AU2024267091A1 - Method and system for resource utilization of lateritic nickel ore leaching tailings - Google Patents

Abstract

The present disclosure discloses a method and system for resource utilization of lateritic nickel ore leaching tailings. The method includes: mixing the lateritic nickel ore leaching tailings with a flux to obtain a mixed material; performing a melting and slagging 5 desulfurization on the mixed material to obtain slag and flue gas containing SO 2 ; and mixing the slag with a reducing agent for reduction and iron extraction to obtain molten iron, iron extraction slag and coal gas.

Description

METHOD AND SYSTEM FOR RESOURCE UTILIZATION OF LATERITIC NICKEL ORE LEACHING TAILINGS PRIORITY INFORMATION

[0001] The present disclosure claims the priority to Chinese patent application No.

202311301553.6, titled "Method and System for Resource Utilization of Lateritic Nickel Ore

Leaching Tailings", filed on October 09, 2023 to China National Intellectual Property

Administration, the disclosures of which are hereby incorporated by reference.

TECHNICAL FIELD

[0002] The present disclosure belongs to the technical field of solid waste utilization, and particularly relates to a method and system for resource utilization of lateritic nickel ore

leaching tailings.

BACKGROUND

[0003] Nickel has the characteristics of high mechanical strength, good ductility, infusibility, high temperature resistance, high chemical stability, etc. It is widely used in the field of stainless

steel, new energy, etc., and has become an indispensable metal in current society. In recent years,

with the progress of the technology, the recovery of nickel and cobalt from lateritic nickel ore

with high iron and low magnesium by high pressure sulfuric acid leaching technology has

attracted much attention, and the production capacity has increased year by year.

[0004] The biggest bottleneck of wet leaching of the lateritic nickel ore is the large amount

of tailings. The iron in the tailings mainly exists in the form of hematite. Due to its high water

content, low grade and high sulfur content, the tailings cannot be directly sold to iron and steel

plants as raw materials for iron making. At present, there is no industrial example of

comprehensive recycling and utilization. The tailings are basically treated by stacking, which has extremely high environmental safety hazards.

SUMMARY

[0005] The present disclosure aims to solve one of technical problems in the related art at least to a certain extent. To this end, a purpose of the present disclosure is to provide a method

and system for resource utilization of lateritic nickel ore leaching tailings. The method can not

only solve the problem of environmental protection hazards of the lateritic nickel ore leaching

tailings, but also can comprehensively utilize the valuable elements such as iron and sulfur

therein, resulting in considerable economic benefits.

[0006] In the first aspect of the present disclosure, the present disclosure provides a method for resource utilization of lateritic nickel ore leaching tailings. According to embodiments of

the present disclosure, the method includes:

(1) mixing the lateritic nickel ore leaching tailings with a flux to obtain a mixed material;

(2) performing a melting and slagging desulfurization on the mixed material to obtain slag

and flue gas containing SO 2 ; and

(3) mixing the slag with a reducing agent for reduction and iron extraction to obtain molten

iron, iron extraction slag and coal gas.

[0007] In the method for resource utilization of lateritic nickel ore leaching tailings according to the above embodiment of the present disclosure, the lateritic nickel ore leaching

tailings are used as raw material to solve the problem of the environmental protection hazards

of the lateritic nickel ore leaching tailings. The lateritic nickel ore leaching tailings are mixed

with the flux to obtain the mixed material. The mixed material is subjected to a melting and

slagging desulfurization to obtain slag and flue gas containing SO2, wherein the flue gas

containing SO2 can be used for making acid to realize the comprehensive utilization of sulfur

element in the lateritic nickel ore leaching tailings; the slag can be subjected to reduction to

extract iron to obtain the molten iron, iron extraction slag and coal gas; the obtained molten

iron can be used for steelmaking; the comprehensive utilization of iron element in the lateritic

nickel ore leaching tailings can be achieved; the obtained iron extraction slag can be used for

preparing building raw material; and the obtained coal gas can be used as fuel, thereby producing objective economic benefits. Moreover, the lateritic nickel ore leaching tailings are mixed with the flux before the melting and slagging desulfurization, which can directly adjust the internal structure and the chemical compositions of the slag, improve the metallurgical properties of the slag, reduce the temperature of reduction and iron extraction, and facilitate subsequent reduction and iron extraction. In addition, the melting and slagging desulfurization and the reduction and iron extraction are performed separately. On the one hand, because more heat is required for melting and slagging desulfurization, and less heat is required for reduction and iron extraction, energy consumption can be reduced and production and operating cost can be decreased. On the other hand, a weak reducing atmosphere is used for desulfurization and melting, which is conducive to achieve the decomposition of gypsum and solve the problems that it is difficult to adapt to the composition fluctuation of the lateritic nickel ore leaching tailings due to the narrow mixing range of the reducing agent (too much or too little reducing agent is not conducive to desulfurization) and the problem of bond caused by too high temperature of reduction and desulfurization during conventional reduction and desulfurization.

Thus, the method can solve the problem of the environmental protection hazards in the lateritic

nickel ore leaching tailings, comprehensively utilize the valuable elements therein such as iron

and sulfur, and produce considerable economic benefits, and is low in energy consumption, low

in production cost, simple in process, easy to operate, which is suitable for large-scale

production and has high in practical value.

[0008] In addition, the method for resource utilization of lateritic nickel ore leaching

tailings according to the above embodiment of the present disclosure may also have the

following additional technical features.

[0009] In some embodiments of the present disclosure, the lateritic nickel ore leaching

tailings are pre-dried before the lateritic nickel ore leaching tailings and the flux are mixed,

which is conducive to subsequent distribution and transportation.

[0010] In some embodiments of the present disclosure, in step (1), drying and crushing are

performed after the lateritic nickel ore leaching tailings and the flux are mixed, which is

conducive to increase the efficiency of subsequent melting and slagging desulfurization and

reduce the energy consumption of chemical material.

[0011] In some embodiments of the present disclosure, in step (1), the flux comprises CaO

'I and MgO, which is conducive to the progress of reduction and iron extraction.

[0012] In some embodiments of the present disclosure, in step (1), the lateritic nickel ore leaching tailings and the flux aremixed at a ratio enabling a mass ratio of CaO to SiO 2 in the iron extraction slag to be (0.9-1.2): 1, and a content of MgO in the iron extraction slag to be 6 wt% to 1Owt%, which is conducive to the progress of reduction and iron extraction.

[0013] In some embodiments of the present disclosure, in step (2), a temperature of the melting and slagging desulfurization ranges from 1500°C to 1550°C.

[0014] In some embodiments of the present disclosure, the ends of a first fuel spray lance and a mixed material spray lance extend below the slag during the melting and slagging desulfurization, which is conducive to the progress of melting and slagging desulfurization.

[0015] In some embodiments of the present disclosure, combustion-supporting air adopted by the first fuel spray lance includes oxygen-enriched air, a concentration of oxygen in the oxygen-enriched air being not less than 65 vol%, and an excess air coefficient ranging from 0.95 to 0.98.

[0016] In some embodiments of the present disclosure, in step (3), a temperature of the reduction and iron extraction ranges from 1400°C to 1500°C.

[0017] In some embodiments of the present disclosure, an end of a second fuel spray lance extends below a slag layer in the process of reduction and iron extraction, which is conducive to the progress of reduction and iron extraction.

[0018] In some embodiments of the present disclosure, the reduction and iron extraction is supplemented with heat by a third fuel spray lance and/or an electrode.

[0019] In some embodiments of the present disclosure, when the reduction and iron extraction is supplemented with heat by a third fuel spray lance, the end of the third fuel spray lance extends below the slag layer, and the volume of CO in a reaction system accounts for not less than 80% of the total volume of CO and C02, which can improve the reduction effect and reduce the iron content of the iron extraction slag.

[0020] In some embodiments of the present disclosure, the mixed material is pre-heated in advance before the mixed material is subjected to the melting and slagging desulfurization, which can improve the efficiency of subsequent melting and slagging desulfurization and reduce the energy consumption of the chemical material.

A

[0021] In some embodiments of the present disclosure, a temperature of the preheated mixed material ranges from 500°C to 650°C, which can improve the efficiency of subsequent melting and slagging desulfurization, reduce the energy consumption of the chemical material and avoid the decomposition of sulfate in advance.

[0022] In the second aspect of the present disclosure, the present disclosure provides a system for resource utilization of lateritic nickel ore leaching tailings. According to embodiments of the present disclosure, the system includes: a mixing device having an inlet for the lateritic nickel ore leaching tailings, a flux inlet, and, a mixed material outlet, the mixing device being adapted to mix the lateritic nickel ore leaching tailings with a flux to obtain a mixed material; a melting and slagging desulfurization device having a mixed material inlet, a slag outlet and a flue gas outlet, the mixed material inlet being connected with the mixed material outlet, and the melting and slagging desulfurization device being adapted to perform a melting and slagging desulfurization on the mixed material to obtain slag and flue gas containing SO 2 ; and a reducing device having a slag inlet, a reducing agent inlet, a molten iron outlet, an iron extraction slag outlet, and a coal gas outlet, the slag inlet being connected with the slag outlet, and the reducing device being adapted to mix the slag with a reducing agent for reduction and iron extraction to obtain molten iron, iron extraction slag, and coal gas.

[0023] In the system for resource utilization of lateritic nickel ore leaching tailings according to the above embodiment of the present disclosure, the lateritic nickel ore leaching tailings are used as raw material to solve the problem of the environmental protection hazards of the lateritic nickel ore leaching tailings. The lateritic nickel ore leaching tailings are mixed with the flux by a mixing device to obtain the mixed material. The mixed material is subjected to a melting and slagging desulfurization by a melting and slagging desulfurization device to obtain slag and flue gas containing SO 2, wherein the flue gas containing SO2 can be used for making acid to realize the comprehensive utilization of sulfur element in the lateritic nickel ore leaching tailings; the slag can be reduced by the reducing device to extract iron to obtain molten iron, iron extraction slag and coal gas; the obtained molten iron can be used for steelmaking; the comprehensive utilization of iron element in the lateritic nickel ore leaching tailings can be achieved; the obtained iron extraction slag can be used for preparing building raw material; and the obtained coal gas can be used as fuel, thereby producing objective economic benefits. Moreover, the mixing device is provided with the inlet for the lateritic nickel ore leaching tailings, the flux inlet and the mixed material outlet; the melting and slagging desulfurization device is provided with a mixed material inlet connected with the mixed material outlet; and the lateritic nickel ore leaching tailings are mixed with the flux before the melting and slagging desulfurization, which can directly adjust the internal structure and the chemical compositions of the slag, improve the metallurgical properties of the slag, reduce the temperature of reduction and iron extraction, and facilitate subsequent reduction and iron extraction. In addition, melting and slagging desulfurization and reduction and iron extraction are performed in different apparatuses respectively. On the one hand, because more heat is required for melting and slagging desulfurization, and less heat is required for reduction and iron extraction, energy consumption can be reduced and production and operating cost can be decreased. On the other hand, a weak reducing atmosphere is used for desulfurization and melting, which is conducive to achieve the decomposition of gypsum and solve the problems that it is difficult to adapt to the composition fluctuation of the lateritic nickel ore leaching tailings due to the narrow mixing range of the reducing agent (too much or too little reducing agent is not conducive to desulfurization) and the problem of bond caused by too high temperature of reduction and desulfurization during conventional reduction and desulfurization. Thus, the system can solve the problem of the environmental protection hazards in the lateritic nickel ore leaching tailings, comprehensively utilize the valuable elements therein such as iron and sulfur, and produce considerable economic benefits, and is low in energy consumption, low in production cost, simple in process, easy to operation, which is suitable for large-scale production and has high in practical value.

[0024] In addition, the system for resource utilization of lateritic nickel ore leaching tailings according to the above embodiment of the present disclosure may also have the following additional technical features.

[0025] In some embodiments of the present disclosure, the system further includes a pre drying treatment device; wherein: the pre-drying treatment device has a lateritic nickel ore leaching tailings inlet and a dried leaching tailings outlet connected with the lateritic nickel ore leaching tailings inlet; and the pre-drying treatment device is adapted to pre-dry the lateritic

A1 nickel ore leaching tailings before the lateritic nickel ore leaching tailings are mixed with the flux, which is conducive to subsequent distribution and transportation.

[0026] In some embodiments of the present disclosure, the system further includes a drying and crushing device; wherein: the drying and crushing device has an inlet for a material to be

treated and an outlet for a dried and crushed material, the inlet for the material to be treated

being connected with the mixed material outlet; and the outlet for the dried and crushed material

being connected with the mixed material inlet; and the drying and crushing device is adapted

to dry and crush the mixed material before the mixed material is supplied to the melting and

slagging desulfurization device; and supply the dried and crushed mixed material obtained to

the melting and slagging desulfurization device, which improves the efficiency of subsequent

melting and slagging desulfurization and reduces the energy consumption of the chemical

material.

[0027] In some embodiments of the present disclosure, the system further includes: a preheating device, wherein, the preheating device has a mixed material inlet, a preheated

material outlet and a preheated tail gas outlet; the mixed material inlet being connected with the

mixed material outlet; the preheated material outlet being connected with the mixed material

inlet; and the preheating device being suitable for preheating the mixed material before the

mixed material is supplied to the melting and slagging desulfurization device; and supply the

preheated mixed material to the melting and slagging desulfurization device; and a dust

collecting device, the dust collecting device has a preheated tail gas inlet, a dust collecting outlet

and an outlet for tail gas after dust collection; the preheated tail gas inlet being connected with

the preheated tail gas outlet; the dust collecting outlet being connected with the mixed material

inlet; and the outlet for the tail gas after dust collection being connected with the pre-drying

treatment device, which is conducive to increase the efficiency of subsequent melting and

slagging desulfurization and reduce the energy consumption of the chemical material.

[0028] In some embodiments of the present disclosure, the melting and slagging

desulfurization device includes: a melting and slagging desulfurization device body including

a furnace and a slag region from top to bottom; a mixed material spray lance having an end

extending into the slag region; a first fuel spray lance having ant end extending into the slag

region; a secondary tuyere arranged on the furnace; a flue duct in communication with the

'7 furnace; and a slag outlet arranged on a side wall of the slag region. Thus, the comprehensive utilization of sulfur element in the lateritic nickel ore leaching tailings is realized.

[0029] In some embodiments of the present disclosure, the melting and slagging desulfurization device further includes a flue gas waste heat recovery device connected with

the flue. Thus, the heat utilization rate of the whole process can be increased and the energy

consumption can be reduced.

[0030] In some embodiments of the present disclosure, the reducing device includes: a reducing device body, having, along a horizontal direction, a reducing region, a carburizing

region and a settling region arranged, a partition wall being arranged between the carburizing

region and the settling region, and a bottom end of the partition wall being spaced apart from a

bottom of the reducing device body by a distance; a slag inlet arranged in the reducing region;

a reducing agent arranged in the reducing region; a second fuel spray lance arranged in the

reducing region and having an end extending below the slag layer of the reducing region; a

carburizing agent spray lance arranged in the carburizing region and having an end extending

into the slag layer of the carburizing region; and a heat supplementing device arranged in the

carburizing region and the settling region. Thus, the comprehensive utilization of iron element

in the lateritic nickel ore leaching tailings is realized.

[0031] In some embodiments of the present disclosure, the system further includes a coal

gas utilization device; wherein the coal gas utilization device is connected with the coal gas

outlet, the pre-drying treatment device, the preheating device and the melting and slagging

desulfurization device; and the coal gas utilization device is adapted to collect and supply the

the coal gas generated in the reducing device, as fuel, to at least one of the pre-drying treatment

device, the preheating device and the melting and slagging desulfurization device. Thus, it can

improve the utilization efficiency of coal gas and the heat utilization rate of the entire

technology, thereby reducing energy consumption.

[0032] In some embodiments of the present disclosure, a top of the slag region is spaced

apart from a bottom of the melting and slagging desulfurization device body by a distance not

less than 800 mm; an end of the mixed material spray lance is spaced apart from the top of the

slag region by a distance not less than 200 mm, and an end of the first fuel spray lance is spaced

apart from the top of the slag region by a distance not less than 200 mm, which is conducive to

Q improve the melting efficiency.

[0033] In some embodiments of the present disclosure, an end of the second fuel spray lance is spaced apart from the top of the slag layer by a distance not less than 200 mm and is located

above a molten iron layer.

[0034] The additional aspects and advantages of the present disclosure will be set forth in

part in the following description, and in part will become apparent from the following

description, or will be learned by the practice of the present disclosure.

BRIEF DESCRIPTION OF DRAWINGS

[0035] The above and/or additional aspects and advantages of the present disclosure will become apparent and more readily appreciated from the description of the embodiments in

combination with the following figures, wherein:

[0036] Fig. 1 is a flowchart of a method for resource utilization of lateritic nickel ore

leaching tailings according to an embodiment of the present disclosure;

[0037] Fig. 2 is a structural schematic diagram of a system for resource utilization of

lateritic nickel ore leaching tailings according to an embodiment of the present disclosure;

[0038] Fig. 3 is a first structural schematic diagram of a melting and slagging desulfurization device according to an embodiment of the present disclosure;

[0039] Fig. 4 is a second structural schematic diagram of a melting and slagging

desulfurization device according to an embodiment of the present disclosure;

[0040] Fig. 5 is a structural schematic diagram of a melting and slagging desulfurization

device according to another embodiment of the present disclosure;

[0041] Fig. 6 is a structural schematic diagram of a system for resource utilization of

lateritic nickel ore leaching tailings according to another embodiment of the present disclosure;

[0042] Fig. 7 is a first structural schematic diagram of a reducing device according to an

embodiment of the present disclosure;

[0043] Fig. 8 is a second structural schematic diagram of a reducing device according to an

embodiment of the present disclosure;

[0044] Fig. 9 is a structural schematic diagram of a system for resource utilization of lateritic nickel ore leaching tailings according to another embodiment of the present disclosure;

[0045] Fig. 10 is a structural schematic diagram of a system for resource utilization of lateritic nickel ore leaching tailings according to another embodiment of the present disclosure;

[0046] Fig. 11 is a structural schematic diagram of a system for resource utilization of lateritic nickel ore leaching tailings according to another embodiment of the present disclosure;

[0047] Fig. 12 is a structural schematic diagram of a system for resource utilization of lateritic nickel ore leaching tailings according to another embodiment of the present disclosure; and

[0048] Fig. 13 is a structural schematic diagram of a system for resource utilization of lateritic nickel ore leaching tailings according to another embodiment of the present disclosure.

DESCRIPTION OF EMBODIMENTS

[0049] Embodiments of the present disclosure will be described below in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary embodiments, and are intended to explain the present disclosure, and should not be understood as a limitation to the present disclosure.

[0050] In the description of the present disclosure, it should be understood that terms such as "central", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the

direction or position relationships based on the direction or position relationships shown in the drawings, and are only intended to facilitate the description of the present disclosure and the simplification of the description rather than to indicate or imply that the indicated device or element must have a specific direction or constructed and operated in a specific direction, and thus cannot be understood as a limitation to the present disclosure.

[0051] In addition, the terms such as "first" and "second" are only used for the purpose of description, rather than being understood to indicate or imply relative importance or implicitly

In indicate the number of indicated technical features. Thus, the features limited with "first" and "second" can explicitly or impliedly include at least one of the features. In the description of the present disclosure, the meaning of "a plurality of' means at least two, for example two, three, etc., unless otherwise clearly specified.

[0052] In the present disclosure, unless otherwise specifically specified and defined, the terms such as "mounted", "connected", "connecting", "fixed" and the like should be understood in broad sense, and for example, may be fixedly connected, or may be detachably connected, or integrated, may be mechanically connected, or may be electrically connected, and may be directly connected or indirectly connected by means of an intermediate medium may be inner communication of two elements or interaction relationship of two elements unless otherwise clearly specified. For those ordinary skilled in the art, the specific meanings of the above terms in the present disclosure may be understood according to specific conditions.

[0053] In the present disclosure, unless otherwise clearly specified and limited, a first feature "above" or "below" a second feature may mean that the first feature and the second feature are in direct contact, or the first feature and the second feature are in indirect contact through an intermediary. Moreover, the first feature "on", "above" and "over" the second feature may mean that the first feature is directly above or obliquely above the second feature, or merely indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature is "under", "below" and "beneath" the second feature may mean that the first feature is directly below or obliquely below the second feature, or may just indicate that the horizontal height of the first feature is lower than that of the second feature.

[0054] In a first aspect of the present disclosure, the present disclosure provides a method for resource utilization of lateritic nickel ore leaching tailings. According to embodiments of the present disclosure, referring to Fig. 1, the method includes the following.

[0055] S100: mixing the lateritic nickel ore leaching tailings with a flux.

[0056] In this step, the lateritic nickel ore leaching tailings are mixed with the flux to obtain the mixed material. Specifically, the lateritic nickel ore leaching tailings may be the tailings after filter pressing in a lateritic nickel ore wet leaching system (water content is 30 wt% to 45 wt%). Based on the dry basis of the lateritic nickel ore leaching tailings, the content of calcium element in the lateritic nickel ore leaching tailings is not greater than 8 wt%, and the content of iron element is 25 wt% to 50 wt% and the content of sulfur element is 3 wt% to 10 wt%. The flux includes CaO and MgO, which can be pure CaO and MgO, or various materials rich in

CaO and MgO, such as limestone, dolomite, steel slag, high magnesium lateritic ore, etc. By

mixing the lateritic nickel ore leaching tailings with the flux, the internal structure and the

chemical compositions of the obtained slag can be adjusted to improve the metallurgical

properties of the slag, and reduce the temperature of reduction and iron extraction, which is

conducive to the process of reduction and iron extraction. Moreover, the lateritic nickel ore

leaching tailings and the flux are mixed at a ratio enabling a mass ratio of CaO to SiO 2 in the

iron extraction slag obtained by reduction and iron extraction to be (0.9-1.2): 1 of, and a content

of of MgO in the iron extraction slag to be 6 wt% tol0 wt%.

[0057] According to the embodiment of the present disclosure, the lateritic nickel ore leaching tailings are pre-dried before the lateritic nickel ore leaching tailings are mixed with

the flux, and the water content of the pre-dried lateritic nickel ore leaching tailings ranges from

15 wt% to 20 wt%, which is neither dusty nor clumped, and is conducive to the subsequent

distribution and transportation. Moreover, the pre-drying can be performed by using a drying

kiln and a dust collecting device. The drying kiln can adopt a steam dryer for indirect heat

exchange (steam temperature >120°C) or a rotary drying kiln for direct heat exchange. For

example, when the steam dryer is adopted, the heat source can be the steam generated in the

process of waste heat recovery of flue gas in the subsequent step of melting and slagging

desulfurization and the step of reduction and iron extraction, and the steam temperature is

>120°C; when the rotary drying kiln is adopted, a cocurrent drying kiln is preferred; the hot air

temperature is < 700°C; the tail gas temperature ranges from 105°C to 120°C; and the heat

source of the rotary kiln can adopt pulverized coal, coal gas or high temperature tail gas.

[0058] S200: performing a melting and slagging desulfurization on the mixed material.

[0059] In this step, the mixed material is subjected to a melting and slagging desulfurization

to obtain slag and flue gas containing SO 2 . Specifically, the ends of a first fuel spray lance and

a mixed material spray lance extend below the slag, and the oxygen-enriched air and the fuel

enter below the slag by the first fuel spray lance for submerged combustion, to provide heat for

the melting of the mixed material. The specific chemical reaction equations include

CaHbOcNSe+02--CO+H20+N2+SO2, and CO+02-CO2t. The mixed material enters below

1) the slag by the mixed material spray lance, and undergo the reactions of decomposition

(CaCO3--CaO+CO27), desulfurization (A12(SO 4) 3+CO--Al 2 0 3+CO2T+SO27,

Fe2(SO 4 )3+CO--Fe2O3+CO2t+SO2t and CaSO4+CO--CaO+CO2T+SO2t), melting and

slagging (FeO+SiO2--2FeO-SiO2 and Fe203+CaO--CaO-Fe2O3) under the action of

combustion heat at 1500°C to 1550°C, to obtain high temperature slag at about 1500°C and flue

gas containing S02. Therefore, the weak reducing atmosphere is used for desulfurization and

melting, which is conducive to achieve the decomposition of gypsum and solve the problems

that it is difficult to adapt to the composition fluctuation of the lateritic nickel ore leaching

tailings due to the narrow mixing range of the reducing agent (too much or too little reducing

agent is not conducive to desulfurization) and the problem of bond caused by too high

temperature of reduction and desulfurization during conventional reduction and desulfurization.

Specifically, the first fuel spray lance can adopt coal, gas, pulverized coal, fuel oil, natural gas

and other fuels. The combustion-supporting air used may include oxygen-enriched air having a

concentration of oxygen not less than 65 vol% and an excess air coefficient ranging from 0.95

to 0.98. The slag type can be Fe-Fe30 4-Ca-SiO2-MgO-Al203, which has very good fluidity

at the melting temperature of the mixed material.

[0060] According to the embodiments of the present disclosure, in order to improve the

subsequent reduction efficiency, an appropriate amount of reducing agent can also be added to

the above mixed material for preliminary reduction, and the specific chemical reaction

equations include: Fe203+CO--Fe3O 4 +CO2T and Fe30 4 +CO--FeO+CO27.

[0061] According to the embodiments of the present disclosure, secondary air can be blown

into the flue gas containing SO2 for secondary combustion, and the CO in the flue gas

containing S02 is burned off. Specifically, the 02 content in the flue gas containing S02 after

secondary combustion can be controlled to be between 2 vol% and 4 vol%. The inventors have

found that if the content of 02 is too low, secondary combustion is incomplete; if the content of

02 is too high, the amount of the flue gas will be increased, and the proportion of S02 converted

into S03 will be increased. By controlling the content of 02 in the flue gas containing S02 after

secondary combustion within the above rang, the present disclosure can not only make the

secondary combustion reaction complete, but also can reduce the flue gas and the proportion of

S02 converted into S03.

1'2

[0062] According to the embodiments of the present disclosure, the flue gas containing SO 2

above can be firstly cooled to below 1200°C by recovering waste heat by a flue gas waste heat

boiler to generate steam, then cooled to about 200°C by a flue gas heat exchanger to generate

hot air of 700°C to 800°C, and finally sent for acid production after dust collection treatment,

thereby realizing the comprehensive utilization of sulfur element in the lateritic nickel ore

leaching tailings. The steam generated by recovering the waste heat from the flue gas waste

heat boiler can be used to pre-dry the tailings after filter pressing in the lateritic nickel ore wet

leaching system. The hot air of 700°C-800°C obtained after heat exchange by the flue gas heat

exchanger can be used as a heat source for preheating the mixed material, and the insufficient

part can be supplemented by burning the coal gas, pulverized coal, fuel oil or other fuels. Thus,

the heat utilization rate of the whole process can be increased and the energy consumption can

be reduced.

[0063] According to the embodiments of the present disclosure, prior to melting and slagging desulfurization, the mixed material obtained by mixing the lateritic nickel ore leaching

tailings with the flux can be dried and crushed. Therefore, the particle size of the mixed material

can be decreased, the specific surface area of the mixed material is increased, free water in the

mixed material is removed, and partial gypsum in the lateritic nickel ore leaching tailings is

dehydrated into semi-hydrated gypsum and CaSO 4 (H 2 0 - H20 t CaSO4-2H20--CaSO4-0.5H20+H207 120°C-150°C, and

CaSO4 -0.5H20-CaSO 4+H20t>165°C), thereby increasing the efficiency of subsequent

melting and slagging desulfurization and reducing energy consumption of the chemical material.

Meanwhile, the mixed material can be homogenized, which is beneficial to the reduction and

iron extraction. Specifically, the water content of the lateritic nickel ore leaching tailings after

drying and crushing can be not greater than 2 wt%, the particle size can be not greater than 2

mm, the flux particle size can be not greater than 2 mm, and the heat source of drying and

crushing can be coal gas, pulverized coal, fuel oil or other fuels. Moreover, a crusher, a

pneumatic powder lifting device and a dust collecting device can be used for drying and

crushing. A ball mill, a vertical mill, an air swept mill and a hammer crusher with both crushing

and drying functions can be used as the crusher; the pneumatic powder lifting device can be a

pneumatic lifting pump; and the dust collecting device can be a bag dust collector. The hot air

1A temperature at an inlet of the crusher can be 600°C to 800°C. The tail gas temperature of the bag can be 120°C to 150°C; the air-charge ratio is 3 200 Nm3/t (the specific amount required is obtained by the thermal equilibrium calculation according to the water content of the wet material and the hot air temperature); and the airflow velocity of the pneumatic air lifting device is 4 m/s to 10 m/s (if the air flow velocity is too low, the particle size of the dried slag is too fine, and the dust rate is too high when melting; if the air flow velocity is too high, on the one hand, the particle size of the dry slag is too coarse and the pipeline wear is large, and on the other hand, the system resistance is large and the energy consumption is high). The retention time of the material in the pneumatic powder lifting device is >2s, and the coal gas can be used as the heat source of the crusher. When the coal gas is insufficient, other fuels such as pulverized coal and fuel oil can also be used.

[0064] According to the embodiments of the present disclosure, prior to performing the melting and slagging desulfurization of the mixed material, the above mixed material can also

be preheated in advance, so that they can be rapidly preheated and decomposed, and the

temperature can be appropriately raised. Specific chemical reaction equations include:

H 20--H 207, CaSO4 -2H20--CaSO 4+H207, CaSO4 -0.5H20--CaSO 4+H207,

Fe(OH)3--Fe2O3+H20t, Al(OH) 3 -- Al 2 0 3+H 207, Ca(OH)2--CaO+H207, and

CaMgC20 6-CaCO3+MgO+H20t. Thus, it can improve the efficiency of subsequent melting

and slagging desulfurization and reduce the energy consumption of the chemical material.

[0065] Specifically, 3-5 stage cyclone preheater and an electric dust collector can be used

for the preheating. The preheating mode can be countercurrent heat exchange. The hot air of

700°C to 800°C generated in the waste heat recovery process in the subsequent step of the

melting and slagging desulfurization can be used as the preheating heat source, and the

insufficient part can be supplemented by burning coal gas, pulverized coal, fuel oil and other

fuels. The temperature of the hot air at the inlet of the cyclone preheater ranges from 700°C to

800°C; the temperature of the mixed material after preheating can be 500°C to 650°C; and the

temperature of the tail gas after preheating is < 200°C. The tail gas is evacuated after dust

removal by the electric dust collector, and the collected dust is returned to the cyclone preheater.

The tail gas after dust removal can be used as a heat source for pre-drying to reduce the energy

consumption of pre-drying. Moreover, the inventors have found that if the temperature of the

1< hot air used for preheating is too high, part of the sulfate (decomposition temperature of aluminum sulfate is 685°C) will decompose in advance, which is not conducive to the subsequent recovery and utilization of S02; and if the temperature of the hot air used for preheating is too low, the temperature of the mixed material will be too low, which is not conducive to improving the efficiency of subsequent melting and slagging desulfurization and reducing the energy consumption of the chemical material. By controlling the temperature of the hot air used for preheating within the above range, the present disclosure can not only improve the efficiency of subsequent melting and slagging desulfurization and reduce the energy consumption of the chemical material, but also can avoid the decomposition of sulfate in advance, which is conducive to the subsequent recovery and utilization of SO2. In addition, high temperature tail gas can be produced after preheating the mixed materials with hot air

, and the tail gas can be used to pre-dry the tailings afterfilter pressing in the lateritic nickel ore

wet leaching system, which can realize the full utilization of waste heat, thereby reducing the

energy consumption.

[0066] S300: mixing the slag with a reducing agent for reduction and iron extraction.

[0067] In this step, the slag is mixed with the reducing agent for reduction and iron

extraction to obtain molten iron, iron extraction slag and coal gas. Specifically, the end of the

reducing agent spray lance and the end of the second fuel spray lance extend below a slag layer,

and the oxygen-enriched air and the fuel enter below the slag layer by the second fuel spray

lance for submerged combustion to provide heat for reduction and iron extraction. The specific

chemical reaction equations include CaHbOcNdSe+02--CO+H20+N2+SO2, and CO+02--CO27.

The reducing agent enter below the slag layer by the reducing agent spray lance, and is mixed

with the slag and reduced for iron extraction at 1400°C-1500°C. Under the action of the

reducing agent, the iron oxide in the slag is reduced to metallic iron to obtain molten iron, iron

extraction slag and coal gas. The specific chemical reaction equations include:

Fe30 4+CO-*FeO+CO2T, FeO+C--Fe+COT and CaO+SiO2-2CaO-SiO2. The molten iron

will settle at the bottom of the furnace due to high density, so it will be separated from the iron

extraction slag. The discharge temperature of the molten iron can be 1400°C to 1500°C, and

the discharge temperature of the iron extraction slag can be 1450°C to 1550°C. The iron content

of the iron extraction slag is < 5%, and the molten iron can be used for steelmaking, so as to

I1 realize the comprehensive utilization of iron element in the lateritic nickel ore leaching tailings.

The iron extraction slag can be used as building materials after being subjected to water

fragmentation. In addition, because more heat is required for melting and slagging

desulfurization, and less heat is required for reduction and iron extraction, it can reduce the

energy consumption and decrease production and operation cost by separating melting and

slagging desulfurization from reduction and iron extraction.

[0068] Specifically, a reduction and iron extraction furnace can be used for the reduction and iron extraction. The anthracite or coke fines can be used as reducing agent, the particle size

of which can be 2 mm to 5 mm, and the fixed carbon content is >70%. The amount of the

reducing agent for producing each ton of molten iron is not less than 300 kg. Meanwhile, in the

process of reduction and iron extraction, the carburizing agent can be sprayed into the molten

iron layer, thereby improving the carburizing efficiency. The anthracite or coke fines can be

used as the carburizing agent, and a CaO-SiO2-MgO-Al203 slag system can be used for

reduction and iron extraction. By adding the flux in the preheating process, the mass ratio of

CaO to SiO 2 in the iron extraction slag can be controlled to be (0.9-1.2): 1; the content of MgO

in the iron extraction slag can be controlled to range from 6 wt% to 10 wt%; the viscosity of

the iron extraction slag at 1450°C is less than 0.8Pa-s, having very good fluidity.

[0069] According to the embodiments of the present disclosure, the end of the second fuel

spray lance may be located below 200 m on the upper surface of the slag layer and above the

surface of the molten iron. For the second fuel spray lance, high calorific value fuels such as

pulverized coal, natural gas, and fuel oil can be used. The combustion-supporting air used may

include oxygen-enriched air having a concentration of oxygen not less than 65 vol%. In addition,

the inventors have found that by controlling the excess air coefficient, the volume of CO in the

reaction system accounts for not less than 80% of the total volume of CO and C02, which is

conducive to improving the reduction effect and reducing the iron content of the iron extraction

slag.

[0070] According to the embodiments of the present disclosure, heat can be supplemented

by a third fuel spray lance and/or an electrode in the process of reduction and iron extraction.

When the heat is supplemented by the third fuel spray lance, the end of the third fuel spray

lance extends below the slag layer, and the oxygen-enriched air and the fuel enter below the

1'7 slag layer by the third fuel spray lance for submerged combustion to supplement the heat for reduction and iron extraction. When the heat is supplemented by the electrode, the end of the electrode extends below the slag layer to supplement the heat for reduction and iron extraction.

Specifically, for the third fuel spray lance, high calorific value fuels such as pulverized coal,

natural gas, and fuel oil can be used. The combustion-supporting air used may include oxygen

enriched air having a concentration of oxygen not less than 65 vol%. In addition, the inventors

have found that by controlling the excess air coefficient, the volume of CO in the reaction

system accounts for not less than 80% of the total volume of CO and C02, which can improve

the reduction effect and reduce the iron content of the iron extraction slag.

[0071] According to the embodiments of the present disclosure, the coal gas obtained from

the reduction and iron extraction is collected under negative pressure, and the clean coal gas

can be obtained after waste heat recovery, cooling and dust removal. Most of the clean coal gas

is used as fuel for melting and slagging desulfurization, and the rest is used as a heat source for

preheating, drying and crushing. The steam generated from waste heat recovery can be used to

pre-dry the tailings after filter pressing in the lateritic nickel ore wet leaching system, which

can improve the utilization efficiency of the coal gas (compared with conventional gas power

generation) and the heat utilization rate of the entire process, thereby reducing the energy

consumption. Moreover, the coal gas utilization device can be used for the waste heat recovery,

cooling and dust removal of the coal gas. The coal gas utilization device can use a coal gas

waste heat boiler, a cooling dust collecting device, a pressurization fan, a coal gas storage tank

and a torch. After the coal gas comes out of the reduction and iron extraction furnace, the coal

gas is cooled to about 850°C to 1000°C through the flue duct of the coal gas waste heat boiler,

and then quenched to below 200°C by the cooling dust collecting device. The quenched coal

gas is pressurized by the fan, then fed into the coal gas storage tank, and can be used as fuel for

the steps of pre-drying, pre-heating, desulfurizing and melting.

[0072] Thus, the method for resource utilization of lateritic nickel ore leaching tailings in

the present disclosure can solve the problem of the environmental protection hazards in the

lateritic nickel ore leaching tailings, comprehensively utilize the valuable elements therein such

as iron and sulfur, and produce considerable economic benefits, and is low in energy

consumption, low in production cost, easy to operate, suitable for large-scale production and

1Q high in practical value. Moreover, by separately performing the operations of pre-drying, drying and crushing, preheating, melting and slagging desulfurization, and reduction and iron extraction, the advantages of the various stages are fully utilized; the steam produced by waste heat recovery in melting and slagging desulfurization and reduction and iron extraction or the tail gas in the preheating process is pre-dried; and the coal gas produced in the reduction and iron extraction is subjected to drying and crushing, preheating and melting and slagging desulfurization, thereby achieving high-efficiency utilization of the coal gas (compared with the conventional coal gas power generation). It should be noted that, the method can also be used to produce nickel iron from the lateritic nickel ore, thereby replacing a rotary kiln electric furnace (RKEF) technology.

[0073] In the second aspect of the present disclosure, the present disclosure provides a system for resource utilization of lateritic nickel ore leaching tailings. According to the

embodiments of the present disclosure, referring to Fig. 2, the system includes: a mixing device

100, a melting and slagging desulfurization device 200 and a reducing device 300.

[0074] According to the embodiments of the present disclosure, referring to Fig. 2, the mixing device 100 has an inlet 101 for lateritic nickel ore leaching tailings, a flux inlet 102, and

a mixed material outlet 103, and is adapted to mix the lateritic nickel ore leaching tailings with

a flux to obtain a mixed material. Specifically, the water content of the lateritic nickel ore

leaching tailings ranges from 15 wt% to 20 wt%, which is neither dusty nor clumped, and is

conducive to the subsequent distribution and transportation. Based on the dry basis of the

lateritic nickel ore leaching tailings, the content of calcium element in the lateritic nickel ore

leaching tailings is not greater than 8 wt%, and the content of iron element ranges from 25 wt%

to 50 wt% and the content of sulfur element ranges from 3 wt% tolO wt%. The flux comprises

CaO and MgO. When the system works, the lateritic nickel ore leaching tailings are fed into the

mixing device 100 via the inlet 101 for lateritic nickel ore leaching tailings. At the same time,

the flux is fed into the mixing device 100 through the flux inlet 102, the lateritic nickel ore

leaching tailings and the flux are mixed in the mixing device 100 to obtain the mixed material.

The mixed material is discharged through the mixed material outlet 103. By mixing the lateritic

nickel ore leaching tailings with the flux before the melting and slagging desulfurization, the

internal structure and the chemical compositions of the slag obtained later can be adjusted to improve the metallurgical properties of the slag and reduce the temperature of reduction and iron extraction, which is conducive to the process of reduction and iron extraction. The lateritic nickel ore leaching tailings and the flux are mixed at a ratio enabling a mass ratio of CaO to

SiO2 in the iron extraction slag obtained by reduction and iron extraction to be (0.9-1.2): 1, and

the content of MgO in the iron extraction slag to be 6wt% to 10 wt%.

[0075] According to the embodiments of the present disclosure, referring to Figs. 3-4, the melting and slagging desulfurization device 200 has a mixed material inlet 201, a slag outlet

202 and a flue gas outlet 203, the mixed material inlet 201 is connected with the mixed material

outlet 103, and the melting and slagging desulfurization device is adapted to perform a melting

and slagging desulfurization on the mixed material to obtain slag and flue gas containing S02.

Specifically, the melting and slagging desulfurization device 200 can include a melting and

slagging desulfurization device body 204, a mixed material spray lance 205, a first fuel spray

lance 206, a secondary tuyere 207 and a flue duct 208. The melting and slagging desulfurization

device body 204 includes a furnace 2041 and a slag region 2042 from top to bottom. The mixed

material spray lance 205 is provided with the mixed material inlet 201; the end of the mixed

material spray lance 205 and the end of the first fuel spray lance 206 extend into the slag region

2042; the secondary tuyere 207 is arranged on the furnace 2041; the flue duct 208 is

communicated with the furnace 2041; the flue duct 208 is provided with the flue gas outlet 203;

and the slag outlet 202 is arranged on a side wall of the slag region 2042. The oxygen-enriched

air and the fuel enter below the slag by thefirst fuel spray lance 206 for submerged combustion

to provide heat for the melting of the mixed material. The specific chemical reaction equations

include CaHbOcNSe+02-CO+H20+N2+SO2, and CO+02-CO2t. The mixed material enters

below the slag by the mixed material spray lance 205, and undergo the reactions of

decomposition (CaCO3--CaO+CO27), desulfurization (A 2 (SO4) 3 +CO--Al 2 0 3 +CO2T+SO27,

Fe2(SO 4)3+CO--Fe2O3+CO2t+SO2t and CaSO 4+CO--CaO+CO2T+SO2t), melting and

slagging (FeO+SiO2--2FeO-SiO2 and Fe203+CaO--+CaO-Fe2O3) under the action of

combustion heat at 1500°C to 1550°C to obtain high temperature slag at about 1500°C and flue

gas containing SO2. Therefore, the reduction, desulfurization and melting and slagging can be

performed separately. The weak reducing atmosphere is used for desulfurization and melting,

which is conducive to achieve the decomposition of gypsum and solve the problem that it is difficult to adapt to the composition fluctuation of the lateritic nickel ore leaching tailings due to the narrow mixing range of the reducing agent (too much or too little reducing agent is not conducive to desulfurization) and the problem of bond caused by too high temperature of reduction and desulfurization during conventional reduction and desulfurization. The obtained high temperature slag is discharged through the slag outlet 202, and the flue gas containing SO2 enters the furnace 2041. The secondary air is blown into the furnace 2041 via the secondary tuyere 207 to make the flue gas containing S02 undergo secondary combustion and discharge through the flue gas outlet 203 to ensure that the 02 content in the flue gas containing S02 discharged through the flue gas outlet 203 is between 2 vol% and 4 vol%, which can make the CO in the flue gas containing S02 burn off and reduce the proportion of the flue gas and S02 converted into S03.

[0076] According to the embodiments of the present disclosure, a top of the slag region 2042 is spaced apart from a bottom of the melting and slagging desulfurization device body 204 by a distance not less than 800 mm to avoid damaging the furnace bottom when the slag is stirred to improve the reaction efficiency. The end of the mixed material spray lance 205 is spaced apart from the top of the slag region 2042 by a distance not less than 200 mm. The end of the first fuel spray lance 206 is spaced apart from the top of the slag region 2042 by a distance less than 200 mm. The mixed material is pneumatically conveyed to 200 mm below the top of the slag region 2042 in the melting and slagging desulfurization device body 204 by the mixed material spray lance 205. The oxygen-enriched air and the fuel are injected to 200 mm below the top of the slag region 2042 by the first fuel spray lance 206 for submerged combustion to provide heat for melting of the mixed material to improve the melting efficiency. For the first fuel spray lance 206, high calorific value fuels such as pulverized coal, natural gas, and fuel oil can be used. The combustion-supporting air used may include oxygen-enriched air having a concentration of oxygen not less than 65 vol%. The excess air coefficient may be 0.95 to 0.98, and the flux slag type can be FeO-Fe3O 4 -CaO-SiO2-MgO-Al203, which has very good fluidity at the melting temperature of the mixed material.

[0077] According to the embodiments of the present disclosure, in order to improve the reduction efficiency, an appropriate amount of the reducing agent can also be added into the above mixed material. Specific chemical reaction equations include: Fe203+CO--Fe3O 4+CO27,

I1 and Fe30 4+CO--FeO+CO27.

[0078] According to the embodiments of the present disclosure, the melting and slagging desulfurization device body 204 can be a melt pool smelting furnace. The melt pool smelting

furnace can include a furnace bottom 2043, a furnace wall 2044 and a furnace top 2045. The

furnace wall 2044 is arranged around the furnace bottom 2043; the furnace top 2045 covers the

furnace wall 2044; the furnace bottom 2043 can be an adiabatic structure; the furnace wall 2044

can be of a water jacket embedded refractory brick structure; both the slag outlet 202 and the

secondary tuyere 207 are arranged on the furnace wall 2044; and the slag outlet 202 can be a

suction mouth. The end of the mixed material spray lance 205 and the end of the first fuel spray

lance 206 can extend into the melt pool smelting furnace through the furnace wall 2044, and

when the slag is stirred, the mixed material spray lance 205 and the first fuel spray lance 206

can be lifted. Meanwhile, when the melt pool smelting furnace is used for oxygen-enriched melt

pool smelting, the low-priced lignite can be utilized, thereby reducing the cost. It can be

understood that, referring to Fig. 5, the end of the mixed material spray lance 205 can also

extend into the melt pool smelting furnace by the furnace top 2045.

[0079] According to the embodiments of the present disclosure, referring to Fig. 6, the melting and slagging desulfurization device 200 further includes a flue gas waste heat recovery

device 21 and an electric dust collector (not shown) connected to each other, wherein the flue

gas waste heat recovery device 21 is connected with the flue gas outlet 203 on the flue duct 208.

Specifically, the flue gas waste heat recovery device 21 can include a flue gas waste heat boiler

(not shown) and a flue gas heat exchanger (not shown) connected to each other. The flue gas

containing S02 discharged from the flue gas outlet 203 can be firstly cooled to 1200°C or below

by a flue gas waste heat boiler to generate steam, then cooled to about 200°C by a flue gas heat

exchanger to generate hot air of 700 to 800°C, and finally sent for acid production after the dust

is collected by the electric dust collector, thereby realizing comprehensive utilization of the

sulfur element in the lateritic nickel ore leaching tailings. The steam generated by recovering

the waste heat from the flue gas waste heat boiler can be used to pre-dry the tailings after filter

pressing in the lateritic nickel ore wet leaching system. The hot air of 700-800°C obtained after

heat exchange by the flue gas heat exchanger can be used as a heat source for preheating the

mixed material, and the insufficient part can be supplemented by burning the coal gas,

11) pulverized coal, fuel oil or other fuels, thereby increasing the heat utilization rate of the whole process and reducing the energy consumption.

[0080] According to the embodiments of the present disclosure, referring to Figs. 7-8, the reducing device 300 includes a slag inlet 301, a reducing agent inlet 302, a molten iron outlet

303, an iron extraction slag outlet 304 and a coal gas outlet 305, wherein the slag inlet 301 is

connected with the slag outlet 202. The reducing device is adapted to mix the slag with the

reducing agent and perform the reduction and iron extraction to obtain the molten iron, iron

extraction slag and coal gas. Specifically, the reducing device 300 can include a reducing device

body 306, a reducing agent spray lance 307, a second fuel spray lance 308, a carburizing agent

spray lance 309 and a heat supplementing device 310. The reducing device body 306 is provided

with a reducing region 3061, a carburizing region 3062 and a settling region 3063 along a

horizontal direction, wherein a partition wall 3064 is arranged between the carburizing region

3062 and the settling region 3063. A bottom end of the partition wall 3064 is spaced apart from

a bottom of the reducing device body 306 by a distance. The slag inlet 301, the reducing agent

spray lance 307 and the second fuel spray lance 308 are all arranged in the reducing region

3061, and the end of the reducing agent spray lance 307 and the end of the second fuel spray

lance 308 extend below the slag layer 3066 of the reducing region 3061. The reducing agent

spray lance 307 is provided with a reducing agent inlet 302. The carburizing agent spray lance

309 is arranged in the carburizing region 3062, and the end of the carburizing agent spray lance

309 extend below the slag layer 3066 of the reducing region 3062. The heat supplementing

device 310 is arranged in the carburizing region 3062 and the settling region 3063. The molten

iron outlet 303 is arranged in the molten iron layer 3065 of the settling region 3063; the iron

extraction slag outlet 304 is arranged in the slag layer 3066 of the settling region 3063; and the

slag inlet 301 can be connected with the slag outlet 202 through a launder (not shown). High

temperature slag at about 1500°C is continuously added into the reducing region 3061 of the

reducing device body 306 through the launder, and the oxygen-enriched air and the fuel enter

below the slag layer 3066 of the reducing region 3061 by the second fuel spray lance 308 for

submerged combustion. Specific chemical reaction equations include

CaHbOcNSe+02--CO+H20+N2+SO2, and CO+02-CO2t. The reducing agent is sprayed

below the slag layer 3066 of the reducing region 3061 by the reducing agent spray lance 307, mixed with the high-temperature slag and subjected to reduction and iron extraction at 1400°C to 1500°C. In the presence of the reducing agent, iron oxides in the slag are reduced into metallic iron to obtain the molten iron, iron extraction slag and coal gas, and the specific chemical reaction equations include Fe30 4+CO--*FeO+CO2T, FeO+C--*Fe+COt, and CaO+SiO2-2CaO-SiO2. The obtained molten iron and iron extraction slag flow into the carburizing region 3062. The molten iron will gradually settle at the bottom of the furnace due to relatively high density, so it will be separated from the iron extraction slag so as to form the molten iron layer 3065 and the slag layer 3066. The airflow ejected from the carburizing agent spray lance 309 can blow the carburizing agent into the molten iron layer 3065 to increase the carburizing efficiency. The molten iron and partial iron extraction slag in the carburizing region 3062 can pass under the partition wall 3064 and flow into the settling region 3063, and the partition wall 3064 can decrease the fluctuation of the settling region 3063, which is conductive to improve the separation effect of the molten iron from the iron extraction slag. In the reduction and iron extraction process, heat can be supplemented by the heat supplementing device 310. The molten iron in the settling region 3063 is discharged from the molten iron outlet 303 and can be used for steelmaking, thereby realizing comprehensive utilization of the iron element in the lateritic nickel ore leaching tailings. The iron extraction slag is discharged from the iron extraction slag outlet 304 and may be used as a raw building material after being subjected to water fragmentation. The obtained coal gas is discharged from the coal gas outlet 305. Moreover, because of more heat is required for melting and slagging desulfurization and less heat is required for reduction and iron extraction, it can reduce the energy consumption and decrease production and operation cost by performing the operations of melting and slagging desulfurization and reduction and iron extraction in different apparatuses, respectively.

[0081] According to the embodiments of the present disclosure, for reduction and iron extraction, the CaO-SiO2-MgO-Al203 slag system can be used. By adding the flux in the preheating process, the mass ratio of CaO to SiO 2 in the iron extraction slag is controlled to be (0.9-1.2):1, and content of MgO in the iron extraction slag is controlled to range from 6 wt% to 10 wt%, and the viscosity of the iron extraction slag is less than 0.8 Pa-s at 1450°C, having very good fluidity. Specifically, the retention time of the iron extraction slag in the settling region 3043 is >30 min to reduce the iron content; the discharge temperature of the molten iron can be

1400°C to 1500°C; and the discharge temperature of the iron extraction slag can be 1450°C to

1550 0 C.

[0082] According to the embodiments of the present disclosure, the reducing device body 306 can be a melt pool smelting furnace; the furnace bottom is an adiabatic structure; the

furnace wall at a position of the molten iron layer 3065 is of a refractory material structure; the

slag layer 3066 and the furnace wall above the slag layer 3066 are of a waterjacket embedded

refractory brick structure; and the partition wall 3064 can be a water-cooled wall. Moreover,

the reducing device body 306 can be maintained at a slight positive pressure, thereby avoiding

a condition that purity of the coal gas is decreased due to excessive air leakage.

[0083] According to the embodiments of the present disclosure, the end of the second fuel

spray lance 308 is spaced apart from the top of the slag layer 3066 by a distance not less than

200 mm, and the second fuel spray lance is located above the molten iron layer; for the second

fuel spray lance, high calorific value fuels such as pulverized coal, natural gas, and fuel oil can

be used; the combustion-supporting air used may include oxygen-enriched air with the

concentration of oxygen not less than 65 vol%; and an excess air coefficient is controlled so

that the volume of CO in the reaction system accounts for not less than 80% of the total volume

of CO and C02, thereby increasing a reduction effect and reducing the iron content of the iron

extraction slag. The reducing agent can be anthracite or coke fines, the particle size of which

can be 2 mm to 5 mm and the fixed carbon content is >70%, and the amount of the reducing

agent for producing each ton of the molten iron is not less than 300 kg. For the carburizing

agent, anthracite or coke fines can be used.

[0084] According to the embodiments of the present disclosure, a heat supplementing

device 310 may include a third fuel spray lance and/or an electrode. When the heat is

supplemented by the third fuel spray lance, the end of the third fuel spray lance extend below

the slag layer 3066, and the oxygen-enriched air and the fuel enter below the slag layer 3066

by the third fuel spray lance for submerged combustion to provide heat for the reduction and

iron extraction; and when the heat is supplemented by the electrode, the end of the electrode

extend below the slag layer 3066 to provide heat for the reduction and iron extraction.

Specifically, for the third fuel spray lance, high calorific value fuels such as pulverized coal,

natural gas, and fuel oil can be used; the combustion-supporting air used may include oxygen- enriched air having the concentration of oxygen not less than 65 vol%; and in addition, the inventors have found that, the excess air coefficient is controlled so that the volume of CO in the reaction system accounts for not less than 80% of the total volume of CO and C02, which can improve the reduction effect and reduce the iron content of the iron extraction slag.

[0085] According to the embodiments of the present disclosure, referring to Fig. 9, the system further includes a pre-drying treatment device 400 and a first dust collecting device (not shown). The pre-drying treatment device 400 is provided with a lateritic nickel ore leaching tailings inlet 401, a dried leaching tailing outlet 402 and a pre-dried tail gas outlet 403, wherein the dried leaching tailing outlet 402 is connected with the lateritic nickel ore leaching tailings inlet 401, and the pre-dried tail gas outlet 403 is connected with the first dust collecting device. Moreover, the pre-drying treatment device is adapted to perform the pre-drying treatment on the lateritic nickel ore leaching tailings in advance before the lateritic nickel ore leaching tailings are mixed with the flux. Specifically, the water content of the tailings after filter pressing in the lateritic nickel ore wet leaching system ranges from 30 wt% to 45 wt%; and the tailings are fed into the pre-drying treatment device 400 via the lateritic nickel ore leaching tailings inlet 401, so that part of the water in the tailings after filter pressing in the lateritic nickel ore wet leaching system can be removed to obtain the lateritic nickel ore leaching tailings with water content of 15 wt% to 20 wt%. The lateritic nickel ore leaching tailings with water content of 15 wt% to 20 wt% are neither dusty nor clumped, which is conducive to the subsequent distribution and transportation. The tail gas produced in the pre-drying treatment enters the first dust collecting device via the pre-dried tail gas outlet 403 for evacuation after dust removal.

[0086] According to the embodiments of the present disclosure, for the pre-drying treatment device 400, a steam drier or a rotary drying kiln can be used. When the steam drier is used, the pre-drying treatment device 400 can be connected with a flue gas waste heat recovery device 21, a heat exchange mode is indirect heat exchange, a heat source can be the steam generated in the process of waste heat recovery of the flue gas that is obtained by the melting and slagging desulfurization device 200, and the temperature is 120°C; and when the rotary drying kiln is used, a direct heat exchange is conducted, a concurrent drying kiln is preferred, the hot air temperature is <700°C, the tail gas temperature ranges from 105 to 120°C, and the first dust collecting device can be a bag dust collector.

[0087] According to the embodiments of the present disclosure, referring to Fig. 10, the above system further includes a drying and crushing device 500. The drying and crushing

device 500 is provided with an inlet 501 for a material to be treated and an outlet 502 for a dried

and crushed material, wherein the inlet 501 for the material to be treated is connected with a

mixed material outlet 103, and the outlet 502 for the dried and crushed material is connected

with a mixed material inlet 201. Moreover, the drying and crushing device 500 is adapted to

dry and crush the mixed material in advance before the mixed material is supplied to the melting

and slagging desulfurization device 200, and supply the obtained dried and crushed mixed

material to the melting and slagging desulfurization device 200. Specifically, the drying and

crushing device 500 may include a drying and crushing device body (not shown), a powder

pneumatic lifting device (not shown) and a second dust collecting device (not shown) which

are connected in sequence. The drying and crushing device body is provided with the inlet 501

for a material to be treated; the second dust collecting device is provided with the outlet 502 for

a dried and crushed material; the mixed material enters the drying and crushing device body via

the inlet 501 for material to be treated, is crushed under the action of a mechanical force, and is

rapidly uniformly mixed and dried by hot air. The dried and crushed mixed material is fed into

the second dust collecting device by the powder pneumatic lifting device to be collected to

obtain the dried and crushed mixed material; and the mixed material collected in the second

dust collecting device is dried and crushed and then fed to the melting and slagging

desulfurization device 200 via the outlet 502 for the dried and crushed material. Therefore, the

particle size of the mixed material can be decreased, a specific surface area of the mixed

material is increased, free water in the mixed material is removed, and partial gypsum in the

lateritic nickel ore leaching tailings is dehydrated into semi-hydrated gypsum and CaSO 4

(CaSO 4 -2H20--CaSO 4 -0.5H2 0+H 207, and CaSO 4 -0.5H20--CaSO4 +H20t), thereby

increasing the efficiency of subsequent melting and slagging desulfurization and reducing

energy consumption of the chemical material. Meanwhile, the mixed material can be

homogenized, which is beneficial to the reduction and iron extraction.

[0088] Specifically, the hot air used by the drying and crushing device can be at a

temperature of 600°C to 800°C; the tail gas temperature of the second dust collecting device

can be 120°C to 150°C; an air-charge ratio is more than and equal to 200 Nm 3/t (the specific

')'7 amount is obtained by the thermal equilibrium calculation according to the water content of the mixed material and the hot air temperature); and an airflow velocity of the powder pneumatic lifting device can be 4 m/s to 10 m/s, thereby avoiding a too high dust rate due to a too low particle size of the dried slag or large pipeline wear, high system resistance and high energy consumption caused by a too high particle size of the dried slag. The retention time of the material in the pneumatic lifting device is not less than 2s, and the water content of the dried and crushed mixed material is not more than 2 wt% and the particle size is not more than 2 mm.

[0089] It should be noted that, the specific types of the drying and crushing device body, the powder pneumatic lifting device and the second dust collecting device can be selected by those skilled in the art according to actual needs. For example, the drying and crushing device body may be a ball mill, a vertical mill, an air swept mill or a hammer crusher and any other apparatus with both crushing and drying functions; the powder pneumatic lifting device can be a pneumatic lifting pump; and the second dust collecting device can be a bag dust collector.

[0090] According to the embodiments of the present disclosure, referring to Fig. 11, the system further includes a preheating device 600 and a third dust collecting device 61. The preheating device 600 is provided with a mixed material inlet 601, a preheated material outlet 602, and a preheated tail gas outlet 603, wherein the mixed material inlet 601 is connected with the mixed material outlet 103, and the preheated material outlet 602 is connected with the mixed material inlet 201. The preheating device is adapted to: preheat the mixed material in advance before the mixed material is supplied to the melting and slagging desulfurization device 200, and supply the obtained preheated mixed material to the melting and slagging desulfurization device 200. The third dust collecting device 61 is provided with a preheated tail gas inlet 611, a dust collecting outlet 612 and an outlet for tail gas outlet after dust collection 613, wherein the preheated tail gas inlet 611 is connected with the preheated tail gas outlet 603, the dust collecting outlet 612 is connected with the mixed material inlet 601, and the outlet for tail gas outlet after dust collection 613 is connected with the pre-drying treatment device 400. Specifically, the mixed material is fed into the preheating device 600 via the mixed material inlet 601, so that it can be rapidly preheated and decomposed, and the temperature is appropriately raised to obtain the preheated mixed material and preheated tail gas. Specific chemical reaction equations include: CaSO 4 -2H20--CaSO 4+H207,

CaSO 4 -0.5H 20--CaSO 4+H 2 0T, Fe(OH)3--Fe2O3+H20t, Al(OH) 3-- A 20 3+H 207,

Ca(OH)2--CaO+H207, and CaMgC20 6 -- CaCO3+MgO+H20t. The obtained preheated mixed

material is fed to the melting and slagging desulfurization device 200 via the preheated material

outlet 602, thereby increasing the efficiency of subsequent melting and slagging desulfurization

and reducing energy consumption of the chemical material. The obtained preheated tail gas

enters the third dust collecting device 61 via the preheated tail gas inlet 611 for dust removal to

obtain the dust-collected tail gas and flue after dust collection, and the obtained tail gas after

dust collection is fed into the pre-drying treatment device 400 via the outlet for tail gas after

dust collection 613 to serve as a heat source of the pre-drying treatment device, which can

realize full utilization of the waste heat, thereby reducing the energy consumption. The obtained

smoke dust returns to the preheating device 600 via the dust collecting outlet 612, thereby

increasing a resource utilization rate of the lateritic nickel ore leaching tailings. According to

one specific embodiment of the present disclosure, referring to Fig. 12, the mixed material inlet

601 can be connected with the outlet for the dried and crushed material 502, and thus the dried

and crushed mixed material is further preheated, thereby increasing the efficiency of subsequent

melting and slagging desulfurization and reducing the energy consumption of the chemical

material.

[0091] According to the embodiments of the present disclosure, the third dust collecting device 61 can be an electric dust collector; the preheating device 600 can be a cyclone preheater;

a preheating mode can be countercurrent heat exchange; an heat source used can be the hot air

of 700-800°C generated in the waste heat recovery process by the flue gas containing S02 that

is obtained by melting and slagging desulfurization; the temperature of the obtained preheated

tail gas iss200°C; and the temperature of the preheated mixed material can be 500°C to 650°C.

It should be noted that, the stages of the cyclone preheater can be selected by those skilled in

the art according to actual needs, for example, 3 to 5 stages.

[0092] According to the embodiments of the present disclosure, referring to Fig. 13, the system further includes a coal gas utilization device 31. The coal gas utilization device 31 is

connected with the coal gas outlet 305, the pre-drying treatment device 400, the preheating

device 600 and the melting and slagging desulfurization device 200, and is adapted to collect

and supply the coal gas generated in the reducing device, as fuel, to at least one of the pre drying treatment device 400, the preheating device 600 and the melting and slagging desulfurization device 200. Specifically, the coal gas utilization device 31 can include a coal gas waste heat boiler (not shown), a cooling dust collecting device (not shown), a pressurization fan (not shown) and a coal gas storage tank (not shown) which are connected in sequence. The coal gas discharged out of the coal gas outlet 305 is collected under a negative pressure, cooled to about 850°C to 1000°C through the coal gas waste heat boiler, and then quenched to below

200°C by the cooling dust collecting device to obtain clean coal gas. The quenched coal gas is

pressurized by the fan, then fed into the coal gas storage tank, and can be used as fuel for the

pre-drying treatment device 400, the preheating device 600 and the melting and slagging

desulfurization device 200. The steam generated by the coal gas waste heat boiler can be used

to pre-dry the tailings after filter pressing in the lateritic nickel ore wet leaching system. Thus,

the coal gas utilization efficiency (compared with conventional coal gas power generation) and

the heat utilization rate of the whole process can be increased, thereby reducing the energy

consumption.

[0093] It should be noted that, the soot generated by the system can also be mixed with the

lateritic nickel ore leaching tailings and the flux for the melting and slagging desulfurization

and conduct reduction and iron extraction, thereby further increasing the resource utilization

rate of the lateritic nickel ore leaching tailings.

[0094] Therefore, the system for resource utilization of lateritic nickel ore leaching tailings disclosed by the present disclosure not only can solve the problem of environmental protection

hazards of the lateritic nickel ore leaching tailings, but also can comprehensively utilize

valuable elements therein such as iron and sulfur and produce considerable economic benefits,

and is low in energy consumption and low in production cost. Moreover, by performing the

operations of pre-drying, drying and crushing, preheating, melting and slagging desulfurization,

and reduction and iron extraction in different apparatuses, respectively; the advantages of the

various stages are fully utilized; the steam generated by waste heat recovery in the operations

of melting and slagging desulfurization and reduction and iron extraction or the tail gas in the

preheating process is used for pre-drying; and the coal gas generated in the reduction and iron

extraction is used for drying and crushing, preheating and melting and slagging desulfurization,

thereby achieving high-efficiency utilization of the coal gas (compared with the conventional coal gas power generation). It should be noted that, the system can also be used to produce nickel iron from the lateritic nickel ore, thereby replacing a rotary kiln electric furnace (RKEF) technology.

[0095] The present disclosure is described below with reference to the specific examples. It should be noted that, these examples are merely descriptive, rather than limiting the present disclosure in any way.

[0096] Example 1

[0097] 20 t of tailings after filter pressing in the lateritic nickel ore wet leaching system (the water content in wet basis was 35 wt%, the components of the dry basis were: 5.1 wt% of Ca, 32.5 wt% of Fe, 7.2 wt% of S, 6.0 wt% of Si and 2.5 wt% of Al) were dried by a steam drier

until the water content was 18% to obtain 15.85 t of lateritic nickel ore leaching tailings, and 4.55 t of saturated steam at 180°C was consumed. The lateritic nickel ore leaching tailings was neither dusty or clumped.

[0098] 200 kg/h of the lateritic nickel ore leaching tailings, 5.1 kg/h of limestone powder, 32.8 kg/h of dolomite powder and 4.9 kg/h of soot were added into the drying and crushing device, and 166 Nm 3/h of hot air at 700°C was introduced for drying for 2.5 s to obtain 208.3 kg/h of dried tailings with water content of 1.8% (that is, the dried and crushed mixed material).

[0099] The 208.3 kg/h of dried tailings were added into the preheating device for preheating, and 153.3 Nm3/h of heat exchange hot air at 750°C generated by the melting and slagging desulfurization device, 6.6 kg/h of pulverized coal and 143.8 Nm 3/h of combustion-supporting air were introduced to obtain 194.6 kg/h of hot calcine at 600°C (that is, the preheated mixed material).

[00100] The 194.6 kg/h of hot calcine, 36.8 Nm3/h of oxygen-enriched air (containing 70 vol% of 02) and 114.2 Nm3/h of coal gas were sprayed into a position 200 mm below the melt

pool surface (that is, the top of a slag melting region) in the melting and slagging desulfurization device; the excess air coefficient was controlled to be 0.97; a melting temperature was controlled to be 1500°C; a depth of the melt pool (that is, the distance between the top of the slag melting region and the bottom of the melting and slagging desulfurization device body) was controlled to be 900 mm. The hot calcine underwent the reactions of decomposition, desulfurization, melting and slagging under the action of combustion heat; and 143.6 kg/h of

'21 high-temperature slag was produced, including the following components in mass fraction: 34.4% of TFe, 16.3% of CaO, 15.8% of SiO 2 , 6.9% of Al203, 5.2% of MgO and 0.1% of S and has excellent fluidity. In addition, 39.2 Nm 3/h of secondary air was blown into a furnace wall to obtain 178.6 Nm 3/h of high-temperature flue gas at 1450°C (containing 3.0 vol% of 02 and 4.1 vol% of SO2 ), and the flue gas was cooled to about 1150°C by the flue gas waste heat boiler and cooled to about 180°C by utilizing a flue gas heat exchanger, and then fed to an acid making system to obtain 153.3 Nm 3/h of hot air at about 750°C (which is used for preheating the dried tailings).

[00101] The 143.6 kg/h of high-temperature slag was added into a reducing region of the reducing device body via a launder. In addition, 16.2 kg/h of anthracite was added by a reducing

agent spray lance, and 38.2 kg/h of bituminous coal and 54.4 Nm3/h of combustion-supporting

air (containing 70 Vol% of 02) were blown in by the second fuel spray lance. The high

temperature slag that flowed into the reducing device body reacted with the added reducing

agent at 1400°C to1450°C, wherein iron oxides were reduced into metallic iron and carburized.

The slag iron settled and was separated in the settling region; the settling time was >30 min; the

power consumption in the settling region was 11.2 kW; a discharge temperature of the molten

iron was about 1450°C; a discharge temperature of the iron extraction slag was about 1500°C;

and both the molten iron and the iron extraction slag had excellent fluidity. 47.9 kg/h of molten

iron (grade of 94.6%, containing 0.2% of S and 4.0% of C) and 86.9 kg/h of iron extraction slag

(the content of Fe was 5.5 wt%, a mass ratio of CaO to SiO2 was 1.0, the content of MgO was

8.4 wt%, the content of Al203 was 12.8 wt%, and the viscosity at 1450°C was less than 0.8 Pa-s)

were obtained.

[00102] The coal gas obtained by the reducing device was cooled to about 850°C by the coal

gas waste heat boiler, quenched to about 180°C, and then used for preheating after dust removal

and pressurization to obtain 122.1 Nm3/h of coal gas (51.2 vol% of CO and 9.6 vol% ofH 2 ).

[00103] The recovery rate of sulfur was 97.8%, the comprehensive recovery rate of Fe was

92.3%, and the coal consumption per ton of iron was 1.3 kg/t (including 337 kg/t of anthracite

and 935 kg/h of bituminous coal) during the process for treating the lateritic nickel ore leaching

tailings.

[00104] Example 2

[00105] 200 kg/h of the dried lateritic nickel ore leaching tailings in example 1 and 39.5 kg/h of dolomite powder were added into the drying and crushing device, and 205.1 Nm 3/h of hot

air at 600°C was introduced for drying for 2.5 s to obtain 210 kg/h of dried tailings with water

content of 1.5% (that is, the dried and crushed mixed material).

[00106] The 210 kg/h of dried tailings were added into the preheating device for preheating, and 217.9 Nm3/h of heat exchange hot air at 700°C generated by the melting and slagging

desulfurization device, 3.3 kg/h of pulverized coal and 94.4 Nm 3/h of combustion-supporting

air were introduced to obtain 195.6 kg/h of hot calcine at 500°C (that is, the preheated mixed

material).

[00107] The 195.6 kg/h of hot calcine, 56.8 Nm3/h of oxygen-enriched air (containing 65

vol% of 02), 10 kg/h of bituminous coal and 112.4 Nm 3/h of coal gas were sprayed into a

position 200 mm below the melt pool surface (that is, the top of a slag melting region) in the

melting and slagging desulfurization device; the excess air coefficient was controlled to be 0.95;

a melting temperature was controlled to be 1500°C; a depth of the melt pool (that is, the distance

between the top of the slag melting region and the bottom of the melting and slagging

desulfurization device body) was controlled to be 800 mm. The hot calcine underwent the

reactions of decomposition, desulfurization, melting and slagging under the action of

combustion heat; and 144.8 kg/h of high-temperature slag was produced, including the

following components in mass fraction: 34.2% of TFe, 15.9% of CaO, 15.8% of SiO 2 , 7% of

A12 0 3 , 6% of MgO and 0.1% of S and had excellent fluidity. In addition, 71.9 Nm3/h of

secondary air was blown into a furnace wall to obtain 236.2 Nm3/h of high-temperature flue

gas at 1445°C (containing 4.0 vol% of 02 and 3.1 vol% of SO 2 ), and the flue gas was cooled to

about 1150°C by the flue gas waste heat boiler and cooled to about 180°C by utilizing a flue

gas heat exchanger, and then fed to an acid making system to obtain 217.9 Nm 3/h of hot air at

about 700°C (which is used for preheating the dried tailings).

[00108] The 144.8 kg/h of high-temperature slag was added into a reducing region of the

reducing device body via a launder. In addition, 16.3 kg/h of anthracite was added by a reducing

agent spray lance, and 32.4 kg/h of bituminous coal and 52.4 Nm3/h of combustion-supporting

air (containing 65 Vol% of 02) were blown in by the second fuel spray lance. The high

temperature slag that flowed into the reducing device body reacted with the added reducing

'21 agent at 1400-1450°C, wherein iron oxides were reduced into metallic iron and carburized. The slag iron was settled and separated in the settling region; the settling time was >30 min; the power consumption in the settling region was 14.1 kW; a discharge temperature of the molten iron was about 1480°C; a discharge temperature of the iron extraction slag was about 1550°C; and both the molten iron and the iron extraction slag had excellent fluidity. 47.6 kg/h of molten iron (grade of 94.2%, containing 0.1% of S and 4.5% of C) and 88.3 kg/h of iron extraction slag (the content of Fe was 6.0 wt%, a mass ratio of CaO to SiO 2 was 0.9, the content of MgO was 9.8 wt%, the content of Al203 was 12.7 wt%, and the viscosity at 1450°C was less than 0.8 Pa-s) were obtained.

[00109] The coal gas obtained by the reducing device was cooled to about 850°C by the coal gas waste heat boiler, then was quenched to about 180°C, and used for preheating and immersion melting after dust removal and pressurization to obtain 112.4 Nm3/h of coal gas (47.2 vol% of CO and 8.2 vol% ofH 2 ).

[00110] The recovery rate of sulfur was 98.1%, the comprehensive recovery rate of Fe was 9 1. 2 %, and the coal consumption per ton of iron was 1.3 kg/t (including 343 kg/t of anthracite and 959 kg/h of bituminous coal during the process for treating the lateritic nickel ore leaching tailings).

[00111] Example 3

[00112] 200 kg/h of the dried lateritic nickel ore leaching tailings in example 1, 22.5 kg/h of limestone powder and 25.3 kg/h of dolomite powder were added into the drying and crushing device, and 141.1 Nm 3/h of hot air at 800°C was introduced for drying for 2.5 s to obtain 218 kg/h of dried tailings with water content of 1. 9 5 %(that is, the dried and crushed mixed material).

[00113] The 218 kg/h of dried tailings were added into the preheating device for preheating, and 102.6 Nm3/h of heat exchange hot air at 800°C generated by the melting and slagging desulfurization device, 30.7 Nm3/h of coal gas and 149.8 Nm 3/h of combustion-supporting air were introduced to obtain 204.2 kg/h of hot calcine at 650°C (that is, the preheated mixed material).

[00114] The 204.2 kg/h of hot calcine, 27.5 Nm3/h of oxygen-enriched air (containing 80 Vol% of 02) and 86.7 Nm3/h of coal gas were sprayed into a position 200 mm below the melt pool surface (that is, the top of a slag melting region) in the melting and slagging desulfurization device; the excess air coefficient was controlled to be 0.98; a melting temperature was controlled to be 1500°C; a depth of the melt pool (that is, the distance between the top of the slag melting region and the bottom of the melting and slagging desulfurization device body) was controlled to be 1000 mm; the hot calcine underwent the reactions of decomposition, desulfurization, melting and slagging under the action of combustion heat; and 149.4 kg/h of high-temperature slag was produced, including the following components in mass fraction: 33.1% of TFe, 19.8% of CaO, 15.4% of Si0 2 , 6.5% of A1 2 0 3 , 3.9% of MgO and 0.1% of S and had excellent fluidity. In addition, 19.4 Nm 3/h of secondary air was blown into a furnace wall to obtain 129 Nm3/h of high-temperature flue gas at 1475°C (containing 2.0 vol% of 02 and 5.6 vol% of SO2 ), and the flue gas was cooled to about 1150°C by the flue gas waste heat boiler and cooled to about 180°C by utilizing a flue gas heat exchanger, and then fed to an acid making system to obtain 102.6 Nm 3/h of hot air at about 800°C (which is used for preheating the dried tailings).

[00115] The 149.4 kg/h of high-temperature slag was added into a reducing region of the reducing device body via a launder. In addition, 16.1 kg/h of anthracite was added by a reducing agent spray lance, and 44.2 kg/h of bituminous coal and 52.4 Nm3/h of combustion-supporting air (containing 80 Vol% of 02) were blown in by the second fuel spray lance. The high temperature slag that flowed into the reducing device body reacted with the added reducing agent at 1400°C to 1450°C, wherein iron oxides were reduced into metallic iron and carburized. The slag iron was settled and separated in the settling region; the settling time was >30 min; the power consumption in the settling region was 8.5 kW; a discharge temperature of the molten iron was about 1410°C; a discharge temperature of the iron extraction slag was about 1450°C; and both the molten iron and the iron extraction slag had excellent fluidity. 48.1 kg/h of molten iron (grade of 94.9%, containing 0.2% of S and 3.7% of C) and 92.8 kg/h of iron extraction slag

(the content of Fe was 5.0 wt%, a mass ratio CaO to Si02 was 1.2, the content of MgO was 6.3 wt%, the content of A12 0 3 was 11.9 wt%, and the viscosity at 1450°C was less than 0.8 Pa-s) were obtained.

[00116] The coal gas obtained by the reducing device was cooled to about 850°C by the coal gas waste heat boiler, quenched to about 180°C, and then used for preheating and immersion melting after dust removal and pressurization to obtain 128.2 Nm3/h of coal gas (56.7 vol% of

CO and 11.3 vol% ofH2).

[00117] The recovery rate of sulfur was 97.4%, the comprehensive recovery rate of Fe was 92.9%, and the coal consumption per ton of iron was1.3 kg/t (including 335 kg/t of anthracite

and 920 kg/h of bituminous coal) during the process for treating the lateritic nickel ore leaching

tailings

[00118] It can be seen from examples 1 to 3 that, the method for resource utilization of lateritic nickel ore leaching tailings disclosed by the present disclosure not only can solve the

problem of environmental protection hazards of the lateritic nickel ore leaching tailings, but

also can comprehensively utilize valuable elements therein such as iron and sulfur to produce

considerable economic benefits, and is low in energy consumption, low in production cost,

simple in process, easy to operate, suitable for mass production and extremely high in practical

value.

[00119] In the description of this specification, the description referring to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples", etc.

means that specific features, structures, materials or characteristics described in combination

with the embodiment or example are included in at least one embodiment or example of the

present disclosure. In this description, the schematic expressions for the above terms are not

necessarily aimed at the same embodiment or example. Moreover, the described specific

features, structures, materials or characteristics can be combined appropriately in any one or

more embodiments or examples. In addition, those skilled in the art can combine and integrate

different embodiments or examples and features of different embodiments or examples

described in this description without contradicting each other.

[00120] Although the embodiments of the present disclosure have been shown and described

above, it will be appreciated that the above embodiments are exemplary and shall not be

understood as limitations to the present disclosure. Those ordinary skilled in the art can make

changes, modifications, replacements and variations to the above embodiments within the scope

of the present disclosure.

Claims (24)

1. What is claimed is: 1. A method for resource utilization of lateritic nickel ore leaching tailings, comprising:

   (1) mixing the lateritic nickel ore leaching tailings with a flux to obtain a mixed material;

   (2) performing a melting and slagging desulfurization on the mixed material to obtain slag

   and flue gas containing SO 2 ; and

   (3) mixing the slag with a reducing agent for reduction and iron extraction to obtain molten

   iron, iron extraction slag, and coal gas.
2. 2. The method according to claim 1, wherein the lateritic nickel ore leaching tailings are

   pre-dried prior to said mixing the lateritic nickel ore leaching tailings with the flux.
3. 3. The method according to claim 1 or 2, wherein in step (1), drying and crushing are

   performed subsequent to said mixing the lateritic nickel ore leaching tailings with the flux.
4. 4. The method according to any one of claims I to 3, wherein in step (1), the flux comprises

   CaO and MgO.
5. 5. The method according to any one of claims 1 to 4, wherein the lateritic nickel ore

   leaching tailings and the flux are mixed at a ratio enabling a mass ratio of CaO to SiO 2 in the

   iron extraction slag to be (0.9-1.2): 1 and a content of MgO in the iron extraction slag to be 6

   wt% to 10 wt%.
6. 6. The method according to any one of claims I to 5, wherein in step (2), a temperature of

   the melting and slagging desulfurization ranges from 1500°C to 1550°C.
7. 7. The method according to any one of claims 1 to 6, wherein ends of a first fuel spray

   lance and a mixed material spray lance extend below the slag during the melting and slagging

   desulfurization.
8. 8. The method according to any one of claims 1 to 7, wherein combustion-supporting air

   adopted by the first fuel spray lance comprises oxygen-enriched air, a concentration of oxygen

   in the oxygen-enriched air being not less than 65 vol%, and an excess air coefficient ranging

   from 0.95 to 0.98.
9. 9. The method according to any one of claims 1 to 8, wherein in step (3), a temperature of

   '1 7 reduction and iron extraction ranges from 1400°C to 1500°C.
10. 10. The method according to any one of claims 1 to 9, wherein an end of a second fuel

    spray lance extends below a slag layer during the reduction and iron extraction.
11. 11. The method according to any one of claims 1 to 10, wherein the reduction and iron

    extraction is supplemented with heat by a third fuel spray lance and/or an electrode.
12. 12. The method according to any one of claims 1 to 11, wherein when the reduction and

    iron extraction is supplemented with heat by a third fuel spray lance, the end of the third fuel

    spray lance extends below a slag layer, and a volume of CO in a reaction system accounts for

    not less than 80% of a total volume of CO and C02.
13. 13. The method according to any one of claims 1 to 12, wherein the mixed material is pre

    heated prior to said performing the melting and slagging desulfurization on the mixed material.
14. 14. The method according to any one of claims 1 to 13, wherein a temperature of a

    preheated mixed material ranges from 500°C to 650°C.
15. 15. A system for resource utilization of lateritic nickel ore leaching tailings, comprising:

    a mixing device having an inlet for the lateritic nickel ore leaching tailings, a flux inlet,

    and, a mixed material outlet, the mixing device being adapted to mix the lateritic nickel ore

    leaching tailings with a flux to obtain a mixed material;

    a melting and slagging desulfurization device having a mixed material inlet, a slag outlet

    and a flue gas outlet, the mixed material inlet being connected with the mixed material outlet,

    and the melting and slagging desulfurization device being adapted to perform a melting and

    slagging desulfurization on the mixed material to obtain slag and flue gas containing SO 2 ; and

    a reducing device having a slag inlet, a reducing agent inlet, a molten iron outlet, an iron

    extraction slag outlet, and a coal gas outlet, the slag inlet being connected with the slag outlet,

    and the reducing device being adapted to mix the slag with a reducing agent for reduction and

    iron extraction to obtain molten iron, iron extraction slag, and coal gas.
16. 16. The system according to claim 15, further comprising a pre-drying treatment device,

    wherein:

    the pre-drying treatment device has a lateritic nickel ore leaching tailings inlet and a dried

    leaching tailings outlet connected with the lateritic nickel ore leaching tailings inlet; and

    the pre-drying treatment device is adapted to pre-dry the lateritic nickel ore leaching tailings before the lateritic nickel ore leaching tailings are mixed with the flux.
17. 17. The system according to claim 15 or 16, further comprising a drying and crushing

    device, wherein:

    the drying and crushing device has an inlet for a material to be treated and an outlet for a

    dried and crushed material, the inlet for the material to be treated being connected with the

    mixed material outlet, and the outlet for the dried and crushed material being connected with

    the mixed material inlet; and

    the drying and crushing device is adapted to dry and crush the mixed material before the

    mixed material is supplied to the melting and slagging desulfurization device; and supply the

    dried and crushed mixed material to the melting and slagging desulfurization device.
18. 18. The system according to any one of claims 15 to 17, further comprising:

    a preheating device having a mixed material inlet, a preheated material outlet, and a

    preheated tail gas outlet, the mixed material inlet being connected with the mixed material outlet,

    the preheated material outlet being connected with the mixed material inlet, and the preheating

    device being adapted to: preheat the mixed material before the mixed material is supplied to the

    melting and slagging desulfurization device; and supply the preheated mixed material to the

    melting and slagging desulfurization device; and

    a dust collecting device having a preheated tail gas inlet, a dust collecting outlet, and an

    outlet for tail gas after dust collection, the preheated tail gas inlet being connected with the

    preheated tail gas outlet, the dust collecting outlet being connected with the mixed material inlet,

    and the outlet for the tail gas after dust collection being connected with the pre-drying treatment

    device.
19. 19. The system according to any one of claims 15 to 18, wherein the melting and slagging

    desulfurization device comprises:

    a melting and slagging desulfurization device body comprising a furnace and a slag region

    from top to bottom;

    a mixed material spray lance having an end extending into the slag region;

    a first fuel spray lance having an end extending into the slag region;

    a secondary tuyere arranged on the furnace;

    a flue duct in communication with the furnace; and

    '20 a slag outlet arranged on a side wall of the slag region.
20. 20. The system according to any one of claims 15 to 19, wherein the melting and slagging

    desulfurization device further comprises a flue gas waste heat recovery device connected with

    the flue duct.
21. 21. The system according to any one of claims 15 to 20, wherein the reducing device

    comprises:

    a reducing device body having, along a horizontal direction, a reducing region, a

    carburizing region, and a settling region, a partition wall being arranged between the

    carburizing region and the settling region, and a bottom end of the partition wall being spaced

    apart from a bottom of the reducing device body by a distance;

    a slag inlet arranged in the reducing region;

    a reducing agent arranged in the reducing region;

    a second fuel spray lance arranged in the reducing region and having an end extending

    below the slag layer of the reducing region;

    a carburizing agent spray lance arranged in the carburizing region and having an end

    extending into the slag layer of the carburizing region; and

    a heat supplementing device arranged in the carburizing region and the settling region.
22. 22. The system according to any one of claims 15 to 21, further comprising a coal gas

    utilization device, wherein:

    the coal gas utilization device is connected with the coal gas outlet, the pre-drying

    treatment device, the preheating device, and the melting and slagging desulfurization device;

    and

    the coal gas utilization device is adapted to collect and supply the coal gas generated in

    the reducing device, as fuel, to at least one of the pre-drying treatment device, the preheating

    device and the melting and slagging desulfurization device.
23. 23. The system according to any one of claims 15 to 22, wherein:

    a top of the slag region is spaced apart from a bottom of the melting and slagging

    desulfurization device body by a distance not less than 800 mm;

    an end of the mixed material spray lance is spaced apart from the top of the slag region by

    a distance not less than 200 mm, and an end of the first fuel spray lance is spaced apart from the top of the slag region by a distance not less than 200 mm.
24. 24. The system according to any one of claims 15 to 23, wherein an end of the second fuel

    spray lance is spaced apart from the top of the slag layer by a distance not less than 200 mm

    and is located above a molten iron layer.

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