CN115627350A

CN115627350A - Method for combining high-phosphorus iron ore and stone coal

Info

Publication number: CN115627350A
Application number: CN202211653493.XA
Authority: CN
Inventors: 张�杰; 张文博; 闫柏军; 何杨; 刘建华; 苗庆东; 李明; 高官金
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 2022-12-22
Filing date: 2022-12-22
Publication date: 2023-01-20
Anticipated expiration: 2042-12-22
Also published as: CN115627350B

Abstract

The application provides a method for combining high-phosphorus iron ore and stone coal, and relates to the field of solid waste treatment. The method comprises the following steps: mixing raw materials including high-phosphorus iron ore, stone coal and a binder, pelletizing, drying, and then carrying out heating reduction reaction for dephosphorization to obtain a reduced pellet; carrying out induction heating on the reduced pellets, cooling, crushing and magnetically separating to obtain low-phosphorus metallic iron particles; or, carrying out electric furnace melting and separation on the reduced pellets, and accessing the reduced pellets into a short-flow steelmaking flow to obtain low-phosphorus molten iron; and the tailings obtained by magnetic separation and the tailings obtained by electric furnace melting separation are used for recovering vanadium. The method utilizes the advantage of oxides contained in the stone coal on the reduction of dephosphorization reaction, realizes high-efficiency dephosphorization under the low-temperature condition, and effectively prevents the problems of iron melting and phosphorus entering into the molten iron in large quantity caused by higher temperature in the traditional coal-based reduction process. Carbon in the solid waste stone coal is used as a reducing agent to replace coal coke, so that low-cost dephosphorization is realized; meanwhile, the oxidation of vanadium is realized, and conditions are provided for the subsequent vanadium extraction process.

Description

Method for combining high-phosphorus iron ore and stone coal

Technical Field

The application relates to the field of solid waste treatment, in particular to a method for combining high-phosphorus iron ore and stone coal.

Background

The resource of the high-phosphorus oolitic iron ore in China is very rich, 37.2 hundred million tons are explored at present, and new resource amount of hundreds of billions of tons can be expected to be explored in the future. However, in the ores, the iron mineral and the gangue mineral are in a structure of \38200particles, the embedded particle size is extremely small, the phosphorus content of harmful elements is high (phosphorus exists in apatite phase), the phosphorus content of directly smelted and discharged molten iron is very high and can reach more than 1wt%, and the requirements of subsequent smelting can hardly be met. Therefore, if the phosphorus in the ore can be effectively removed before smelting, the method has important significance for the high-efficiency utilization of the high-phosphorus iron ore and also has very important significance for the supply of the iron ore in China.

The existing dephosphorization technology of high-phosphorus iron ore mainly comprises a heavy ore dressing method, a roasting-magnetic separation method, a microbial reduction method, a direct leaching method, a direct reduction method and the like. Currently, coal-based direct reduction is the mainstream direction of research. However, if phosphorus in high phosphorus hematite exists in apatite phase, and carbon is added for reduction, from thermodynamic angle, the temperature needs to reach above 1400 ℃ to perform reduction reaction, at this time, iron is reduced and becomes liquid iron, and a large amount of reduced phosphorus enters into iron liquid, so that effective dephosphorization effect cannot be obtained. Therefore, the direct reduction of phosphorus in high-phosphorus iron ore by using coal coke cannot achieve the ideal dephosphorization effect. While adding other additives such as silicon dioxide and the like while adding the coal tar, the dephosphorization reaction can be carried out only when the temperature is more than 1100-1200 ℃, and a large amount of phosphorus enters into molten iron, so that the dephosphorization cannot be effectively carried out.

The high-carbon stone coal is a mineral with large inventory and difficult resource utilization in China. Vanadium in the stone coal is a main valuable element, the vanadium reserves are about 1.18 hundred million tons and account for 87 percent of the total reserves, so the stone coal can be used as one of main sources for obtaining the vanadium. At present, the stone coal is treated by an oxidation roasting-acid leaching method. The method takes the extraction of vanadium as the center of gravity in the process of treating the stone coal, not only can generate a large amount of carbon dioxide gas, waste acid and the like in the treatment process, but also seriously neglects the utilization of carbon resources in the stone coal. For example, in the blank roasting-acid leaching process, the method of directly roasting in an air atmosphere is adopted to destroy vanadium existing in mica mineral lattices so as to provide conditions for subsequent leaching of the vanadium. Although the method can realize vanadium leaching, the carbon resource in the stone coal is wasted by combustion, and only part of heat is provided.

Aiming at the comprehensive utilization of high phosphorus ore, more research works are made by predecessors. The available literature and patents show that the use of high-phosphorus iron ore as a raw material in an iron-making process aims to obtain qualified molten iron, regardless of the process ideas related to direct reduction (gas-based or coal-based reduction), smelting reduction, or reduction plus melting separation. However, all studies indicate that iron/phosphorus separation under reducing conditions is difficult and harsh. And because the temperature is too high in the reduction process, a large amount of phosphorus can be melted into the formed liquid iron, and the high-efficiency separation of iron and phosphorus cannot be realized. If the high-phosphorus iron ore is applied to the steel industry in a large scale, a method capable of realizing effective separation of iron/phosphorus at a lower temperature is urgently needed, so that metal iron can be obtained through magnetic separation or directly enters an electric furnace for melting.

In the process of utilizing the stone coal resources, vanadium is taken as a main line, but the utilization of carbon is ignored. In addition, the existing process needs a large amount of energy consumption, generates a large amount of greenhouse gases and the like, and cannot realize clean utilization.

Disclosure of Invention

The application aims to provide a method for combining high-phosphorus iron ore and stone coal so as to solve the problems.

In order to achieve the purpose, the following technical scheme is adopted in the application:

a method for combining high-phosphorus iron ore and stone coal comprises the following steps:

mixing raw materials including high-phosphorus iron ore, stone coal and a binder, pelletizing, drying, and then carrying out heating reduction reaction for dephosphorization to obtain a reduced pellet;

carrying out induction heating on the reduced pellets, cooling, crushing and carrying out magnetic separation to obtain low-phosphorus metallic iron particles; or, carrying out electric furnace melting and separation on the reduced pellets, and accessing the reduced pellets into a short-flow steelmaking flow to obtain low-phosphorus molten iron;

and the tailings obtained by the magnetic separation and the tailings obtained by the electric furnace melting separation are used for recovering vanadium.

Preferably, the high-phosphorus iron ore is pre-crushed to obtain particles with the particle size of 10 meshes or less, and the stone coal is pre-crushed to obtain particles with the particle size of 50 meshes or less.

Preferably, the mass ratio of the high-phosphorus iron ore to the stone coal to the binder is 100: (80-120): (1-5).

Preferably, the binder comprises bentonite and/or water glass, and the particle size is less than or equal to 200 meshes.

Preferably, the temperature of the heating reduction reaction is 800-1100 ℃, and the time is 20-250min;

the metallization rate of the reduced pellets is more than or equal to 90 percent.

Preferably, the maximum temperature of the induction heating is 1200 ℃ and the time is 10-20min.

Preferably, the material is crushed to an average particle size of 100 mesh or less after the cooling.

Preferably, the total iron content of the low-phosphorus metallic iron particles is more than or equal to 92wt%, and the phosphorus content is less than 0.1wt%.

Preferably, the temperature of the electric furnace melting is 1450-1550 ℃;

calcium oxide is added in the electric furnace melting process, and the proportion of the calcium oxide to the slag is 1: (0.4-0.6).

Preferably, the phosphorus content in the low-phosphorus molten iron is less than or equal to 0.1wt%.

Compared with the prior art, the beneficial effect of this application includes:

according to the method for combining the high-phosphorus iron ore and the stone coal, the high-phosphorus iron ore and the stone coal are combined, and the beneficial effect of oxides contained in the stone coal on reduction of dephosphorization reaction is utilized, so that efficient dephosphorization under the low-temperature condition is realized, and the problems of iron melting and mass phosphorus entering into molten iron caused by higher temperature in the traditional coal-based reduction process are effectively prevented; in addition, the stone coal is a solid waste, the carbon resource in the stone coal cannot be effectively utilized, vanadium is difficult to leach and extract, and high-energy-consumption and high-pollution processes such as roasting, acid leaching and the like are needed; the method utilizes carbon in the stone coal as a reducing agent, reduces the using amount of the coal coke and realizes low-cost dephosphorization; meanwhile, vanadium in tailings is separated and oxidized from the original crystal lattice, conditions are provided for subsequent wet leaching, and the effect of '1 +1 > 2' is really realized. The reduced iron particle size after low-temperature dephosphorization is very small, and the dispersed iron particles can be induced to grow up by adopting an induction heating mode, because the metal iron is induced to heat up, a local high-temperature area appears, the iron is melted, and then the mutual adhesion grows up, the subsequent magnetic separation efficiency and the recovery rate are effectively improved, and the problems of small iron size and difficult magnetic separation under the low-temperature reduction condition are solved. In addition, because a hot charging and hot conveying mode is adopted, only metal iron is inductively heated in the induction heating mode, the energy consumption is low, and the high-efficiency magnetic separation recovery of the iron is realized while the cost is not remarkably increased; or directly entering an electric furnace for melting and separating to obtain the low-phosphorus molten iron.

Drawings

To more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required in the embodiments will be briefly described below, and it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope of the present application.

FIG. 1 is a schematic diagram of a high temperature reactor used in a weight loss experiment;

FIG. 2 is a graph of weight loss rate obtained from a weight loss experiment;

fig. 3 is a process flow diagram of the method for combining high-phosphorus iron ore and stone coal provided by the embodiment.

Detailed Description

The terms as used herein:

"by 8230; \ 8230; preparation" is synonymous with "comprising". The terms "comprises," "comprising," "includes," "including," "has," "having," "contains," "containing," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

The conjunction "consisting of 823070, 8230composition" excludes any unspecified elements, steps or components. If used in a claim, the phrase is intended to claim as closed, meaning that it does not contain materials other than those described, except for the conventional impurities associated therewith. When the phrase "consisting of 8230' \8230"; composition "appears in a clause of the subject matter of the claims and not immediately after the subject matter, it defines only the elements described in the clause; no other elements are excluded from the claims as a whole.

When an amount, concentration, or other value or parameter is expressed as a range, preferred range, or as a range of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted to include the ranges "1 to 4," "1 to 3," "1 to 2 and 4 to 5," "1 to 3 and 5," and the like. When a range of values is described herein, unless otherwise specified, the range is intended to include the endpoints thereof, and all integers and fractions within the range.

In the examples, the parts and percentages are by mass unless otherwise indicated.

"part by mass" means a basic unit of measure indicating a mass ratio of a plurality of components, and 1 part may represent an arbitrary unit mass, for example, 1g or 2.689 g. If we say that the part by mass of the component A is a part by mass and the part by mass of the component B is B part by mass, the ratio of the part by mass of the component A to the part by mass of the component B is a: b. alternatively, the mass of the A component is aK and the mass of the B component is bK (K is an arbitrary number, and represents a multiple factor). It is unmistakable that, unlike the parts by mass, the sum of the parts by mass of all the components is not limited to 100 parts.

"and/or" is used to indicate that one or both of the illustrated conditions may occur, e.g., a and/or B includes (a and B) and (a or B).

carrying out induction heating on the reduced pellets, cooling, crushing and carrying out magnetic separation to obtain low-phosphorus metallic iron particles; or carrying out electric furnace melting separation on the reduced pellets and connecting the reduced pellets into a short-flow steelmaking flow to obtain low-phosphorus molten iron;

The phosphorus in the high-phosphorus iron ore is mainly endowed with apatite phase Ca ₁₀ (PO ₄ ) ₆ F ₂ SiO in medium and stone coal ₂ The content of the phosphorus is high, so that if the high-phosphorus iron ore and the high-carbon stone coal are combined, not only can carbon resources in the stone coal be effectively utilized to provide a reducing agent, but also the temperature of the coupling reaction between the silicon dioxide and the apatite phase in the stone coal and carbon is lower, and the low-temperature removal of phosphorus can be realized.

Under the condition that only carbon is reduced, dephosphorization reaction of apatite occurs as follows:

Ca ₁₀ (PO ₄ ) ₆ F ₂ (s)+15C(s)=CaF ₂ (s)+15CO(g)+3P ₂ (g)+9CaO(s)

the Gibbs free energy of the reaction becomes

On the contraryThe temperature is 1443 ℃ or higher.

In the presence of SiO ₂ Under the conditions of (1), the dephosphorization reaction of apatite is as follows:

2Ca ₁₀ (PO ₄ ) ₆ F ₂ (s)+30C(s)+21SiO ₂ (s)=SiF ₂ (g)+30CO(g)+6P ₂ (g)+20CaSiO ₃ (s)

the Gibbs free energy of the reaction becomes

The reaction temperature is above 698 ℃.

As can be seen from the above reaction, the reaction temperature can be reduced remarkably in theory in the presence of silica. The method has the advantages that the reduction temperature does not need to reach 1200 ℃ like coal-based direct reduction, so that the iron obtained by reduction cannot become liquid, the phosphorus absorption of the iron is effectively reduced, the phosphorus absorption of the iron is reduced, and most of phosphorus is converted into gas to be volatilized and removed. However, in actual operation, the reduction temperature still needs to reach over 1100 ℃ for the above reaction to be carried out efficiently, and part of liquid iron is generated under the condition, which affects dephosphorization effect.

The main chemical components of the stone coal, as determined by XRF, are shown in table 1 below.

TABLE 1 main chemical composition of stone coal (wt%)

As can be seen from the above table, al is contained in the stone coal ₂ O ₃ The content of the iron ore is high, and when the stone coal and the high-phosphorus iron ore are used together, the iron ore can also be combined with Fe in the iron ore ₂ O ₃ And (4) coupling reaction. Therefore, when used in combination, the following coupling reaction occurs from the viewpoint of the composition of the reactants:

2Ca ₁₀ (PO ₄ ) ₆ F ₂ (s)+36C(s)+41SiO ₂ (s)+20Al ₂ O ₃ (s)+2Fe ₂ O ₃ (s)=SiF ₂ (g)+36CO(g)+6P ₂ (g)+20CaAl ₂ Si ₂ O ₈ (s)+4Fe(s)

the Gibbs free energy of the reaction becomes

The reaction temperature is over 609 ℃. Thus, it can be seen that Al ₂ O ₃ And Fe ₂ O ₃ The presence of (b) further lowers the reaction temperature. When the iron oxide is reduced by coal base, the iron oxide can be reduced to solid iron at the temperature of about 750 ℃, and the reaction temperature can be properly increased in order to ensure higher reaction speed. Therefore, the theory analysis can show that the stone coal and the high-phosphorus iron ore are combined, phosphorus removal and iron pre-reduction can be realized at 800-1000 ℃, and good conditions are provided for subsequent electric furnace melting.

In order to prove the rationality of thermodynamic analysis, a weight loss experimental study was conducted. The method is carried out by adopting a laboratory self-made high-temperature reaction furnace, and a schematic diagram is shown in figure 1. The high-temperature tubular resistance furnace is designed for a laboratory, and can realize high-precision control of atmosphere and temperature.

The stone coal sample and the high-phosphorus iron ore are mixed according to the mass ratio of 1. Different temperatures are set respectively, and after the sample is treated and uniformly mixed according to the method provided by the application (no pelletizing is performed in a verification experiment, no adhesive is added), the sample is placed into a furnace for experiment, and the experiment is performed for 20min at each temperature. Weight loss ratio

The calculation of (c) is as follows:

，

in the formula, m ₁ Is the initial weight of the sample, m ₂ Is the weight of the sample after reaction.

The final sample weight loss ratio is shown in fig. 2. As can be seen from fig. 2, the sample has reacted significantly at 800 c, with little increase in the weight loss rate of the sample above 1100 c. This result demonstrates that iron reduction and phosphorus removal can be accomplished already at 800-1100 deg.C. Finally, detection shows that the phosphorus content in the iron particles obtained by magnetic separation at 1000 ℃ is less than 0.02wt%, and the phosphorus content in the slag is less than 0.03wt%. The phosphorus in the sample has been proved to be effectively removed in the reduction stage by gasification.

And then, the iron reduced into small particles can further grow up through induction heating of the pre-reduction, and a foundation is laid for subsequent high-efficiency magnetic separation. The pellets can also be directly hot-charged and hot-fed for melting separation, calcium oxide is added in the melting separation process for slagging, the slag phase alkalinity can be further improved, rephosphorization is prevented, and finally the qualified low-phosphorus molten iron is obtained. Meanwhile, after magnetic separation or melt separation, vanadium enters tailings, so that efficient wet leaching can be realized, the effect of 1+1 & gt 2 is really realized, phosphorus in high-phosphorus iron ore is removed in one-step roasting process, iron oxide is pre-reduced by using carbon in stone coal, and vanadium in the stone coal is released from a crystal lattice structure of vanadium mica and is oxidized, so that vanadium can be extracted in the subsequent wet leaching process.

In an alternative embodiment, the high-phosphorus iron ore is pre-crushed to obtain particles with the particle size of 10 meshes or less, and the stone coal is pre-crushed to obtain particles with the particle size of 50 meshes or less.

The granularity of the high-phosphorus iron ore is preferably 10-50 meshes, and the granularity of the stone coal is preferably 80-120 meshes.

In an alternative embodiment, the mass ratio of the high-phosphorus iron ore, the stone coal and the binder is 100: (80-120): (1-5).

Optionally, the mass ratio of the high-phosphorus iron ore, the stone coal and the binder may be 100:80: 1. 100, and (2) a step of: 90: 3. 100, and (2) a step of: 100: 5. 100, and (2) a step of: 110: 2. 100:120:4 or 100: (80-120): (1-5).

In an alternative embodiment, the binder comprises bentonite and/or water glass, and has a particle size of 200 mesh or less.

The particle size of the binder is preferably 200-300 mesh.

In an optional embodiment, the temperature of the heating reduction reaction is 800-1100 ℃ and the time is 20-250min;

the metallization rate of the reduced pellet is greater than or equal to 90%.

Optionally, the temperature of the heating reduction reaction may be any value between 800 ℃, 900 ℃,1000 ℃, 1100 ℃ or 800-1100 ℃, and the time may be any value between 20min, 40min, 60min, 80min, 100min, 120min, 140min, 160min, 180min, 200min, 220min, 240min, 250min or 20-250 min.

In an alternative embodiment, the maximum temperature of the induction heating is 1200 ℃ for 10-20min.

Optionally, the time of the induction heating may be any value between 10min, 15min, 20min or 10-20min.

In an alternative embodiment, the material is pulverized to an average particle size of 100 mesh or less after the cooling.

In an alternative embodiment, the low-phosphorous metallic iron particles have a total iron content of 92 wt.% or greater and a phosphorous content of less than 0.1 wt.%.

In an alternative embodiment, the electric furnace melt separation temperature is 1450-1550 ℃;

The slag is the tailings formed by the remaining oxides after pre-reduction iron is removed in the flow.

Optionally, the temperature of the electric furnace melting separation can be any value between 1450 ℃, 1500 ℃, 1550 ℃ or 1450-1550 ℃; the proportion of the calcium oxide to the slag can be 1:0.4, 1:0.5, 1:0.6 or 1: (0.4-0.6).

In an alternative embodiment, the phosphorus content of the low-phosphorus molten iron is 0.1wt% or less.

Embodiments of the present application will be described in detail below with reference to specific examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present application and should not be construed as limiting the scope of the present application. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

Example 1

The composition of the stone coal is shown in table 1, and the main composition of the high-phosphorus iron ore is shown in table 2:

TABLE 2 high phosphorus iron ore main component (wt%)

As shown in fig. 2, the present embodiment provides a method for combining high-phosphorus iron ore and stone coal, comprising the following steps:

water glass is used as a binder, and the granularity is 200 meshes; the high-phosphorus iron ore is pre-crushed to obtain particles with the granularity of 10 meshes, and the stone coal is pre-crushed to obtain particles with the granularity of 100 meshes.

The mass ratio of the high-phosphorus iron ore, the stone coal and the binder is 100:90:1.5, uniformly mixing the materials, and then forming pellets of 25-55mm by a uniformly mixing machine and a ball press. And then drying to obtain the pellets with the water content of less than 1wt%.

And (3) reducing the pellets by adopting a sealed steel belt furnace, wherein the maximum reduction temperature is 1000 ℃, the reduction time is 30min, and obtaining the metallized pellets with the reduction rate of 92%. And (3) conveying the obtained pellet hot charge heat to an induction furnace for heating, controlling the temperature of the material to be 1200 ℃ at most, and carrying out induction heating for 20min. And then, grinding the pellets to 150 meshes, and carrying out magnetic separation to finally obtain iron particles with the total iron content of 96wt%, wherein the overall iron recovery rate reaches 89%, and the phosphorus content in the iron particles is 0.06wt%.

Example 2

The composition of the stone coal is shown in table 1, and the composition of the high-phosphorus iron ore is shown in table 3:

TABLE 3 composition of high-phosphorus iron ore (wt%)

Water glass is used as a binder, and the granularity is 150 meshes; the high-phosphorus iron ore is pre-crushed to obtain particles with the granularity of 30 meshes, and the stone coal is pre-crushed to obtain particles with the granularity of 120 meshes.

The mass ratio of the high-phosphorus iron ore, the stone coal and the binder is 100:120:2, uniformly mixing the materials, and then forming pellets of 20-60mm by using a uniformly mixing machine and a ball press. And then drying to obtain the pellets with the water content of less than 2 wt%.

And (3) reducing the pellets by adopting a sealed steel belt furnace, wherein the maximum reduction temperature is 850 ℃, the reduction time is 200min, and obtaining the metallized pellets with the reduction rate of 91%. And (3) conveying the obtained pellet hot charge heat to an induction furnace for heating, controlling the temperature of the material to be 1200 ℃ at most, and carrying out induction heating for 15min. And then, grinding the pellets to 150 meshes, and carrying out magnetic separation to obtain iron particles with the total iron content of 94wt%, wherein the overall iron recovery rate reaches 88% and the phosphorus content in the iron particles is 0.08wt%.

Example 3

The composition of the stone coal is shown in table 1, and the composition of the high-phosphorus iron ore is shown in table 4:

TABLE 4 composition of high-phosphorus iron ore (wt%)

Water glass is used as a binder, and the granularity is 180 meshes; the high-phosphorus iron ore is pre-crushed to obtain particles with the granularity of 50 meshes, and the stone coal is pre-crushed to obtain particles with the granularity of 120 meshes.

The mass ratio of the high-phosphorus iron ore, the stone coal and the binder is 100:100:2, uniformly mixing the materials, and then forming pellets with the diameter of 30-60mm by using a uniformly mixing machine and a ball press machine. Then drying is carried out, thus obtaining the pellet with the water content of less than 1.5 wt%.

And (3) carrying out pellet reduction by adopting a sealed steel belt furnace, wherein the maximum reduction temperature is 950 ℃, and the reduction time is 50min, so as to obtain the metallized pellets with the reduction rate of 93%. And (3) feeding the obtained pellet hot charge heat into an induction furnace for heating, controlling the maximum temperature of the material to be 1200 ℃, and carrying out induction heating for 20min. And then, grinding the pellets to 150 meshes, and carrying out magnetic separation to obtain iron particles with the total iron content of 94% finally, wherein the overall iron recovery rate reaches 94%, and the phosphorus content in the iron particles is 0.09wt%.

Example 4

The reduced pellets obtained in the previous example 3 were hot charged and hot-separated in an electric furnace, and calcium oxide in an amount of 50% of the amount of slag was added to conduct slagging, to prevent rephosphorization and to further remove phosphorus. The temperature of the metal pellets entering the electric furnace is 800 ℃, the temperature is raised to 1500 ℃, the metallized pellets are completely melted at this time, qualified molten iron containing 0.02wt% of phosphorus is finally obtained through smelting, and the overall yield of the iron is 89%.

Example 5

The reduced pellets obtained in the previous example 2 were hot charged and hot-separated in an electric furnace, and calcium oxide in an amount of 40% of the amount of slag was added to conduct slagging, to prevent rephosphorization and to further remove phosphorus. The temperature of the metal pellets in the electric furnace is 750 ℃, the temperature is raised to 1450 ℃, the metallized pellets are completely melted, qualified molten iron containing 0.05wt% of phosphorus is finally obtained through smelting, and the overall yield of iron is 87%.

Comparative example 1

The composition of the high-phosphorus iron ore is shown in table 3:

water glass is used as a binder, and the granularity is less than or equal to 200 meshes; the high-phosphorus iron ore is pre-crushed to obtain particles with the particle size of 40 mu, and the coal coke is pre-crushed to obtain particles with the particle size of 150 mu.

The mass ratio of the high-phosphorus iron ore, the coal coke and the binder is 100:50: and 5, uniformly mixing the materials, and then forming pellets with the diameter of 20-60mm by using a uniformly mixing machine and a ball press machine. And then drying to obtain the pellets with the water content of less than 2 wt%.

And (3) carrying out pellet reduction by adopting a sealed steel belt furnace, wherein the minimum reduction temperature is 1250 ℃ and the reduction time is 20min in order to meet the reduction removal of phosphorus, and finally obtaining the metallized pellets with the reduction rate of 88%. The overall iron recovery rate reaches 84 percent. Reduced iron is obtained after magnetic separation, but the phosphorus content in iron particles is 0.5wt%, and the phosphorus content is too high, so that the use of a subsequent process is difficult to meet, molten iron dephosphorization is required, and the smelting cost is increased.

The method for combining the high-phosphorus iron ore and the stone coal has the following advantages:

1. the synergistic utilization of two refractory mineral resources fully utilizes the resource characteristics of the two minerals and the low-temperature dephosphorization effect of the stone coal on the high-phosphorus iron ore, the stone coal contains a large amount of reducing agent carbon and also contains a large amount of compounds such as silicon dioxide, aluminum oxide and the like, the reduction temperature of phosphorus can be effectively reduced, and the reduction, gasification and removal of phosphorus are realized within the temperature range without generating molten iron. This is the core innovation idea.

2. Compared with the traditional direct reduction process in which coal tar is directly added, the method adopts the refractory solid waste stone coal, reduces the consumption of high-quality coal tar, realizes dephosphorization and reduced iron by adopting carbon resources which are difficult to utilize in the stone coal, and realizes the maximum utilization of the stone coal. Meanwhile, the generated flue gas mainly contains CO, and can be used as fuel for preheating or drying pellets, so that the energy consumption of the whole process is reduced, and clean production is realized.

3. In the process of reduction dephosphorization, the spinel crystal lattice of vanadium in the stone coal can be destroyed, and raw materials are provided for subsequent wet leaching. Two kinds of minerals are processed through one flow, so that the energy consumption is effectively saved, and the effect of maximizing resource utilization is realized.

4. The whole process is simple, the existing production process of the metallized pellet can be referred, the raw materials are all mineral resources with large assigned amount in China, the practicability is strong, and the large-scale production is easy to realize.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and these modifications or substitutions do not depart from the scope of the technical solutions of the embodiments of the present application.

Moreover, those skilled in the art will appreciate that while some embodiments herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the application and form different embodiments. For example, in the claims above, any of the claimed embodiments may be used in any combination. The information disclosed in this background section is only for enhancement of understanding of the general background of the application and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Claims

1. A method for combining high-phosphorus iron ore and stone coal is characterized by comprising the following steps:

2. The method for combining high-phosphorus iron ore and stone coal according to claim 1, characterized in that the high-phosphorus iron ore is pre-crushed to obtain particles with a particle size of 10 meshes or less, and the stone coal is pre-crushed to obtain particles with a particle size of 50 meshes or less.

3. The method for combining the high-phosphorus iron ore and the stone coal as claimed in claim 1, wherein the mass ratio of the high-phosphorus iron ore to the stone coal to the binder is 100: (80-120): (1-5).

4. The method for combining high-phosphorus iron ore and stone coal according to claim 1, wherein the binder comprises bentonite and/or water glass, and the particle size is 200 meshes or less.

5. The method for combining the high-phosphorus iron ore and the stone coal as claimed in claim 1, wherein the temperature of the heating reduction reaction is 800-1100 ℃ and the time is 20-250min;

the metallization rate of the reduced pellet is greater than or equal to 90%.

6. The method for combining high-phosphorus iron ore and stone coal according to claim 1, wherein the maximum temperature of the induction heating is 1200 ℃ and the time is 10-20min.

7. The process of claim 1, wherein the material is crushed to an average particle size of 100 mesh or less after the cooling.

8. The process of claim 1, wherein the low-phosphorous iron metal particles have a total iron content of 92 wt.% or more and a phosphorous content of less than 0.1 wt.%.

9. The method for combining the high-phosphorus iron ore and the stone coal as claimed in claim 1, wherein the melting temperature of the electric furnace is 1450-1550 ℃;

10. The process for combined use of high phosphorus iron ore and stone coal according to any one of claims 1 to 9, characterized in that the phosphorus content in the low phosphorus iron ore is equal to or less than 0.1wt%.