阅读说明：本技术 一种基于矿相分段精准调控的复杂铁矿石强化分选方法 (Complex iron ore reinforced separation method based on mineral phase subsection accurate regulation and control ) 是由 高鹏 袁帅 张琦 韩跃新 李艳军 孙永升 于 2020-06-03 设计创作，主要内容包括：一种基于矿相分段精准调控的复杂铁矿石强化分选方法,按以下步骤进行：(1)将复杂铁矿石破碎后磨细；(2)将矿粉输送到预氧化焙烧炉内,在悬浮状态进行预氧化焙烧,再进入旋风分离器；(3)预氧化焙烧料经过旋风分离后,排放到蓄热还原焙烧炉,在悬浮状态进行还原焙烧；(4)还原物料进入一级冷却旋风分离器,氮气冷却至200～300℃；(5)冷却还原物料经流动密封阀进入二级冷却旋风分离器,与空气发生再氧化反应,温度降至≤100℃；(6)进行弱磁选获得铁精矿。本发明的方法流程简单,单位处理量的能耗及成本低,产品性质易控制,易实现设备大型化。(A complex iron ore reinforced separation method based on mineral phase subsection accurate regulation is carried out according to the following steps: (1) crushing and grinding the complex iron ore; (2) conveying the mineral powder into a pre-oxidation roasting furnace, carrying out pre-oxidation roasting in a suspension state, and then entering a cyclone separator; (3) the pre-oxidized roasting material is discharged to a heat storage reduction roasting furnace after cyclone separation, and is subjected to reduction roasting in a suspension state; (4) the reducing material enters a primary cooling cyclone separator, and nitrogen is cooled to 200-300 ℃; (5) the cooled and reduced material enters a secondary cooling cyclone separator through a flow seal valve and undergoes reoxidation reaction with air, and the temperature is reduced to be less than or equal to 100 ℃; (6) carrying out low intensity magnetic separation to obtain iron ore concentrate. The method has the advantages of simple flow, low energy consumption and cost of unit treatment capacity, easily controllable product properties and easy realization of large-scale equipment.)

1. A complex iron ore reinforced separation method based on mineral phase subsection accurate regulation is characterized by comprising the following steps:

(1) crushing the complex iron ore by a crusher until the particle size is 2-15 mm, and then grinding the complex iron ore by an ore grinding machine until the part with the particle size of-0.074 mm accounts for 50-90% of the total mass to obtain ore powder; the iron grade TFe of the complex iron ore is 25-45%, and the complex iron ore contains SiO according to mass percentage₂25～55％；

(2) The method comprises the steps of adopting a pre-oxidation roasting furnace with a burner and an air inlet at the bottom, arranging a feed inlet at the lower part of the pre-oxidation roasting furnace, communicating the upper part with a cyclone separator through a material channel, communicating an exhaust port of the cyclone separator with an induced draft fan through a pipeline, introducing combustion flue gas generated by combustion of natural gas introduced into the burner into the pre-oxidation roasting furnace, introducing air into the pre-oxidation roasting furnace under the condition of starting the induced draft fan, conveying mineral powder into the pre-oxidation roasting furnace from the lower part of the pre-oxidation roasting furnace, keeping the mineral powder in a suspension state in the pre-oxidation suspension roasting furnace under the action of negative pressure and air flow, heating the mineral powder to 650-700 ℃ for pre-oxidation roasting, removing adsorbed water, crystal water and other volatile components in the mineral powder, and converting the mineral phases of different iron ores₂O₃(ii) a The pre-oxidized product obtained after the pre-oxidation roasting is a pre-oxidation roasting material and enters a cyclone separator under the action of airflow;

(3) under the condition of introducing nitrogen and reducing gas into the regenerative reduction roasting furnace, the preoxidized roasting material is subjected to cyclone separation in the cyclone separator, is discharged into the regenerative reduction roasting furnace, is in a suspension state under the action of negative pressure and air flow, and is subjected to reduction roasting with the reducing gas at the temperature of 500-600 ℃, α -Fe₂O₃Is reduced to produce Fe₃O₄(ii) a Reducing products obtained after the reduction roasting are reducing materials and are discharged from a side discharge hole of the heat storage reduction roasting furnace;

(4) conveying the reducing material discharged from the heat storage reduction roasting furnace to a primary cooling cyclone separator; introducing nitrogen from a feed inlet of the primary cooling cyclone separator, and discharging the nitrogen from an air outlet of the primary cooling cyclone separator; carrying out cyclone separation on the reduced material under the condition of nitrogen atmosphere, cooling to 200-300 ℃ to obtain a cooled reduced material, and discharging from a discharge hole of a primary cooling cyclone separator;

(5) the cooled reducing material discharged from the primary cooling cyclone separator enters a flow seal valve, and enters a secondary cooling cyclone separator after being discharged from the flow seal valve; at the moment, air is introduced from a feed inlet of the secondary cooling cyclone separator, and the air is discharged from an air outlet of the secondary cooling cyclone separator; the cooled and reduced material is separated in cyclone in air atmosphere and is reoxidized to produce Fe₃O₄Oxidized to generate ferromagnetic mineral gamma-Fe₂O₃Reducing the temperature of the obtained roasted product to be less than or equal to 100 ℃, and discharging the formed reoxidized material from a discharge hole of the secondary cooling cyclone separator;

(6) and carrying out low-intensity magnetic separation on the reoxidation material, wherein the magnetic field intensity is 1000-2000 Oe, and the obtained magnetic product is iron ore concentrate.

2. The method for intensively separating the complex iron ores based on the precise control of the mineral phase segmentation as claimed in claim 1, wherein in the step (2), the retention time of the solid materials in the pre-oxidation roasting furnace is 2-10 min.

3. The method for the enhanced separation of the complex iron ores based on the accurate control of the ore phase segmentation according to claim 1, wherein in the step (3), the reducing gas is CO or H₂Or coal gas; the amount of reducing gas is determined according to the CO/H required by the complete reaction of reduction roasting₂1: 1-1.3 times of theoretical amount, and the reaction formula for complete reaction is as follows:

Fe₂O₃+H₂/CO→Fe₃O₄+H₂O/CO₂。

4. the method for intensively sorting the complex iron ores based on the precise control of the ore phase segmentation according to claim 1, wherein in the step (3), the volume flow ratio of nitrogen to reducing gas in the regenerative reduction roasting furnace is (1-5): 1.

5. The method for intensively sorting the complex iron ores based on the precise control of the mineral phase segmentation as claimed in claim 1, wherein in the step (3), the retention time of the solid materials in the regenerative reduction roasting furnace is 10-30 min.

6. The method for intensively sorting the complex iron ores based on the precise control of the mineral phase segmentation as claimed in claim 1, wherein in the step (4), the retention time of the reduced materials in the primary cooling cyclone separator is 2-5 min.

7. The method for intensively sorting the complex iron ores based on the precise control of the mineral phase segmentation as claimed in claim 1, wherein in the step (5), the retention time of the cooled and reduced materials in the secondary cooling cyclone separator is 1-3 min.

8. The method for the enhanced separation of the complex iron ores based on the accurate control of the ore phase segmentation according to claim 1, characterized in that the iron grade TFe of the iron ore concentrate is not less than 60%.

9. The complex iron ore reinforced separation method based on mineral phase subsection precise control as claimed in claim 1, characterized in that the recovery rate of Fe is more than or equal to 90%.

Technical Field

The invention belongs to the technical field of mineral processing, and particularly relates to a complex iron ore reinforced separation method based on mineral phase segmentation accurate regulation.

Background

At present, a large amount of low-grade complex refractory iron ore resources are not effectively utilized on a large scale, the iron grade of the ore is low, the iron mineral has fine embedded particle size, the phase of the iron mineral is complex (mainly hematite, goethite, limonite, siderite, magnetite and the like), the complex refractory iron ore resources are effectively utilized, and the method has important significance for relieving the situation of insufficient iron ore resource supply.

Patent CN104593588 discloses a method for roasting lean iron ore in a rotary kiln, which proposes that iron ore with iron content of about 40% is used as a raw material, and the iron contained in the iron ore is roasted and recovered by the rotary kiln, so that the method can realize the utilization of iron resources to a certain extent, and reduce the use amount of coal; however, the conventional rotary kiln calcining equipment is adopted, the processing capacity is low, the product quality is poor, a coal injection device needs to be assembled, and the process flow is complex.

Patent CN 107630139 discloses a fluidized suspension preheating prereduction device and method for iron ore, which can recover a large amount of heat in waste gas in the smelting link, save preheating heat and reduce energy loss; the method can reduce energy consumption to a certain extent, but the iron phase in the complex iron ore is complex, the reduction speed of iron minerals is different, the oxidation atmosphere and the reduction atmosphere coexist, the quality of a roasted product is influenced, and the production efficiency is reduced; the same problem exists with the solution disclosed in patent CN 105316476.

Patent CN 107930843 discloses a re-roasting method for a dry type pre-separation tailing return furnace for suspension roasting of refractory iron ores, and proposes that the refractory iron ores are subjected to suspension roasting, and are re-selected after dry type pre-separation tailing discarding; taking dry type pre-concentration operation tailings of refractory iron ores as an ore source, carrying out fluidized reduction roasting, and carrying out pre-concentration and pre-concentration operation through a magnetic separator; the products of the two-time concentration operation enter a grinding system to obtain final iron ore concentrate; the method can recover iron minerals in complex ores to a certain extent, but the product needs to be roasted twice, and the method has the defects of high energy consumption, complex process flow, difficult separation of iron minerals and gangue in the reduced product, low concentrate grade and the like.

Disclosure of Invention

Aiming at the problems of the existing complex refractory iron ore in the treatment technology, the invention provides a complex iron ore reinforced separation method based on mineral phase subsection accurate regulation.

The method of the invention is carried out according to the following steps:

1. crushing the complex iron ore by a crusher until the particle size is 2-15 mm, and then grinding the complex iron ore by an ore grinding machine until the part with the particle size of-0.074 mm accounts for 50-90% of the total mass to obtain ore powder; the iron grade TFe of the complex iron ore is 25-45%, and the complex iron ore contains SiO according to mass percentage₂25～55％；

2. The method comprises the steps of adopting a pre-oxidation roasting furnace with a burner and an air inlet at the bottom, arranging a feed inlet at the lower part of the pre-oxidation roasting furnace, communicating the upper part with a cyclone separator through a material channel, communicating an exhaust port of the cyclone separator with an induced draft fan through a pipeline, introducing combustion flue gas generated by combustion of natural gas introduced into the burner into the pre-oxidation roasting furnace, introducing air into the pre-oxidation roasting furnace under the condition of starting the induced draft fan, conveying mineral powder into the pre-oxidation roasting furnace from the lower part of the pre-oxidation roasting furnace, keeping the mineral powder in a suspension state in the pre-oxidation suspension roasting furnace under the action of negative pressure and air flow, heating the mineral powder to 650-700 ℃ for pre-oxidation roasting, removing adsorbed water, crystal water and other volatile components in the mineral powder, and converting the mineral phases of different iron ores₂O₃(ii) a The pre-oxidized product obtained after the pre-oxidation roasting is a pre-oxidation roasting material and enters a cyclone separator under the action of airflow;

3. the discharge hole of the cyclone separator is communicated with the feed inlet of the heat storage reduction roasting furnace, the bottom of the heat storage reduction roasting furnace is provided with a nitrogen inlet and a reducing gas inlet, and the side part of the heat storage reduction roasting furnace is provided with a discharge hole; under the condition of introducing nitrogen and reducing gas into the heat-accumulating reduction roasting furnace, the preoxidized roasted material is separated by cyclone in a cyclone separatorDischarging the powder into a regenerative reduction roasting furnace, keeping the powder in a suspension state under the action of negative pressure and airflow, and carrying out reduction roasting on the powder and a reducing gas at the temperature of 500-600 ℃, wherein α -Fe₂O₃Is reduced to produce Fe₃O₄(ii) a Reducing products obtained after the reduction roasting are reducing materials and are discharged from a side discharge hole of the heat storage reduction roasting furnace;

4. conveying the reducing material discharged from the heat storage reduction roasting furnace to a primary cooling cyclone separator; introducing nitrogen from a feed inlet of the primary cooling cyclone separator, and discharging the nitrogen from an air outlet of the primary cooling cyclone separator; carrying out cyclone separation on the reduced material under the condition of nitrogen atmosphere, cooling to 200-300 ℃ to obtain a cooled reduced material, and discharging from a discharge hole of a primary cooling cyclone separator;

5. the cooled reducing material discharged from the primary cooling cyclone separator enters a flow seal valve, and enters a secondary cooling cyclone separator after being discharged from the flow seal valve; at the moment, air is introduced from a feed inlet of the secondary cooling cyclone separator, and the air is discharged from an air outlet of the secondary cooling cyclone separator; the cooled and reduced material is separated in cyclone in air atmosphere and is reoxidized to produce Fe₃O₄Oxidized to generate ferromagnetic mineral gamma-Fe₂O₃Reducing the temperature of the obtained roasted product to be less than or equal to 100 ℃, and discharging the formed reoxidized material from a discharge hole of the secondary cooling cyclone separator;

6. and carrying out low-intensity magnetic separation on the reoxidation material, wherein the magnetic field intensity is 1000-2000 Oe, and the obtained magnetic product is iron ore concentrate.

The main phases of the complex iron ore are goethite, hematite, limonite, siderite or pyrite, and the particle size is less than 200 mm.

The crusher is a jaw crusher or a disc crusher.

The ore mill is a high-pressure roller mill or a ball mill.

In the step 2, the main reaction formula of the pre-oxidation roasting is as follows:

Fe₂O₃·nH₂O→Fe₂O₃+H₂O、

FeCO₃+O₂→Fe₂O₃+CO₂and

Fe₃O₄+O₂→Fe₂O₃+CO₂。

in the step 2, the retention time of the solid materials in the pre-oxidation roasting furnace is 2-10 min.

In the step 3, the reducing gas is CO or H₂Or coal gas; the amount of reducing gas is determined according to the CO/H required by the complete reaction of reduction roasting₂1: 1-1.3 times of theoretical amount, and the reaction formula for complete reaction is as follows:

Fe₂O₃+H₂/CO→Fe₃O₄+H₂O/CO₂。

in the step 3, the volume flow ratio of the nitrogen to the reducing gas in the regenerative reduction roasting furnace is (1-5): 1.

In the step 3, the retention time of the solid materials in the heat-storage reduction roasting furnace is 10-30 min.

In the step 4, the retention time of the reduced materials in the primary cooling cyclone separator is 2-5 min.

In the step 5, the retention time of the cooling and reducing material in the secondary cooling cyclone separator is 1-3 min.

In the step 5, the main reaction formula of the reoxidation reaction is as follows:

Fe₃O₄+O₂→γ-Fe₂O₃。

the iron grade TFe of the iron ore concentrate is not less than 60 percent.

In the method, the recovery rate of Fe is more than or equal to 90 percent.

In the step 4, the tubular heat exchanger is arranged in the primary cooling cyclone separator, and the sensible heat of the reduced material is recovered by the tubular heat exchanger.

In the step 5, the tubular heat exchanger is arranged in the secondary cooling cyclone separator, and sensible heat of the cooled and reduced material and latent heat released by reoxidation reaction are recovered by the tubular heat exchanger.

In the step 6, the low-intensity magnetic separation adopts a wet low-intensity magnetic separator or a dry magnetic separator.

The principle of the invention is as follows: the mineral powder is dehydrated and adsorbed in an oxidizing atmosphere at 650-700 ℃ in a pre-oxidation roasting furnace to form water of crystallization and other volatile matters, and various types of iron minerals such as goethite, limonite, siderite and magnetite in the ore are converted into Fe with uniform components₂O₃(ii) a Products of pre-oxidation operations, iron being predominantly present in Fe₂O₃Performing the following steps; in the case of reduction roasting, Fe₂O₃Is reduced to produce Fe₃O₄(ii) a The reduced material is cooled in two stages, wherein the temperature of the first stage is cooled to 200-300 ℃ by nitrogen, and the iron phase does not change in the first stage; in the second stage, air oxidation is carried out on the material with the temperature of 200-300 ℃ to ensure that Fe₃O₄Produce ferromagnetic mineral gamma-Fe with low coercive force₂O₃The phenomenon that magnetic agglomeration and gangue are carried into the concentrate can be reduced without demagnetizing equipment, and the product quality is improved; meanwhile, the reaction is exothermic, and the transformation of an iron phase releases latent heat; the recovered latent heat and sensible heat can be used for power generation; magnetic iron minerals separated by magnetic separation are mainly artificial magnetite and gamma-Fe₂O₃Meanwhile, the grade and the recovery rate of iron are ensured, and the iron concentrate meets the requirements of iron-making operation.

The invention has the characteristics and advantages that: compared with the conventional magnetic separation and flotation process, the method can efficiently recover iron from the iron ore containing the composite iron mineral, and the iron mineral can be goethite, hematite, limonite, siderite, pyrite and the like, so that the efficient separation of iron and gangue can be realized; the gas-based roasting of the iron ore is adopted, so that the material is fluidized in the system, and compared with the traditional roasting means, the method has higher heat and mass transfer efficiency and can realize the high-efficiency reduction of iron minerals impregnated with fine particles in the complex iron ore; particularly, a roasting method of 'subsection precise regulation' is adopted, the 'oxidation-reduction-reoxidation' process of the complex iron ore is treated in sections, products with uniform properties are obtained in each stage, and therefore precise regulation and control of iron minerals in roasting are achievedMagnetite generated from siderite or pyrite after pre-oxidation reaction and reduction reaction) into gamma-Fe₂O₃Then, the magnetic agglomeration phenomenon of iron minerals is obviously reduced, the entrainment amount of gangue in the concentrate is obviously reduced, and the quality of the product is obviously improved; simple process flow, stable operation of equipment and a system, large treatment capacity, low energy consumption and cost of unit treatment capacity, easy control of product properties and easy realization of large-scale equipment.

Drawings

FIG. 1 is a schematic flow chart of a complex iron ore reinforced separation method based on accurate regulation and control of mineral phases in an embodiment of the invention;

FIG. 2 is a schematic diagram of a pre-oxidation baking process in an embodiment of the present invention;

FIG. 3 is a schematic view of a reduction roasting process in the example of the invention;

FIG. 4 is a schematic view of a cooling-reoxidation flow scheme in an example of the present invention;

fig. 5 is a schematic view of the structure of the flow seal valve in the embodiment of the present invention.

Detailed Description

The iron grade TFe of the complex iron ore adopted in the embodiment of the invention is 25-45%, and the complex iron ore contains SiO according to the mass percentage₂25-55%; the main phase is goethite, hematite, limonite, siderite or pyrite, and the particle size is below 200 mm.

The crusher used in the embodiment of the present invention is a jaw crusher or a disc crusher.

The ore mill adopted in the embodiment of the invention is a high-pressure roller mill or a ball mill.

In the embodiment of the invention, a wet low-intensity magnetic separator or a dry magnetic separator is adopted for low-intensity magnetic separation.

The reducing gas in the embodiment of the invention is CO and H₂Or coal gas.

The structural principle of the flow seal valve adopted in the embodiment of the invention is shown in fig. 5, a baffle plate is arranged in the flow seal valve to divide the interior of the flow seal valve into a feeding chamber and a discharging chamber, the top edge and the side edge of the baffle plate are fixedly connected with the interior of the flow seal valve, and a gap is formed between the bottom edge of the baffle plate and the bottom of the flow seal valve to serve as a horizontal channel; a feeding hole is formed in the side wall of the feeding chamber, a discharging hole is formed in the side wall of the discharging chamber, the feeding hole and the discharging hole are both positioned above the bottom edge of the baffle, and the feeding hole is higher than the discharging hole; the top of the discharging chamber is also provided with an air outlet pipe; the bottom plate of the feeding chamber is provided with a loosening air inlet communicated with the air inlet pipeline 1, and the bottom plate of the discharging chamber is provided with a fluidizing air inlet communicated with the air inlet pipeline 2; the air inlet pipeline 1 and the air inlet pipeline 2 are respectively communicated with an air source.

The working method of the flow seal valve in the embodiment of the invention comprises the following steps: solid materials entering from the feeding hole are gradually accumulated, when the horizontal channel is closed by the solid materials, gas is introduced into the feeding chamber through the gas inlet pipeline 1 to serve as loosening wind, and gas is introduced into the discharging chamber through the gas inlet pipeline 2 to serve as fluidized wind, so that the solid materials in the feeding chamber move towards the discharging chamber under the action of gas flow; along with the solid materials are gradually accumulated in the feeding chamber and the discharging chamber, when the top surface of the solid materials in the discharging chamber is lifted to the position of the discharging port, the solid materials in the discharging chamber are discharged from the discharging port under the action of air flow.

In the embodiment of the invention, an air pipeline 1 and an air inlet pipeline 2 of the flow seal valve are respectively communicated with a nitrogen source, and nitrogen is used as loosening air and fluidizing air; and the nitrogen discharged from the gas outlet pipe at the top of the flow seal valve enters a feed inlet of the primary cooling cyclone separator to form a nitrogen atmosphere.

In the embodiment of the invention, the feed inlet of the secondary cooling cyclone separator is communicated with the air compressor through a pipeline, and air is blown in through the air compressor to form air atmosphere.

In the embodiment of the invention, the tubular heat exchanger is arranged in the primary cooling cyclone separator, and the sensible heat of the reduced material is recovered by the tubular heat exchanger.

In the embodiment of the invention, the tubular heat exchanger is arranged in the secondary cooling cyclone separator, and sensible heat of the cooled and reduced material and latent heat released by reoxidation reaction are recovered by the tubular heat exchanger.

In the embodiment of the invention, the air discharged from the air outlet of the secondary cooling cyclone separator is transmitted to the air inlet at the bottom of the pre-oxidation roasting furnace to be used as combustion-supporting gas.