln, heating to 1000 ℃, roasting for 3 hours, and cooling to room temperature under the protection of nitrogen; phase analysis results show that 53% of nickel in the calcine exists in a sulfide form, 88% of iron exists in a ferroferric oxide form, the calcine is finely ground in a grinding machine until the granularity of ore pulp is-74 mu m and accounts for 80%, the amyl xanthate is used as a collecting agent for flotation of nickel, nickel in nickel concentrate is 5.1%, and the recovery rate is only 42.3%; magnetically separating the flotation tailings under the condition that the magnetic field intensity is 0.3KGs to obtain iron concentrate with the iron grade of 76.4 percent and the recovery rate of 79.5 percent; only one-stage roasting is adopted during roasting, so that a large amount of sulfur is volatilized, the vulcanization rate of nickel is low, and the flotation effect is poor.

Comparative example 3

Drying the laterite-nickel ore until the moisture content is lower than 5%, crushing, sieving with a 5mm sieve, uniformly mixing with 10% of sodium carbonate, 10% of sulfur and 3% of CMC (carboxymethyl cellulose) for pelletizing, wherein the pellet diameter is 25-50 mm, placing the pellets in a self-made rotary kiln, firstly roasting at 400 ℃ for 2h, then heating to 1000 ℃ for roasting for 1.5h, and cooling to room temperature under the protection of nitrogen; phase analysis results show that 45% of nickel in the roasted product exists in a sulfide form, and 35% of iron exists in a ferroferric oxide form; finely grinding the roasted product in a grinding machine until the ore pulp granularity is-74 mu m accounting for 80%, and adopting amyl xanthate as a collecting agent to float nickel, wherein the nickel grade of the obtained nickel concentrate is 4.6%, and the recovery rate is only 28.6%; the flotation tailings are magnetically separated under the condition that the magnetic field intensity is 0.5KGs, the iron grade of the iron ore concentrate is only 63.2 percent, and the recovery rate is 58.5 percent; no reducing agent is added during roasting, and the sulfuration effect of nickel and the magnetization effect of iron are not ideal.

COMPARATIVE EXAMPLE 4 (reductive calcination-Ammonia leaching Process)

Drying, screening and crushing the laterite-nickel ore, uniformly mixing the laterite-nickel ore with pulverized coal, placing the mixture in a rotary kiln, reducing and roasting the mixture at 1000 ℃ for 90min, cooling the reduced and roasted product, and leaching the cooled product in an ammonia-ammonium carbonate solution for 120 min; the leaching rate of nickel is 87.5 percent, and the mass fraction of iron in the leached slag is 62 percent.

Claims

1. A method for selectively vulcanizing and roasting laterite-nickel ore is characterized by comprising the following steps: uniformly mixing laterite-nickel ore and raw materials containing a carbonaceous reducing agent, sulfur, an alkali metal salt additive and a binder for pelletizing, and sequentially roasting the obtained pellets for 1-3 hours at the temperature of 400-450 ℃ and 0.5-2 hours at the temperature of 700-1100 ℃; recovering nickel products from the roasted material by a flotation method, and recovering iron products from flotation tailings by a magnetic separation method;

the mass of the carbonaceous reducing agent is 2.5-10% of that of the laterite-nickel ore;

the mass of the sulfur is 2.5 to 15 percent of that of the laterite-nickel ore;

the mass of the alkali metal salt additive is 2.5-15% of that of the laterite-nickel ore;

the mass of the binder is 2.5-5% of that of the laterite-nickel ore.

2. The method for selective sulfidation roasting of lateritic nickel ores according to claim 1, characterized in that: the carbonaceous reducing agent comprises at least one of charcoal, coke and pulverized coal;

the alkali metal salt additive comprises at least one of sodium carbonate, sodium sulfate and sodium chloride;

the binder comprises at least one of CMC, gelatinized starch and bentonite.

3. The method for selective sulfidation roasting of lateritic nickel ores according to claim 1, characterized in that: drying the laterite-nickel ore until the moisture content is lower than 5%, crushing and sieving by a 5mm sieve, and taking the sieved laterite-nickel ore powder for pelletizing.

4. The method for selective sulfidation roasting of lateritic nickel ores according to claim 3, characterized in that: the laterite-nickel ore is limonite type and/or low-magnesium type.

5. The method for selective sulfidation roasting of lateritic nickel ores according to claim 1, characterized in that: the diameter of the pellet material is 25-50 mm.

6. The method for selective sulfidation roasting of lateritic nickel ores according to claim 1, characterized in that: the flotation adopts amyl xanthate and/or isopropyl xanthate as flotation collectors.

7. The method for selective sulfidation roasting of lateritic nickel ores according to claim 1, characterized in that: the magnetic field intensity adopted by the magnetic separation is 0.4-1.2 KGs.