A comprehensive utilization method for all components of the leaching residue in the high-pressure acid leaching process of laterite nickel ore

Abstract

The invention discloses a comprehensive utilization method for all components of the leaching residue in the high-pressure acid leaching process of laterite nickel ore, belonging to the technical field of solid waste resource utilization. Granulating and sintering the iron-containing slag in the high-pressure acid leaching process of laterite nickel ore with raw materials including coke fines, fluxes and returned ore to obtain sintered ore and sulfur dioxide flue gas; using the sulfur dioxide to prepare sulfuric acid and returning it to the high-pressure acid leaching process of laterite nickel ore; smelting the sintered ore with coke and slag regulators in a blast furnace to obtain hot metal and molten slag; quenching the molten slag to obtain granulated molten slag; after part of the granulated molten slag is ground, it is mixed with granulated molten slag and auxiliary materials including alkali activators and neutralization tailings in the high-pressure acid leaching process of laterite nickel ore as backfill materials. This method can achieve low-consumption, high-efficiency and large-scale comprehensive utilization of all components of the leaching residue in the high-pressure acid leaching process of laterite nickel ore, complete 100% resource utilization of the slag, and has considerable potential for industrial promotion.

Description

Technical Field

[0001] The present invention relates to a method for comprehensive utilization of all components of leaching residue in the high-pressure acid leaching process of laterite nickel ore, belonging to the technical field of metallurgy and comprehensive utilization of industrial solid waste. Background Art

[0002] Nickel is an important industrial metal and is widely used in fields such as stainless steel, nickel-based alloys, and ternary cathode materials. With the increasing depletion of sulfide nickel ore resources, laterite nickel ore has gradually become the main nickel extraction ore source. Laterite nickel ore is usually divided into limonite layer, clay layer, and saprolite layer. Among them, the limonite layer is suitable for wet treatment, accounting for 65% - 75%; the saprolite layer is suitable for pyrometallurgical treatment, accounting for 15% - 25%; the clay layer accounts for about 10% and can be treated by wet or pyrometallurgical methods. In hydrometallurgy, the high-pressure acid leaching (HPAL) technology has become the mainstream choice due to its advantages such as low carbon emissions, low energy consumption, high comprehensive recovery rate of nickel and cobalt metals, and mature technology. However, for every ton of metal nickel product produced, about 120 tons of leaching residue will be generated, including acid leaching residue, iron and aluminum removal residue, and neutralization tailings. Among them, the acid leaching residue with the largest amount of slag and the iron and aluminum removal residue with the second largest amount of slag contain rich iron and a large amount of components such as silicon, aluminum, calcium, magnesium, and sulfur, and have extremely high resource recovery and utilization value, while the neutralization tailings mainly composed of calcium sulfate salts have relatively low recovery and utilization value. At present, for the sake of the effectiveness of treatment methods and economic considerations, most enterprises mainly directly stack the three types of residues, which not only causes serious waste of resources, but also heavy metal ions such as chromium, nickel, and cobalt in the slag may pose serious safety hazards to the ecological environment. Therefore, the harmless and resource-based treatment of HPAL slag is extremely urgent.

[0003] At present, there have been extensive reports on the resource utilization of the leaching residue from the high-pressure acid leaching process of laterite nickel ore. Chinese Patent Application (CN116875759A) discloses a resource recovery method for recovering iron from the high-pressure leaching residue of laterite nickel ore. In this method, the high-pressure leaching residue of laterite nickel ore and a binder are mixed and stirred, and then pellets are obtained through a pelletizing process, and the dried pellets are obtained after drying treatment; the dried pellets are mixed with pyrite and heated and roasted in an oxygen atmosphere to obtain roasted material and flue gas, and sulfuric acid is obtained from the flue gas through an acid-making process; the roasted material, flux, and reducing agent are mixed and then heated and smelted to obtain molten iron, smelting slag, and flue gas. Chinese Patent Application (CN119265405A) discloses a recovery method for the leaching residue of laterite nickel ore. In this method, the leaching residue of laterite nickel ore is roasted in the presence of a first reducing agent to obtain roasted ore and sulfur-containing tail gas; in the presence of a second reducing agent, the roasted ore obtained above is smelted to obtain molten iron, smelting slag, and coal gas. Chinese Patent Application (CN118326154A) discloses a comprehensive recovery and utilization method for all components of the high-pressure acid leaching residue of laterite nickel ore. In this method, the high-pressure acid leaching residue of laterite nickel ore, a binder, and a reducing agent are mixed to form material balls; the material balls are dried and then externally doped with limestone and calcined to obtain calcined material; the calcined material is smelted to obtain molten iron and hot molten slag; the molten iron is made into iron ingots, and the hot molten slag is successively subjected to conditioning, melting homogenization, forming, crystallization, and annealing to prepare microcrystalline glass. Chinese Patent (CN117403057B) discloses a treatment method and active material for the acid leaching residue of laterite nickel ore. In this method, the acid leaching residue of laterite nickel ore, an adjusting material, a fluxing material, and a reducing agent are mixed and pressed to obtain a preform; the preform is roasted to obtain hot roasted slag and hot flue gas, and the hot flue gas is used for acid making; the hot roasted slag is subjected to magnetic separation to obtain refined iron material and tail slag; the tail slag, active material, and activating material are mixed and ground to obtain an active material.

[0004] In the technical route of smelting and recovering iron, the existing publicly available technologies mainly use oxidative or reductive roasting to pretreat the acid leaching residue of laterite nickel ore. However, the roasted materials obtained by such technical means have low mechanical strength and poor metallurgical properties and cannot be used as the furnace charge for a large-scale, mature, and reliable blast furnace ironmaking process. In terms of sulfur dioxide recovery, due to the large flue gas flow and low concentration in the conventional roasting process, it is often necessary to introduce a sulfur source into the raw materials or re-enrich the sulfur in the flue gas to meet the conditions for acid making, and the overall difficulty of the acid-making recovery process is great. In the recovery of chemical components such as calcium, silicon, aluminum, and magnesium, the preparation of microcrystalline glass requires multi-stage high-temperature treatment and is limited in large-scale application. In the method of directly preparing active materials from magnetic separation tailings, the magnetic separation tailings have not been subjected to melting and quenching and have no direct activity, and an external active material is required as the active source.

[0005] In summary, it is of great significance to develop a method for large-scale, efficient, and comprehensive utilization of all components of the leaching residue from the high-pressure acid leaching process of laterite nickel ore. Summary of the Invention

[0006] Aiming at the technical problems existing in the resource utilization process of the leaching residue in the high-pressure acid leaching process of laterite nickel ore in the prior art, the main purpose of the present invention is to provide a method capable of realizing large-scale and efficient comprehensive utilization of all components of the leaching residue (including acid leaching residue, iron and aluminum removal residue, neutralization tailing residue, etc.) in the high-pressure acid leaching process of laterite nickel ore, so as to solve the problems of low efficiency, high consumption, low comprehensive recovery rate and difficulty in large-scale industrial application in the treatment of the leaching residue in the high-pressure acid leaching process of laterite nickel ore in the prior art.

[0007] To achieve the above technical purpose, the present invention provides a method for comprehensive utilization of all components of the leaching residue in the high-pressure acid leaching process of laterite nickel ore, and the method includes the following steps:

[0008] (1) Granulating and sintering the iron-containing slag in the high-pressure acid leaching process of laterite nickel ore with raw materials including coke powder, flux and return ore to obtain sintered ore and sulfur dioxide flue gas;

[0009] (2) Using the sulfur dioxide flue gas to prepare sulfuric acid, and returning the obtained sulfuric acid to the high-pressure acid leaching process of laterite nickel ore;

[0010] (3) Smelting the sintered ore with coke and slag conditioner in a blast furnace to obtain hot metal and molten slag;

[0011] The slag conditioner is used to control the CaO / SiO2 in the molten slag to be 1.0 - 1.5, Al2O3 / SiO2 to be 0.1 - 0.6, the content of Al2O3 to be 8 - 15 wt%, the content of MgO to be 5 - 12 wt%, the content of Fe2O3 to be less than 5 wt%, and the S content to be less than 1.5 wt%;

[0012] The slag conditioner includes at least one of limestone, silica, dolomite and bauxite;

[0013] (4) Cooling and quenching the molten slag to obtain granulated molten slag; Grinding part of the granulated molten slag to obtain granulated molten slag powder;

[0014] (5) Mixing the granulated molten slag powder, the granulated molten slag with auxiliary materials including an alkali activator and the neutralization tailing residue in the high-pressure acid leaching process of laterite nickel ore as backfill.

[0015] The key to the technical solution of the present invention is to realize the comprehensive resource utilization of three kinds of waste slags, namely, acid leaching slag, iron-removing aluminum slag, and neutralization tailings, produced by the high-pressure acid leaching process of laterite nickel ore. Based on the composition characteristics of the three kinds of waste slags, targeted differentiated treatment is carried out, and a three-stage conversion process path of "slag element recovery-slag activity regulation-tailings harmless backfilling" is proposed. For acid leaching slag and iron-removing aluminum slag, which contain rich iron and a large amount of silicon, aluminum, calcium, magnesium, sulfur and other components, the sulfur and iron elements therein can be efficiently recovered through the "sintering-blast furnace smelting" process route, and the composition of blast furnace slag is precisely adjusted, and cold quenching and grinding processes are combined to obtain granulated slag aggregate and high-activity granulated slag powder, giving the slag unique recycling characteristics. On this basis, granulated slag powder, granulated slag and neutralization tailings are used as the main components to construct a low-cost, high-performance backfill body, realizing "slag treatment with slag" and 100% resource utilization of slag.

[0016] The present invention uses a slag adjusting agent to adjust the composition of blast furnace smelting slag, for example, adjusting the basicity (CaO / SiO2) to 1.0-1.5, the activation coefficient (Al2O3 / SiO2) to 0.1-0.6, the Al2O3 content to 8-15wt%, the MgO content to 5-12wt%, the Fe2O3 content to less than 5wt%, and the S content to less than 1.5wt%. If the alkalinity is too strong, it is easy to cause the gel reaction to be too fast, resulting in uncontrolled early coagulation and uneven gel structure, which in turn affects the later strength and durability. If the alkalinity is too low, it may be insufficiently activated. If the activity coefficient is too high, it will disrupt the ideal ratio of aluminosilicate gel, affecting mechanical properties and chemical corrosion resistance. If the activity coefficient is too low, it will be unfavorable for colloid generation. If the Al2O3 content is too high, it may cause excessive aluminum content in the gel, forming an unstable phase and weakening durability. If the content is too low, the gelation reaction activity will be reduced. If the MgO content is too high, it is easy to promote the formation of expansive phases, increasing the risk of volume instability. If the MgO content is too low, it may lead to insufficient reaction activity. If the Fe2O3 content is too high, it will promote the formation of impurities, interfere with the formation of favorable gel structures, and reduce overall reactivity. If the S content is too high, it is easy to form excessive sulfates, inducing expansion, cracking and reduced durability. In summary, the present invention is conducive to obtaining backfill with better performance by regulating the slag phase.

[0017] As a preferred solution, the iron-containing slag from the high-pressure acid leaching process of laterite nickel ore includes high-pressure acid leaching slag from laterite nickel ore and / or iron- and aluminum-removing slag from neutralization of high-pressure acid leaching liquid from laterite nickel ore.

[0018] As a preferred embodiment, the raw materials comprise the following components by mass percentage: 50 - 75% of iron-containing slag from the high-pressure acid leaching process of laterite nickel ore, 4 - 9% of coke powder, 5 - 15% of flux, and 15 - 30% of returned ore. Among them, each raw material component is measured by dry basis mass. The appropriate proportion composition helps to optimize the sintering process, ensure the production and quality of sintered ore, and is beneficial to the smooth operation of the blast furnace. The flux is, for example, quicklime.

[0019] As a preferred embodiment, the sintering temperature is 1200 - 1400 °C.

[0020] In the present invention, the iron-containing slag from the high-pressure acid leaching process of laterite nickel ore is used as the iron raw material. By combining sintering auxiliary materials such as coke powder, flux, and returned ore, and at an appropriate sintering temperature, sintered ore with relatively high quality can be obtained. For example, the total iron (TFe) content of the sintered ore is greater than 52 wt%, the drum strength (TI) is greater than 60%, the reducibility (RI) is greater than 65%, and the sulfur content is less than 0.2 wt%. The obtained sintered ore is completely applicable to the blast furnace ironmaking process. Sufficient total iron content, good mechanical strength, and reducibility are crucial for the energy efficiency and operation stability of the blast furnace ironmaking process. However, too high a sulfur content in the sintered ore will directly increase the total sulfur content entering the furnace, resulting in an increase in the desulfurization load and deterioration of the hot metal quality.

[0021] As a preferred embodiment, the sulfur dioxide flue gas is the flue gas in the 50% - 100% area along the traveling direction of the sintering machine trolley, and its average sulfur dioxide concentration is higher than 1 vol%. During the sintering process, the sulfur in the iron-containing slag from the high-pressure acid leaching process of laterite nickel ore is converted into sulfur dioxide and moves downward with the airflow and is absorbed by the moisture and flux in the lower sintering mixture. When the over-wet zone reaches the bottom and gradually disappears, the sulfur dioxide is desorbed and concentratedly released. Therefore, the appropriate flue gas area position is the key to obtaining high-quality sulfur dioxide. A sulfur dioxide concentration above 1 vol% is beneficial to maintaining self-thermal balance in the sulfuric acid production process (such as the Concat process).

[0022] As a preferred embodiment, the particle size range of the granulated slag is 1 - 10 mm, and the vitreous body content is higher than 85 wt%. The granulated slag mainly serves as the aggregate of the backfill material, with a high vitreous body content and a particle size range of 1 - 10 mm. Over-large particles will reduce its specific surface area and the reaction interface with the alkali-activated cementitious system, thereby affecting the formation of the gel phase and the bonding between the aggregate and the colloid. This will lead to a decrease in the material density and an increase in the porosity, further weakening the early strength and durability, and may also affect the fluidity and overall uniformity of the construction. Further preferably, the particle size range of the granulated slag is 1 - 5 mm. If the vitreous body content is too low and the crystal phase proportion increases, it will directly result in low activity of the subsequent granulated slag powder, affecting the denseness and durability of the microstructure of the filler.

[0023] As a preferred solution, the specific surface area of the granulated slag powder is 400 - 700 kg / m 2 , the particle size D50 of the particles is 8 - 15 μm, D90 is less than 45 μm, and the moisture content is less than 1 wt%. The granulated slag powder mainly serves as a cementitious active component. If its specific surface area is too low, the reaction interface is insufficient and the activity decreases; if its specific surface area is too high, it may increase the water demand and affect the construction performance. Coarser particles (D50 greater than 15 μm or D90 exceeding 45 μm) will lead to uneven reactions, reducing the early reaction rate and the overall cementing effect. Too high a moisture content is likely to cause pre-hydration, affecting the storage stability and the control of the alkali activation reaction. The granulated slag powder is obtained by grinding granulated slag, and the grinding process adopts any one or a combination of ball milling, high-pressure roller milling, and vertical milling.

[0024] As a preferred solution, the alkali activator includes at least one of NaOH, KOH, Na2CO3, and Na2SiO3. These alkali activators are conventional reagents in the industry.

[0025] As a preferred solution, the backfill contains the following components by mass percentage: 25 - 50% of granulated slag powder; 3 - 10% of alkali activator; 20 - 40% of granulated slag; 10 - 25% of the neutralization tailings of the high-pressure acid leaching process of laterite nickel ore. The neutralization tailings contain a large amount of calcium sulfate salt components, which can act together with the alkali activator (such as NaOH or sodium silicate) to promote the hydration reaction of the cementitious material, accelerate the formation of hydration products such as ettringite, and thus improve the early strength of the material.

[0026] As a preferred solution, the backfill contains no more than 15 wt% of admixtures.

[0027] As a preferred solution, the admixtures include at least one of fly ash, metakaolin, and lime. The addition of an appropriate amount of admixtures is beneficial to reducing the defects of a single cementitious phase and further enhancing the overall stability of the backfill.

[0028] As a preferred solution, the backfill is mixed with water according to a water-binder ratio of 0.25 - 0.4, and then filled and cured. Under standard curing conditions, the 7-day and 28-day compressive strengths of the backfill are higher than 3 MPa and 8 MPa respectively.

[0029] Compared with the prior art, the beneficial technical effects brought by the technical solution of the present invention:

[0030] 1. The present invention specifically sinters and agglomerates the acid leaching residue with a high iron content and the iron and aluminum removal residue in the residue of the laterite nickel ore high-pressure acid leaching process to obtain high-quality furnace materials suitable for blast furnace ironmaking. Combining the sintering process principle and the characteristics of centralized emission of sintering flue gas, it realizes the deep separation of iron and sulfur elements, and at the same time completes the enrichment of sulfur elements, creating conditions for low-cost self-thermal balance sulfuric acid production. The sulfuric acid is recycled for the leaching process of the laterite nickel ore high-pressure acid leaching process, significantly reducing the external purchase cost of sulfuric acid raw materials for the high-pressure acid leaching process. In addition, the waste heat generated in the three major links of sintering, sulfuric acid production, and blast furnace smelting can be used to prepare steam for the slurry preheating process of the laterite nickel ore high-pressure acid leaching process, significantly reducing the demand for additional heat in this link, thereby reducing the energy consumption cost.

[0031] 2. The present invention makes full use of the characteristics of the mineral compositions of the three waste residues, namely, the acid leaching residue, the iron and aluminum removal residue, and the neutralization tail residue, generated in the laterite nickel ore high-pressure acid leaching process, and realizes the recovery of useful elements and mineral transformation in various waste residues based on a special process path, designing a unique backfill material formula. By precisely adjusting the composition of blast furnace slag, granulated slag with a high vitreous content is prepared by air cooling, and further ground to obtain granulated slag powder. The granulated slag has a coarse particle size and low activity, while the granulated slag powder has a fine particle size and high activity. With the reasonable combination of slag powder and slag, their different reaction rates (rapid early reaction of slag powder and long-term slow release effect of slag) and physical properties (slag powder improving density and slag optimizing fluidity) are complementary, which helps to provide balanced performance improvement for the backfill material at different stages (early and long-term), and at the same time optimize the workability and construction performance of the backfill material.

[0032] 3. The process system of the present invention has a high degree of integration, and can achieve the full-chain coordination of high-pressure acid leaching - sintering - smelting - preparation of cementitious materials, effectively integrating the acid leaching residue of the laterite nickel ore high-pressure acid leaching process itself and the additional waste generated in the process of its comprehensive recycling, completing "element recovery" and "treating slag with slag", realizing 100% resource utilization of slag, obtaining economic benefits and simultaneously eliminating the negative impact of slag stacking or landfill treatment on the environment, reflecting the concept of green development.

[0033] In summary, the technology of the present invention has the potential for industrial promotion, and will form a significant competitive advantage especially in the field of large-scale treatment of the acid leaching residue of the laterite nickel ore high-pressure acid leaching process. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is the process flow diagram of the comprehensive utilization method of all components of the acid leaching residue of the laterite nickel ore high-pressure acid leaching process of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The present invention will be further described in detail below in combination with preferred embodiments, rather than limiting the protection scope of the claims of the present invention.

[0036] Unless otherwise defined, all technical terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Example 1

[0037] The sintering raw material ratio is carried out by mass percentage (dry basis), with a fixed binary basicity of 1.6 and a granulation moisture of 17.5%. Among them, the mass ratios of laterite nickel ore high-pressure iron-containing slag (80wt% acid leaching residue + 20wt% iron-aluminum slag), coke powder, flux (quicklime), and returned ore (internally proportioned) are 58.2%, 8.0%, 10.7%, and 23.1% respectively. Subsequently, granulation is carried out and sintering and agglomeration are carried out in a sintering cup. At the same time, a flue gas analyzer is used to conduct on-line test and analysis of the flue gas. The final sintering time is 40.52 min. The indexes of the sintered ore obtained are as follows: total iron content (TFe) 52.2wt%, drum strength (TI) 62.7%, reduction degree (RI) 65.8%, and sulfur content 0.1wt%. The average concentration of sulfur dioxide in the flue gas from the 20th to 40th minute of sintering is 1.4 vol%, reaching the acid-making conditions of the wet process. The obtained sintered ore is mixed with coke and slag conditioner, smelted in a high-temperature box-type resistance furnace (about 1500 °C) and slag-iron separation is achieved (the slag and iron are self-stratified due to density differences). Subsequently, water quenching and cooling are carried out, and finally iron blocks and molten slag are obtained. The basicity of the molten slag (CaO / SiO2) is 1.2, the activation coefficient (Al2O3 / SiO2) is 0.55, the Al2O3 content is 14.4wt%, the MgO content is 8.3wt%, the Fe2O3 content is 1.1wt%, and the S content is 0.71wt%. Subsequently, it is subjected to roll crushing to obtain granulated molten slag, with a vitreous content of 91wt% and an average particle size of 4.8 mm. 50% of the granulated molten slag is ground by a ball mill to obtain granulated molten slag powder, with a specific surface area of 530 kg / m², a median particle size (D50) of 11.1 μm, a 90% particle size (D90) of 38.7 μm, and a moisture content of 0.32wt%. 35wt% of the granulated molten slag powder, 7wt% of fly ash, 35wt% of granulated molten slag, and 16wt% of neutralization tailings are uniformly mixed by a powerful mixer to obtain a dry mixture; at the same time, 7wt% of an alkali activator (50wt% NaOH + 50wt% Na2SiO3) is dissolved in water to obtain an alkali activator solution, and the water-binder ratio is controlled to be 0.35; finally, the alkali activator solution is slowly added to the dry mixture and stirred evenly again by a powerful stirrer to obtain a backfill. The backfill is poured into a mold for molding and cured for 7 days and 28 days under standard curing conditions (temperature 20 ± 2 °C, relative humidity above 95%), and its compressive strength is tested. The main components and compositions of the acid leaching residue, iron-aluminum slag, and neutralization tailings are shown in Table 1.

[0038] In this embodiment, the obtained backfill material, under standard curing conditions, has 7-day and 28-day compressive strengths of 4.2 MPa and 13.9 MPa respectively, meeting the requirements of the mine backfill project. Example 2

[0039] The sintering raw material ratio is based on mass percentage (dry basis), with a fixed binary basicity of 1.6 and granulation moisture of 17.5%. Among them, the mass ratios of laterite nickel ore high-pressure iron-containing slag (80 wt% acid leaching residue + 20 wt% iron-aluminum slag), coke powder, flux (quicklime), and returned ore (internally proportioned) are 58.2%, 8.0%, 10.7%, and 23.1% respectively. Subsequently, granulation is carried out and sintering and agglomeration are performed in a sintering cup. At the same time, a flue gas analyzer is used for on-line testing and analysis of the flue gas. The final sintering time is 40.52 min. The indexes of the obtained sintered ore are as follows: total iron content (TFe) 52.2 wt%, drum strength (TI) 62.7%, reduction degree (RI) 65.8%, and sulfur content 0.1 wt%. The average concentration of sulfur dioxide in the flue gas from the 24th to 36th minute of sintering is 2.1 vol%, meeting the conditions for sulfuric acid production by the wet process. The obtained sintered ore is mixed with coke and slag conditioner, smelted in a high-temperature box-type resistance furnace (about 1500 °C) and slag-iron separation is achieved (the slag and iron are self-stratified due to density differences). Subsequently, water quenching and cooling are carried out, and finally iron blocks and molten slag are obtained. The basicity of the molten slag (CaO / SiO2) is 1.1, the activation coefficient (Al2O3 / SiO2) is 0.3, the Al2O3 content is 8.9 wt%, the MgO content is 6.6 wt%, the Fe2O3 content is 0.8 wt%, and the S content is 0.65 wt%. Subsequently, it is subjected to roll crushing to obtain granulated molten slag with a vitreous body content of 94 wt% and an average particle size of 3.3 mm. 40% of the granulated molten slag is ground by a ball mill to obtain granulated molten slag powder with a specific surface area of 610 kg / m², a median particle size (D50) of 8.9 μm, a 90% particle size (D90) of 33.4 μm, and a moisture content of 0.25 wt%. 26 wt% of the granulated molten slag powder, 13 wt% of fly ash, 37 wt% of granulated molten slag, and 19 wt% of neutralization tailings are dry-mixed evenly by a powerful mixer to obtain a dry mixture; at the same time, 5 wt% of an alkali activator (50 wt% NaOH + 50 wt% Na2SiO3) is dissolved in water to obtain an alkali activator solution, with the water-binder ratio controlled at 0.38; finally, the alkali activator solution is slowly added to the dry mixture and stirred evenly again by strong stirring to obtain backfill material. The backfill material is poured into a mold for molding and cured for 7 days and 28 days under standard curing conditions (temperature 20 ± 2 °C, relative humidity above 95%), and its compressive strength is tested. The main components and compositions of the acid leaching residue, iron-aluminum slag, and neutralization tailings are shown in Table 1.

[0040] In this embodiment, the obtained backfill material, under standard curing conditions, has 7-day and 28-day compressive strengths of 3.4 MPa and 15.7 MPa respectively, meeting the requirements of the mine backfill project.

[0041] Example 3

[0042] The proportion of sintering raw materials is carried out according to mass percentage (dry basis), with a fixed binary basicity of 1.6 and granulation moisture of 17.5%. Among them, the mass ratios of laterite nickel ore high-pressure iron-containing slag (80wt% acid leaching residue + 20wt% iron-aluminum slag), coke powder, flux (quicklime), and return ore (internally proportioned) are 58.2%, 8.0%, 10.7%, and 23.1% respectively. Subsequently, granulation is carried out and sintering and agglomeration are carried out in a sintering cup. At the same time, a flue gas analyzer is used to conduct on-line test and analysis of the flue gas. The final sintering time is 40.52 min. The indexes of the obtained sintered ore are as follows: total iron content (TFe) 52.2wt%, drum strength (TI) 62.7%, reducibility (RI) 65.8%, and sulfur content 0.1wt%. The average concentration of sulfur dioxide in the flue gas from the 26th to 34th minute of sintering is 3.8vol%, reaching the acid-making conditions of the wet process. The obtained sintered ore is mixed with coke and slag conditioner, smelted in a high-temperature box-type resistance furnace (about 1500°C) and slag-iron separation is achieved (the slag and iron are self-stratified due to density differences). Subsequently, water quenching and cooling are carried out, and finally iron blocks and molten slag are obtained. The basicity of the molten slag (CaO / SiO2) is 1.3, the activation coefficient (Al2O3 / SiO2) is 0.4, the Al2O3 content is 11.8wt%, the MgO content is 11.5wt%, the Fe2O3 content is 1.2wt%, and the S content is 0.82wt%. Subsequently, it is subjected to roll crushing to obtain granulated molten slag, with a vitreous content of 89wt% and an average particle size of 6.5 mm. 70% of the granulated molten slag is ground by a ball mill to obtain granulated molten slag powder, with a specific surface area of 450 kg / m², a median particle size (D50) of 13.4 μm, a 90% particle size (D90) of 42.7 μm, and a moisture content of 0.27wt%. 43.5wt% of the granulated molten slag powder, 2wt% of fly ash, 21.5wt% of granulated molten slag, and 24wt% of neutralization tailings are dry-mixed evenly by a powerful mixer to obtain a dry mixture; at the same time, 9wt% of an alkali activator (50wt% NaOH + 50wt% Na2SiO3) is dissolved in water to obtain an alkali activator solution, and the water-binder ratio is controlled to be 0.31; finally, the alkali activator solution is slowly added to the dry mixture and stirred evenly again by strong stirring to obtain a backfill material. The backfill material is poured into a mold for molding and cured for 7 days and 28 days under standard curing conditions (temperature 20±2°C, relative humidity above 95%), and its compressive strength is tested. The main components and compositions of the acid leaching residue, iron-aluminum slag, and neutralization tailings are shown in Table 1.

[0043] In this example, the 7-day and 28-day compressive strengths of the obtained backfill material under standard curing conditions are 5.1 MPa and 11.3 MPa respectively, meeting the requirements of the mine backfill project.

[0044] Comparative Example 1

[0045] The sintering raw material ratio is based on mass percentage (dry basis), with a defined binary basicity of 1.6 and granulation moisture of 17.5. Among them, the mass ratios of laterite nickel ore high-pressure iron-containing slag (80wt% acid leaching residue + 20wt% iron-aluminum slag), coke powder, flux (quicklime), and return ore (internally matched) are 58.2%, 8.0%, 10.7%, and 23.1% respectively. Subsequently, granulation is carried out and sintering and agglomeration are carried out in a sintering cup. At the same time, a flue gas analyzer is used to conduct on-line test analysis of the flue gas. The final sintering time is 40.52 min. The indexes of the obtained sintered ore are as follows: total iron content (TFe) 52.2wt%, drum strength (TI) 62.7%, reduction degree (RI) 65.8%, and sulfur content 0.1wt%. The average concentration of sulfur dioxide in the flue gas during sintering from 0 to 40.52 min is 0.6vol%. The concentration is too low and the recovery is difficult. It is necessary to enrich, concentrate or supplement sulfur and heat, with high costs, and there is no effective direct self-thermal balance sulfuric acid production process. The main components and compositions of the acid leaching residue, iron-aluminum slag, and neutralization tail slag are shown in Table 1.

[0046] Comparative Example 2

[0047] The sintering raw material ratio is based on mass percentage (dry basis), with a defined binary basicity of 1.6 and granulation moisture of 17.5. Among them, the mass ratios of laterite nickel ore high-pressure iron-containing slag (80wt% acid leaching residue + 20wt% iron-aluminum slag), coke powder, flux (quicklime), and return ore (internally matched) are 58.2%, 8.0%, 10.7%, and 23.1% respectively. Subsequently, granulation is carried out and sintering and agglomeration are carried out in a sintering cup. At the same time, a flue gas analyzer is used to conduct on-line test analysis of the flue gas. The final sintering time is 40.52 min. The indexes of the obtained sintered ore are as follows: total iron content (TFe) 52.2wt%, drum strength (TI) 62.7%, reduction degree (RI) 65.8%, and sulfur content 0.1wt%. The average concentration of sulfur dioxide in the flue gas during sintering from 20 to 40 min is 1.4vol%, reaching the sulfuric acid production conditions of the wet process. The obtained sintered ore is mixed with coke and slag conditioner, smelted in a high-temperature box-type resistance furnace (about 1500°C) and slag-iron separation is achieved (the slag and iron are self-stratified due to density differences). Subsequently, water quenching and cooling are carried out, and finally iron blocks and molten slag are obtained. The slag basicity (CaO / SiO2) is 0.9, the activation coefficient (Al2O3 / SiO2) is 0.65, the Al2O3 content is 16.3wt%, the MgO content is 4.3wt%, the Fe2O3 content is 6.9wt%, and the S content is 0.67wt%. Subsequently, the same process route and formula as in Example 1 are used to obtain the backfill material. The backfill material is poured into a mold for molding and cured for 7 days and 28 days under standard curing conditions (temperature 20±2°C, relative humidity above 95%), and its compressive strength is tested. The main components and compositions of the acid leaching residue, iron-aluminum slag, and neutralization tail slag are shown in Table 1.

[0048] In this comparative example, the obtained backfill material, under standard curing conditions, had 7-day and 28-day compressive strengths of 1.7 MPa and 5.3 MPa respectively, which could not meet the requirements of the mine backfill project. Due to the too low slag basicity (CaO / SiO2), too high activation coefficient (Al2O3 / SiO2), and the excessive contents of Al2O3 (16.3 wt%) and Fe2O3 (6.9 wt%), as well as the insufficient content of MgO (4.3 wt%), the reaction system was unbalanced, inhibiting the formation of favorable colloidal phases, thus significantly reducing the activity of the cementitious material.

[0049] Comparative Example 3

[0050] The sintering raw material ratio was based on mass percentage (dry basis), with a defined binary basicity of 1.6 and granulation moisture of 17.5%. Among them, the mass ratios of laterite nickel ore high-pressure iron-containing slag (80 wt% acid leaching residue + 20 wt% iron-aluminum slag), coke powder, flux (quicklime), and returned ore (internally proportioned) were 58.2%, 8.0%, 10.7%, and 23.1% respectively. Subsequently, granulation was carried out and sintering agglomeration was performed in a sintering cup. At the same time, a flue gas analyzer was used to conduct on-line test analysis of the flue gas, and the final sintering time was 40.52 min. The indexes of the obtained sintered ore were as follows: total iron content (TFe) 52.2 wt%, drum strength (TI) 62.7%, reducibility (RI) 65.8%, and sulfur content 0.1 wt%. The average concentration of sulfur dioxide in the flue gas from the 20th to 40th minute of sintering was 1.4 vol%, meeting the conditions for sulfuric acid production by the wet process. The obtained sintered ore was mixed with coke and slag conditioner, smelted in a high-temperature box-type resistance furnace (about 1500 °C) and slag-iron separation was achieved (the slag and iron were self-stratified due to density differences), and then natural cooling was carried out, finally obtaining iron blocks and molten slag. The slag basicity (CaO / SiO2) was 1.1, the activation coefficient (Al2O3 / SiO2) was 0.3, the Al2O3 content was 8.9 wt%, the MgO content was 6.6 wt%, the Fe2O3 content was 0.8 wt%, and the S content was 0.53 wt%. Subsequently, it was subjected to roll crushing to obtain granulated molten slag, with a vitreous content of 54 wt% and an average particle size of 7.6 mm. 40 wt% of the granulated molten slag was ground by a ball mill to obtain granulated molten slag powder, with a specific surface area of 350 kg / m², a particle median diameter (D50) of 17.8 μm, a 90% particle size (D90) of 52.4 μm, and a moisture content of 0.45 wt%. Subsequently, the same process route and formula as in Example 2 were used to obtain the backfill material, and the backfill material was poured into a mold for molding, and cured for 7 days and 28 days under standard curing conditions (temperature 20 ± 2 °C, relative humidity above 95%), and its compressive strength was tested. The main components and compositions of the acid leaching residue, iron-aluminum slag, and neutralization tailings are shown in Table 1.

[0051] In this comparative example, the 7-day and 28-day compressive strengths of the obtained backfill material under standard curing conditions are 0.5 MPa and 4.8 MPa respectively, which cannot meet the requirements of the mine backfilling project. The higher the vitreous content of granulated blast furnace slag, the greater the potential activity. However, the low natural cooling rate leads to a decrease in the vitreous content, thereby affecting the activity of the slag. In addition, due to the overly coarse particles of granulated blast furnace slag powder, the hydration reaction of the coarse particles is slow, resulting in insufficient formation of hydration products and affecting the improvement of early strength. At the same time, the overly coarse granulated blast furnace slag powder may lead to an increase in the porosity of the cementitious material, reducing its compactness and thus affecting its long-term durability.

[0052] Comparative Example 4

[0053] The sintering raw material ratio is carried out by mass percentage (dry basis), with a fixed binary basicity of 1.6 and a granulation moisture of 17.5%. Among them, the mass ratios of laterite nickel ore high-pressure iron-containing slag (80wt% acid leaching residue + 20wt% iron-aluminum slag), coke powder, flux (quicklime), and return ore (internally proportioned) are 58.2%, 8.0%, 10.7%, and 23.1% respectively. Subsequently, granulation is carried out and sintering and agglomeration are carried out in a sintering cup. At the same time, a flue gas analyzer is used to conduct on-line test and analysis of the flue gas. The final sintering time is 40.52 min. The indexes of the obtained sintered ore are as follows: total iron content (TFe) 52.2wt%, drum strength (TI) 62.7%, reducibility (RI) 65.8%, and sulfur content 0.1wt%. The average concentration of sulfur dioxide in the flue gas from the 20th to 40th minute of sintering is 1.4vol%, reaching the acid-making conditions of the wet process. The obtained sintered ore is mixed with coke and slag conditioner, smelted in a high-temperature box-type resistance furnace (about 1500°C) and slag-iron separation is achieved. Subsequently, water quenching and cooling are carried out, and finally iron blocks and molten slag are obtained. The basicity of the molten slag (CaO / SiO2) is 1.3, the activation coefficient (Al2O3 / SiO2) is 0.4, the Al2O3 content is 11.8wt%, the MgO content is 11.5wt%, the Fe2O3 content is 1.2wt%, and the S content is 0.97wt%. Subsequently, it is subjected to roll crushing to obtain granulated molten slag, with a vitreous content of 88wt% and an average particle size of 6.5 mm. 100% of the granulated molten slag is ground by a ball mill to obtain granulated molten slag powder, with a specific surface area of 450 kg / m², a median particle size (D50) of 13.4 μm, a 90% particle size (D90) of 42.7 μm, and a moisture content of 0.27wt%. 65wt% of the granulated molten slag powder, 2wt% of fly ash, and 24wt% of neutralization tailings are dry-mixed by a powerful mixer to obtain a dry mixture; at the same time, 9wt% of an alkali activator (50wt% NaOH + 50wt% Na2SiO3) is dissolved in water to obtain an alkali activator solution, and the water-binder ratio is controlled at 0.37; finally, the alkali activator solution is slowly added to the dry mixture and stirred evenly again by a powerful stirrer to obtain a backfill material. The backfill material is poured into a mold for molding and cured for 7 days and 28 days under standard curing conditions (temperature 20±2°C, relative humidity above 95%), and its compressive strength is tested. The main components and compositions of the acid leaching residue, iron-aluminum slag, and neutralization tailings are shown in Table 1.

[0054] In this example, under the standard curing conditions, the 7-day and 28-day compressive strengths of the obtained backfill material are 3.9 MPa and 7.2 MPa respectively, which cannot meet the requirements of the mine backfilling project.

[0055] 。

Claims

1. A method for comprehensive utilization of all components of leached residues from high pressure acid leaching of laterite nickel ore, characterized in that: The following steps are involved: (1) pelletizing and sintering the iron-containing slag from high-pressure acid leaching of laterite nickel ore with raw materials including coke powder, flux and return ore to obtain sintered ore and sulfur dioxide flue gas; the iron-containing slag from high-pressure acid leaching of laterite nickel ore includes high-pressure acid leaching slag from laterite nickel ore and / or iron-removal aluminum slag from high-pressure acid leaching liquid of laterite nickel ore; (2) using the sulfur dioxide flue gas to prepare sulfuric acid, and returning the obtained sulfuric acid to the high-pressure acid leaching process of laterite nickel ore; (3) smelting the sintered ore, coke and slag conditioning agent in a blast furnace to obtain molten iron and slag; The slag adjusting agent is used to control the CaO / SiO2 in the slag to be 1.0-1.5, the Al2O3 / SiO2 to be 0.1-0.6, the Al2O3 content to be 8-15wt%, the MgO content to be 5-12wt%, the Fe2O3 content to be less than 5wt%, and the S content to be less than 1.5wt%; The slag conditioning agent includes at least one of limestone, silica, dolomite and ferrous bauxite; (4) quenching the slag to obtain granulated slag; grinding a portion of the granulated slag to obtain granulated slag powder; (5) The granulated slag powder, the granulated slag and auxiliary materials including an alkali activator and tailings from a high-pressure acid leaching process of laterite nickel ore are mixed as backfill.

2. The method for comprehensive utilization of all components of leached residues from a high-pressure acid leaching process of laterite nickel ore according to claim 1, characterized in that: The raw materials include the following components in percentage by weight: 50-75% iron-containing slag from high-pressure acid leaching of laterite nickel ore, 4-9% coke powder, 5-15% flux, and 15-30% return ore, wherein each raw material component is measured on a dry basis.

3. The method for comprehensive utilization of all components of leached residues from a high-pressure acid leaching process of laterite nickel ore according to claim 1 or 2, characterized in that: The sintering temperature is 1200-1400°C.

4. The method for comprehensive utilization of all components of leached residues from a high-pressure acid leaching process of laterite nickel ore according to claim 1, characterized in that: The sulfur dioxide flue gas is flue gas in the area of ​​50% to 100% along the traveling direction of the sintering machine trolley, and its average sulfur dioxide concentration is higher than 1 vol%.

5. The method for comprehensive utilization of all components of leached residues from a high-pressure acid leaching process of laterite nickel ore according to claim 1, characterized in that: The granulated slag has a particle size range of 1-10 mm and a glass content higher than 85 wt %.

6. The method for comprehensive utilization of all components of leached residues from high pressure acid leaching of laterite nickel ore according to claim 1, characterized in that: The specific surface area of ​​the granulated slag powder is 400-700 kg / m 2 The particle size D50 of the particles is 8~15μm, and D90 is less than 45μm, and the water content is less than 1 wt%.

7. The method for comprehensive utilization of all components of leached residues from high pressure acid leaching of laterite nickel ore according to claim 1, characterized in that: The alkaline activator includes at least one of NaOH, KOH, Na2CO3, and Na2SiO3.

8. The method for comprehensive utilization of all components of leached residues from high pressure acid leaching of laterite nickel ore according to claim 1, 5, 6 or 7, characterized in that: The backfill material comprises the following components in percentage by weight: 25-50% granulated slag powder; 3-10% alkali activator; 20-40% granulated slag; and 10-25% tailings from high pressure acid leaching process of laterite nickel ore.

9. The method for comprehensive utilization of all components of leached residues from high pressure acid leaching of laterite nickel ore according to claim 8, characterized in that: The backfill material contains no more than 15 wt % of admixture.

10. The method for comprehensive utilization of all components of leached residues from high pressure acid leaching of laterite nickel ore according to claim 9, characterized in that: The admixture includes at least one of fly ash, metakaolin and lime.

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