A resource recovery method for recovering iron from laterite nickel ore high-pressure leaching residue

Abstract

The application discloses a resource recycling method for recovering iron from laterite nickel ore high-pressure leaching residue, and comprises the following steps: (1) mixing and stirring the laterite nickel ore high-pressure leaching residue and a binder, then obtaining pellets through a pelletizing process, and drying the pellets to obtain dry pellets; (2) mixing the dry pellets with pyrite, and heating and roasting the mixture in an oxygen atmosphere to obtain roasted material and flue gas, wherein the flue gas is subjected to an acid-making process to obtain sulfuric acid; (3) mixing the roasted material, a fluxing agent and a reducing agent, and then heating and smelting the mixture to obtain molten iron, smelting slag and flue gas. The resource recycling method combines the heating roasting process with the heating smelting process to process the laterite nickel ore high-pressure leaching residue, realizes efficient recovery and utilization of the iron in the laterite nickel ore high-pressure leaching residue, can effectively reduce the sulfur element in the product, is convenient for resource utilization of the product, and can improve the concentration of SO2 in the flue gas, so that the sulfur element removed in the step is also fully utilized.

Description

Technical Field

[0001] This invention belongs to the field of waste residue utilization, and in particular relates to a method for recovering high-pressure leaching residue from laterite nickel ore. Background Technology

[0002] With the rapid development of the new energy industry, the demand for power batteries has increased dramatically, making the need for nickel even more urgent. Efficient extraction of nickel resources is of great significance for promoting the sustainable development of my country's new energy industry. Laterite nickel ore is an important nickel extraction resource. High-pressure acid leaching is one of the mainstream processes for processing laterite nickel ore. This method uses an acidic solution to leach valuable metals from laterite nickel ore under special conditions of high temperature and pressure, and is suitable for processing limonite-type laterite nickel ore with a nickel content greater than 1.3%. During the high-pressure acid leaching process, producing 10,000 tons of metallic nickel will generate 1.3-1.6 million tons of high-pressure leaching residue.

[0003] Currently, the main method for treating high-pressure leaching residue from laterite nickel ore is direct stockpiling. However, this residue contains heavy metals, and its stockpiling not only wastes resources but also poses ecological safety risks such as the leaching of harmful ions. Iron is the main component of high-pressure leaching residue from laterite nickel ore. Efficiently recovering the iron from the residue and using it for iron / steelmaking could significantly reduce iron resource waste, improve resource utilization, and benefit ecological safety. However, there is currently no effective iron recovery pathway for high-pressure leaching residue from laterite nickel ore; therefore, there is an urgent need to develop new methods for treating this residue to recover iron. Summary of the Invention

[0004] The technical problem to be solved by this invention is to overcome the shortcomings and defects mentioned in the background art above, and to provide a resource-based recovery method for iron from high-pressure leaching residue of laterite nickel ore. This recovery method has the advantages of high iron recovery rate and high sulfur utilization rate. To solve the above technical problem, the technical solution proposed by this invention is as follows:

[0005] A resource recovery method for recovering iron from high-pressure leaching residue of laterite nickel ore includes the following steps:

[0006] (1) The high-pressure leaching residue of laterite nickel ore and the binder are mixed and stirred, and then pellets are obtained through a pelletizing process and dried to obtain dried pellets.

[0007] (2) The dried pellets are mixed with pyrite and heated and roasted in an oxygen atmosphere to obtain roasting material and flue gas. The flue gas is then processed to obtain sulfuric acid.

[0008] (3) The roasting material, flux and reducing agent are mixed and then heated and smelted to obtain molten iron, slag and flue gas. The slag can be used as cement clinker.

[0009] In the above-mentioned resource recovery method, preferably, the high-pressure leaching residue of laterite nickel ore contains 40-60% iron, 0.8-1.5% chromium, 0.5-1.5% aluminum, 0.1-0.5% magnesium, and 1-2.5% sulfur by mass, with the sulfur mainly existing in the form of sulfate; the binder includes one or more of bentonite, hydrated lime, and quicklime, and the mass ratio of the high-pressure leaching residue of laterite nickel ore to the binder is (80-90):(10-20); the drying temperature is controlled at 100-150℃, and the drying time is 1-3 hours. Because the particle size of the high-pressure acid leaching residue of laterite nickel ore is very small, if it is directly smelted without pelletizing, it will result in a large amount of dust and low resource utilization. Adding a binder to form pellets can effectively avoid the above problems. The binder can improve the pelletizing properties of the material, and because the binder may contain components such as calcium oxide, adding a binder can adjust the chemical composition of the pellets. Adding too much binder reduces the permeability of the green pellets, hindering the escape of water vapor and increasing production costs; adding too little binder results in low compressive strength and easy breakage of the pellets. The purpose of drying is mainly to evaporate the moisture from the pellets; to maintain the activity of the binder, the drying temperature should not exceed 150℃.

[0010] In the above-mentioned resource recovery method, preferably, the mass ratio of the dried pellets to pyrite is controlled at (90-95):(5-10). The amount of pyrite added should be reasonably controlled. If too much pyrite is added, it will increase the cost and the pressure on the subsequent acid production process. In addition, if too much pyrite is added, the pyrite may not react fully, which will increase the sulfur content in the roasted material and will not be conducive to obtaining molten iron with low sulfur content in step (3). If too little pyrite is added, the sulfur dioxide concentration in the flue gas will be too low, and it cannot be used to produce acid. Moreover, its effect on promoting the decomposition of sulfate is limited.

[0011] In the above-mentioned resource recovery methods, preferably, the roasting temperature is controlled at 800-1000℃ and the roasting time is 1-4 hours. Excessive roasting temperature and time will increase energy consumption; insufficient roasting temperature and time will affect the full reaction of pyrite, resulting in incomplete sulfate decomposition and consequently high sulfur content in the roasted material.

[0012] In the above-mentioned resource recovery methods, preferably, oxygen is introduced during heating and roasting, and the oxygen introduction rate is 30-100 mg / ton of dried pellets under standard atmospheric pressure. 3 .

[0013] In the above-mentioned resource recovery method, preferably, the volume concentration of SO2 in the flue gas obtained in step (2) is greater than 3.5%, and the mass content of sulfur in the roasting material is less than 0.25%. The flue gas can be directly used for acid production, and the sulfur content in the roasting material is low, resulting in even lower sulfur content in the molten iron obtained subsequently, which can be directly used in the steelmaking process.

[0014] The purpose of this invention is to recover molten iron from high-pressure acid leaching slag of laterite nickel ore for direct use in the steelmaking process. Sulfur is a harmful element in steelmaking, and generally, the lower the sulfur content in molten iron, the better. To make it a resource, the sulfur in the raw materials needs to be pretreated, typically requiring a sulfur mass fraction in the molten iron of less than 0.04%. Although sulfur can be removed during the steelmaking process, it reduces furnace productivity and increases raw material consumption. The purpose of the heating roasting method in this invention is mainly to decompose sulfates and remove some of the sulfur from the raw materials to avoid adverse effects on subsequent smelting. Furthermore, this invention incorporates pyrite for co-processing during heating and roasting. The addition of pyrite has two main functions: first, under oxidizing conditions, pyrite can decompose sulfates containing metals such as nickel and iron, promoting sulfate decomposition and reducing the sulfur content in the roasted material; second, pyrite decomposes in an oxidizing atmosphere to produce SO2, which can increase the SO2 concentration in the roasting flue gas, facilitating acid production. This allows for the full utilization of low-concentration flue gas that was originally unsuitable for use (if pyrite is not added, the flue gas produced by direct heating and roasting has low SO2 content and is not suitable for acid production). This reduces the cost of tail gas treatment while also enabling the resource utilization of tail gas.

[0015] In the above-mentioned resource recovery method, preferably, the flux includes one or more of limestone, quicklime, and hydrated lime, and the amount of flux added is 5-10% of the mass of the calcined material. The main function of the flux is to adjust the slag shape, maintain the slag's good fluidity, and facilitate slag-metal separation.

[0016] In the above-mentioned resource recovery method, preferably, the reducing agent includes a solid reducing agent and a gaseous reducing agent. The solid reducing agent includes one or more of anthracite, bituminous coal, and coke, and the gaseous reducing agent includes one or more of hydrogen, carbon monoxide, water gas, and natural gas. The amount of reducing agent added is calculated separately for solid reducing agents, and the amount of reducing agent added is 4-8% of the mass of the roasted material. The amount of reducing agent added is calculated separately for gaseous reducing agents, and the rate of introduction of the reducing agent is 150-300 m³ per ton of roasted material under standard atmospheric pressure. 3 .

[0017] In the above-mentioned resource recovery methods, preferably, the melting temperature is controlled at 1400-1550℃ and the melting time is 2-4 hours. If the melting temperature is too low, the material may not melt completely, resulting in high viscosity and poor recovery effect; if the melting temperature is too high, the melt will have excessive fluidity, which will aggravate the erosion of the furnace lining and reduce the service life of the furnace.

[0018] In the above-mentioned resource recovery method, preferably, the molten iron has a content of elemental iron of 95% or more and a sulfur content of less than 0.04%. The high iron content and low sulfur content of the molten iron allow it to be directly used in the steelmaking process, facilitating the direct utilization of the product.

[0019] In the above-mentioned resource recovery method, preferably, the flue gas generated in step (3) is returned to the drying process. Returning the flue gas to the drying process can serve two purposes: firstly, it provides heat for the drying process and reduces energy consumption; secondly, it utilizes the reducing gases in the flue gas to improve the utilization rate of the reducing agent.

[0020] The main chemical reaction equations involved in the heating and roasting process of this invention are as follows:

[0021] FeS2+1.25Fe2(SO4)3=3.5FeO+5.75SO2(g);

[0022] Fe2(SO4)3=Fe2O3+3SO2(g)+1.5O2(g);

[0023] 1.5Fe2(SO4)3=Fe3O4+4.5SO2(g)+2.5O2(g);

[0024] Fe2(SO4)3=2FeO+3SO2(g)+2O2(g).

[0025] The reduction mechanism of iron oxide using hydrogen in this invention is as follows:

[0026] 3Fe2O3+H2(g)=2Fe3O4+H2O(g);

[0027] Fe3O4 + H2(g) = 3FeO + H2O(g);

[0028] FeO + H2(g) = Fe + H2O(g).

[0029] Compared with the prior art, the advantages of the present invention are as follows:

[0030] 1. The resource recovery method for iron recovery from high-pressure leaching residue of laterite nickel ore of the present invention combines a heating roasting process with a heating smelting process to process the high-pressure leaching residue of laterite nickel ore, thereby realizing the resource recovery and high-value utilization of the residue. This achieves efficient recovery and utilization of iron from the residue, avoids environmental pollution caused by its stockpiling, alleviates the supply and demand contradiction of iron resources in China, and allows the molten iron obtained to be directly used in the steelmaking process, thus promoting the development of my country's steel industry.

[0031] 2. The resource recovery method for recovering iron from high-pressure leaching residue of laterite nickel ore of the present invention innovatively adopts the method of mixing roasting material with pyrite and then heating and roasting. The synergistic effect of the two can effectively reduce the sulfur element in the product, which is conducive to the resource utilization of the product. It can also increase the SO2 concentration in the flue gas, so that the sulfur element removed in this step can also be fully utilized, and the full recovery and utilization of resources can be achieved. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a process flow diagram of the resource recovery method for recovering iron from high-pressure leaching residue of laterite nickel ore according to the present invention. Detailed Implementation

[0034] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0035] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0036] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0037] Example 1:

[0038] like Figure 1 As shown, a resource recovery method for recovering iron from high-pressure leaching residue of laterite nickel ore includes the following steps:

[0039] (1) The high-pressure leaching residue of laterite nickel ore and the binder bentonite were mixed and stirred in a mass ratio of 85:15 and then pelletized by pelletizing process; the pellets were dried at 120℃ for 2 hours to obtain dried pellets.

[0040] (2) The dried pellets and pyrite are mixed at a mass ratio of 90:10 and roasted under an oxygen atmosphere. The oxygen supply rate is 35 m³ / ton of dried pellets under standard atmospheric pressure. 3 The roasting temperature is 900℃, and after roasting for 2.5 hours, roasting material and flue gas are obtained. The flue gas is then processed into sulfuric acid through an acid production process.

[0041] (3) The calcining material, 8% flux by weight of the calcining material and 5% carbon by weight of the calcining material are smelted at 1500℃ for 3.5h to obtain molten iron, slag and flue gas. The flue gas is returned to the drying process and the slag is used as cement clinker.

[0042] In this embodiment, the main components of the high-pressure leaching residue of laterite nickel ore are 45.5% iron, 1.3% chromium, 0.85% aluminum, 0.33% magnesium, and 1.9% sulfur, with sulfur mainly existing in the form of sulfate. The sulfur content in the roasted material obtained after step (2) is 0.2%, and the volume concentration of sulfur dioxide in the flue gas is 4.88%, which can be directly used for acid production. The elemental iron content in the molten iron obtained after step (3) is 95.10%, the sulfur content is 0.020%, and the iron recovery rate is 95.43%, which can be directly used in the steelmaking process.

[0043] Example 2:

[0044] like Figure 1 As shown, a resource recovery method for recovering iron from high-pressure leaching residue of laterite nickel ore includes the following steps:

[0045] (1) The high-pressure leaching residue of laterite nickel ore and the binder bentonite were mixed and stirred in a mass ratio of 85:15 and then pelletized by pelletizing process; the pellets were dried at 120℃ for 2 hours to obtain dried pellets.

[0046] (2) The dried pellets and pyrite are mixed at a mass ratio of 95:5 and roasted under an oxygen atmosphere. The oxygen flow rate is 35 m³ / ton of dried pellets under standard atmospheric pressure. 3 The roasting temperature is 1000℃, and after roasting for 2.5 hours, roasting material and flue gas are obtained. The flue gas is then processed into sulfuric acid through an acid production process.

[0047] (3) The calcining material, 8% flux by weight of the calcining material and 5% carbon by weight of the calcining material are smelted at 1500℃ for 3.5h to obtain molten iron, slag and flue gas. The flue gas is returned to the drying process and the slag is used as cement clinker.

[0048] In this embodiment, the main components of the high-pressure leaching residue of laterite nickel ore are 45.5% iron, 1.3% chromium, 0.85% aluminum, 0.33% magnesium, and 1.9% sulfur, with sulfur mainly existing in the form of sulfate. The sulfur content in the roasted material obtained after step (2) is 0.18%, and the volume concentration of sulfur dioxide in the flue gas is 4.01%, which can be directly used for acid production. The elemental iron content in the molten iron obtained after step (3) is 96.89%, the sulfur content is 0.017%, and the iron recovery rate is 96.53%, which can be directly used in the steelmaking process.

[0049] Example 3:

[0050] like Figure 1 As shown, a resource recovery method for recovering iron from high-pressure leaching residue of laterite nickel ore includes the following steps:

[0051] (1) The high-pressure leaching residue of laterite nickel ore and the binder bentonite were mixed and stirred in a mass ratio of 88:12 and then pelletized by pelletizing process; the pellets were dried at 120℃ for 3 hours to obtain dried pellets.

[0052] (2) The dried pellets and pyrite are mixed at a mass ratio of 92:8 and roasted under an oxygen atmosphere. The oxygen flow rate is 30 m³ / ton of dried pellets under standard atmospheric pressure. 3 The roasting temperature is 800℃, and after roasting for 3 hours, roasting material and flue gas are obtained. The flue gas is then processed into sulfuric acid through an acid production process.

[0053] (3) The calcining material, 8% flux by weight of the calcining material and 5% carbon by weight of the calcining material are smelted at 1450℃ for 3 hours to obtain molten iron, slag and flue gas. The flue gas is returned to the drying process and the slag is used as cement clinker.

[0054] In this embodiment, the main components of the high-pressure leaching residue of laterite nickel ore are 45.5% iron, 1.3% chromium, 0.85% aluminum, 0.33% magnesium, and 1.9% sulfur, with sulfur mainly existing in the form of sulfate. The sulfur content in the roasted material obtained after step (2) is 0.19%, and the volume concentration of sulfur dioxide in the flue gas is 4.22%, which can be directly used for acid production. The elemental iron content in the molten iron obtained after step (3) is 95.89%, the sulfur content is 0.020%, and the iron recovery rate is 95.51%, which can be directly used in the steelmaking process.

[0055] Comparative Example 1:

[0056] A resource recovery method for recovering iron from high-pressure leaching residue of laterite nickel ore includes the following steps:

[0057] (1) The high-pressure leaching residue of laterite nickel ore and the binder bentonite were mixed and stirred in a mass ratio of 85:15 and then pelletized by pelletizing process; the pellets were dried at 120℃ for 2 hours to obtain dried pellets.

[0058] (2) Dry pellets, 8% flux by weight of dry pellets and 5% carbon by weight of dry pellets are smelted at 1500℃ for 3.5h to obtain molten iron, slag and flue gas. The flue gas is returned to the drying process and the slag is used as cement clinker.

[0059] In this comparative example, the main components of the high-pressure leaching residue of laterite nickel ore were 45.5% iron, 1.3% chromium, 0.85% aluminum, 0.33% magnesium, and 1.9% sulfur, with sulfur mainly existing in the form of sulfate. After step (3), the molten iron obtained had an elemental iron content of 91.22% and a sulfur content of 0.10%, with an iron recovery rate of 89.21%, making it unsuitable for direct use in the steelmaking process.

[0060] Comparative Example 2:

[0061] A resource recovery method for recovering iron from high-pressure leaching residue of laterite nickel ore includes the following steps:

[0062] (1) The high-pressure leaching residue of laterite nickel ore and the binder bentonite were mixed and stirred in a mass ratio of 85:15 and then pelletized by pelletizing process; the pellets were dried at 120℃ for 2 hours to obtain dried pellets.

[0063] (2) The dried pellets are heated and roasted in an oxygen atmosphere, with an oxygen flow rate of 35 m³ / ton of dried pellets at standard atmospheric pressure. 3 The roasting temperature was 900℃, and after roasting for 2.5 hours, roasted material and flue gas were obtained.

[0064] (3) The calcining material, 8% flux by weight of the calcining material and 5% carbon by weight of the calcining material are smelted at 1500℃ for 3.5h to obtain iron, smelting slag and flue gas. The flue gas is returned to the drying process and the smelting slag is used as cement clinker.

[0065] In this comparative example, the main components of the high-pressure leaching residue of laterite nickel ore are 45.5% iron, 1.3% chromium, 0.85% aluminum, 0.33% magnesium, and 1.9% sulfur, with sulfur mainly existing in the form of sulfate. The sulfur content in the roasted material obtained after step (2) is 0.29%, and the volume concentration of sulfur dioxide in the flue gas is 2.03%. The content of elemental iron in the molten iron obtained after step (3) is 94.65%, the sulfur content is 0.073%, the iron recovery rate is 90.11%, and the sulfur content is relatively high, making it unsuitable for direct use in the steelmaking process.

Claims

1. A resource recovery method for recovering iron from high-pressure leaching residue of laterite nickel ore, characterized in that, Includes the following steps: (1) The high-pressure leaching residue of laterite nickel ore and the binder are mixed and stirred, and then pellets are obtained by pelletizing process and dried. The high-pressure leaching residue of laterite nickel ore contains 40-60% iron, 0.8-1.5% chromium, 0.5-1.5% aluminum, 0.1-0.5% magnesium and 1-2.5% sulfur by mass, and the sulfur mainly exists in the form of sulfate. (2) The dried pellets are mixed with pyrite and heated and roasted in an oxygen atmosphere to obtain roasting material and flue gas. The flue gas is then processed to obtain sulfuric acid. (3) The roasting material, flux and reducing agent are mixed and then heated and smelted to obtain molten iron, slag and flue gas; The mass ratio of the dried pellets to pyrite is controlled to be (90-95):(5-10); The volume concentration of SO2 in the flue gas obtained in step (2) is greater than 3.5%, and the mass content of sulfur in the calcined material is less than 0.25%. The molten iron contains more than 95% elemental iron and less than 0.04% sulfur.

2. The resource recycling method according to claim 1, characterized in that, The binder includes one or more of bentonite, hydrated lime and quicklime, and the mass ratio of the high-pressure leaching residue of laterite nickel ore to the binder is (80-90):(10-20); the drying temperature is controlled at 100-150℃ and the drying time is 1-3h.

3. The resource recycling method according to claim 1, characterized in that, During heating and roasting, the roasting temperature should be controlled at 800-1000℃ and the roasting time should be 1-4 hours.

4. The resource recycling method according to claim 1, characterized in that, Oxygen is introduced during heating and roasting, at a rate of 30-100 mg / ton of dried pellets per standard atmosphere. 3 .

5. The resource recycling method according to any one of claims 1-4, characterized in that, The fluxing agent includes one or more of limestone, quicklime, and hydrated lime, and the amount of fluxing agent added is 5-10% of the mass of the calcined material.

6. The resource recycling method according to any one of claims 1-4, characterized in that, The reducing agent includes a solid reducing agent and a gaseous reducing agent. The solid reducing agent includes one or more of anthracite, bituminous coal, and coke. The gaseous reducing agent includes one or more of hydrogen, carbon monoxide, water gas, and natural gas. The amount of reducing agent added is calculated separately for solid reducing agents, and the amount added is 4-8% of the mass of the roasted material. The amount of reducing agent added is calculated separately for gaseous reducing agents, and the rate of introduction of reducing agent is 150-300 m³ per ton of roasted material under standard atmospheric pressure. 3 .

7. The resource recycling method according to any one of claims 1-4, characterized in that, When heating and melting, control the melting temperature to 1400-1550℃ and the melting time to 2-4 hours.

Images