1. A treatment method of high-phosphorus oolitic iron ore comprises the following steps:

A) mixing the high-phosphorus oolitic iron ore, a dephosphorizing agent and water, and pressing into balls to obtain mixed balls;

the dephosphorization agent comprises calcium carbonate and calcium fluoride, wherein the mass ratio of the calcium carbonate to the calcium fluoride is 1: (0.15 to 0.30);

B) drying the mixed pellets and then carrying out oxidation roasting to obtain oxidation-roasted pellets;

C) carrying out reduction roasting on the oxidized and roasted pellets in a reducing atmosphere to obtain reduced pellets;

D) and (3) cooling the reduced pellets to room temperature in an air-isolated mode, and then carrying out ore grinding-magnetic separation to obtain a reduced iron product.

2. The treatment method according to claim 1, wherein the high-phosphorus oolitic iron ore is one or more of high-phosphorus oolitic hematite, high-phosphorus oolitic magnetite and high-phosphorus oolitic hematite/magnetite.

3. The treatment method according to claim 1, wherein the high-phosphorus oolitic iron ore has a particle size of less than 1mm, an iron grade of 43-60% and a phosphorus mass fraction of less than 1.5%.

4. The treatment method according to claim 1, wherein the mass ratio of the high-phosphorus oolitic iron ore to the dephosphorizing agent to the water is 1: (0.2-0.4): (0.05-0.15).

5. The treatment method according to claim 1, wherein the temperature of the oxidizing roasting is 1000 to 1500 ℃; the time of oxidizing roasting is 50-100 min.

6. The process according to claim 1, characterized in that said reducing atmosphere is natural gas pyrolysis gas and/or water gas.

7. The treatment method according to claim 1, wherein the temperature of the reduction roasting is 1100-1300 ℃; the time of the reduction roasting is 150-200 min.

8. The treatment method as claimed in claim 1, wherein the reduced pellets are cooled to room temperature in an air-isolated manner, crushed to-2 mm, and then subjected to two-stage ore grinding-magnetic separation to obtain a reduced iron product.

9. The treatment method according to claim 8, wherein in the two-stage ore grinding-magnetic separation, the content of particles in the ore ground to-0.074 mm in the first stage is not less than 65%, and the magnetic field intensity in the first stage is 1600-1800 oersted; the content of particles of which the diameter is-0.074 mm in the second-stage ore grinding is not less than 85 percent, and the magnetic field intensity of the second-stage magnetic separation is 1300-1400 oersted.

Background

With the rapid development of the iron and steel industry in the world, the high-grade iron ore resources are gradually reduced, and the development of the intractable iron ore with rich reserves is of great significance. High-phosphorus iron ore is one of the typical representatives of the refractory iron ores. High-phosphorus iron ore is mainly distributed in the united states, france, uk, canada, alkinia, nigeria, kazakhstan and china, with a total reserve of over 2 x 1010 t. Because the structure of the ore is complex and the phosphorus content is high, only iron ore concentrate with higher phosphorus content can be obtained by adopting a physical ore dressing process, if the product is used as a raw material for blast furnace ironmaking, almost all phosphorus can be enriched into molten iron in the smelting process, and the high-phosphorus molten iron can not meet the requirement of steelmaking on the phosphorus content of the raw material, so that dephosphorization before the steelmaking process is a reasonable way for realizing the effective utilization of the high-phosphorus iron ore.

At present, the utilization of high-phosphorus iron ore is researched more, and the research on the related processes for improving iron and reducing phosphorus is also quite deep, but the current research mostly adopts methods such as flotation, flotation-magnetic separation combination, chemical leaching, biological leaching and the like, and the methods are simple to operate, but the grade, the recovery rate and the like of the obtained iron ore concentrate are low, and the phosphorus removal effect is poor, so that the research on a method for treating the high-phosphorus iron ore, which is efficient, convenient, environment-friendly and industrially applicable, is extremely important.

Disclosure of Invention

The invention aims to provide a treatment method of high-phosphorus oolitic iron ore, the method has high phosphorus removal rate, the iron grade and recovery rate of the obtained powder reduced iron are high, and the reduction effect is not influenced by the change of the iron grade and phosphorus content of the raw ore within a certain range.

The invention provides a method for treating high-phosphorus oolitic iron ore, which comprises the following steps:

A) mixing the high-phosphorus oolitic iron ore, a dephosphorizing agent and water, and pressing into balls to obtain mixed balls;

the dephosphorization agent comprises calcium carbonate and calcium fluoride, wherein the mass ratio of the calcium carbonate to the calcium fluoride is 1: (0.15 to 0.30);

B) drying the mixed pellets and then carrying out oxidation roasting to obtain oxidation-roasted pellets;

C) carrying out reduction roasting on the oxidized and roasted pellets in a reducing atmosphere to obtain reduced pellets;

D) and (3) cooling the reduced pellets to room temperature in an air-isolated mode, and then carrying out ore grinding-magnetic separation to obtain a reduced iron product.

Preferably, the high-phosphorus oolitic iron ore is one or more of high-phosphorus oolitic hematite, high-phosphorus oolitic magnetite and high-phosphorus oolitic hematite/magnetite.

Preferably, the particle size of the high-phosphorus oolitic iron ore is less than 1mm, the iron grade is 43-60%, and the mass fraction of phosphorus is less than 1.5%.

Preferably, the mass ratio of the high-phosphorus oolitic iron ore to the dephosphorizing agent to the water is 1: (0.2-0.4): (0.05-0.15).

Preferably, the temperature of the oxidizing roasting is 1000-1500 ℃; the time of oxidizing roasting is 50-100 min.

Preferably, the reducing atmosphere is natural gas pyrolysis gas and/or water gas.

Preferably, the temperature of the reduction roasting is 1100-1300 ℃; the time of the reduction roasting is 150-200 min.

Preferably, the reduced pellets are isolated from air and cooled to room temperature, crushed to-2 mm, and then subjected to two-stage ore grinding-magnetic separation to obtain a reduced iron product.

Preferably, in the two-stage ore grinding-magnetic separation, the content of particles of which the diameter is minus 0.074mm in the first-stage ore grinding is not less than 65%, and the magnetic field intensity of the first-stage magnetic separation is 1600-1800 oersted; the content of particles of which the diameter is-0.074 mm in the second-stage ore grinding is not less than 85 percent, and the magnetic field intensity of the second-stage magnetic separation is 1300-1400 oersted.

The invention provides a method for treating high-phosphorus oolitic iron ore, which comprises the following steps: A) mixing the high-phosphorus oolitic iron ore, a dephosphorizing agent and water, and pressing into balls to obtain mixed balls; the dephosphorization agent comprises calcium carbonate and calcium fluoride, wherein the mass ratio of the calcium carbonate to the calcium fluoride is 1: (0.15 to 0.30); B) drying the mixed pellets and then carrying out oxidation roasting to obtain oxidation-roasted pellets; C) carrying out reduction roasting on the oxidized and roasted pellets in a reducing atmosphere to obtain reduced pellets; D) and (3) cooling the reduced pellets to room temperature in an air-isolated mode, and then carrying out ore grinding-magnetic separation to obtain a reduced iron product. The pellet is added with the dephosphorizing agent, the dephosphorizing agent reacts with components in the ore under the oxidizing atmosphere to change the mineral components of the pellet, and meanwhile, phosphorus originally existing in the iron mineral is generated into a single phosphorus-containing mineral, the structure of the ore can be changed, and conditions are created for reduction and dephosphorization of iron. The method has the advantages of simple process flow, high removal rate of phosphorus in the high-phosphorus oolitic iron ore, high iron grade and recovery rate of the obtained powder reduced iron, and no influence on the reduction effect due to the change of the iron grade and phosphorus content of the raw ore in a certain range.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

Fig. 1 is a flow chart of the treatment method of the high phosphorus oolitic iron ore.

Detailed Description

The invention provides a method for treating high-phosphorus oolitic iron ore, which comprises the following steps:

A) mixing the high-phosphorus oolitic iron ore, a dephosphorizing agent and water, and pressing into balls to obtain mixed balls;

the dephosphorization agent comprises calcium carbonate and calcium fluoride, wherein the mass ratio of the calcium carbonate to the calcium fluoride is 1: (0.15 to 0.30);

B) drying the mixed pellets and then carrying out oxidation roasting to obtain oxidation-roasted pellets;

C) carrying out reduction roasting on the oxidized and roasted pellets in a reducing atmosphere to obtain reduced pellets;

D) and (3) cooling the reduced pellets to room temperature in an air-isolated mode, and then carrying out ore grinding-magnetic separation to obtain a reduced iron product.

The method comprises the steps of firstly mixing raw materials and pressing the raw materials into balls, wherein the raw materials comprise raw ores, a dephosphorizing agent and water, and the mixed balls are obtained by pressing the mixed raw materials into the balls.

In the invention, the raw ore is preferably high-phosphorus oolitic hematite, high-phosphorus oolitic magnetite, high-phosphorus oolitic hematite/magnetite and the like, wherein the high-phosphorus oolitic hematite/magnetite refers to ore containing both the high-phosphorus oolitic hematite and the high-phosphorus oolitic magnetite; the particle size of the high-phosphorus oolitic iron ore is less than 1mm, the grade of iron in the raw ore is preferably 43-60%, and the phosphorus content is less than 1.5%.

The dephosphorizing agent is preferably a mixture of calcium carbonate and calcium fluoride, wherein the mass ratio of the calcium carbonate to the calcium fluoride is preferably 1: (0.15-0.30), specifically, in the embodiment of the invention, it can be 1:0.15 or 1: 0.30.

In the present invention, the mass ratio of the raw ore, the dephosphorizing agent and the water is preferably 1: (0.2-0.4): (0.05 to 0.15), more preferably 1: (0.25-0.30): (0.08-0.09), specifically, in the embodiment of the invention, the ratio may be 1:0.25:0.09, or 1:0.30: 0.09.

After the mixed pellet is obtained, the mixed pellet is dried firstly and then is subjected to oxidizing roasting in an oxidizing atmosphere to obtain the oxidizing roasted pellet.

In the invention, the drying temperature is preferably 150-180 ℃, more preferably 160-170 ℃, and specifically, in the embodiment of the invention, the drying temperature can be 150 ℃ or 180 ℃; the drying time is preferably 100-120 min, more preferably 110-120 min, and specifically, in the embodiment of the present invention, may be 120 min.

Carrying out oxidizing roasting on the dried pellets in an oxidizing atmosphere, wherein the oxidizing atmosphere is preferably air;

in the invention, the oxidizing roasting temperature is preferably 1000-1500 ℃, more preferably 1100-1400 ℃, and most preferably 1200-1300 ℃; specifically, in the embodiment of the present invention, the temperature may be 1200 ℃ or 1300 ℃; the time of the oxidizing roasting is preferably 50-100 min, more preferably 60-90 min, most preferably 70-80 min, and specifically, in the embodiment of the present invention, may be 60min or 80 min.

The invention adds the dephosphorizing agent with the components of calcium carbonate and calcium fluoride in the oxidizing roasting process, the dephosphorizing agent reacts with the components in the iron ore under the oxidizing atmosphere to change the mineral components of the dephosphorizing agent, and simultaneously, the phosphorus originally existing in the iron ore generates a single phosphorus-containing mineral, the structure of the ore can be changed, and conditions are created for the reduction and dephosphorization of iron.

And carrying out reduction roasting on the pellets after the oxidation roasting in a reducing atmosphere to obtain the reduction roasted pellets.

In the present invention, the reducing atmosphere is preferably natural gas pyrolysis gas and/or water gas; the temperature of the reduction roasting is preferably 1100-1300 ℃, more preferably 1150-1200 ℃, and specifically, in the embodiment of the invention, the temperature can be 1150 ℃ or 1200 ℃; the time for the reduction roasting is preferably 150 to 200min, more preferably 160 to 180min, and specifically, in the embodiment of the present invention, the time may be 150min or 180 min.

In the invention, the pellets after reduction roasting are preferably cooled to room temperature under the condition of air isolation, and more preferably cooled to room temperature in a graphite box under the condition of air isolation to obtain the reduced pellets. The reducing ball needs to be cooled to room temperature under the condition of air isolation, and can be cooled by water or nitrogen as a medium.

After the reducing balls are obtained, the reducing balls are crushed to the particle size of below 2mm (-2mm), and then two-stage ore grinding-magnetic separation is carried out;

in the invention, the ore grinding magnetic separation is divided into two sections of ore grinding-magnetic separation (which means that the two sections of ore grinding magnetic separation comprise a first section and a second section);

first-stage grinding, and ball-milling the crushed reduced particles to-0.074 mm particle content of not less than 65%, such as 65% or 70%; then, carrying out primary magnetic separation, wherein the magnetic field intensity of the primary magnetic separation is preferably 1600-1800 oersted, and more preferably 1700-1800 oersted;

second-stage ore grinding is carried out to grind the magnetic part material after the first-stage magnetic separation until the content of particles with a particle size of-0.074 mm is not less than 85 percent, such as 85 percent or 95 percent; and then carrying out two-stage magnetic separation, wherein the magnetic field intensity of the two-stage magnetic separation is preferably 1300-1400 oersted, and more preferably 1400 oersted.

In the reduced iron product obtained by the process, the iron grade is more than 93 percent, the iron recovery rate is more than 92 percent, and the phosphorus content is less than 0.08 percent.

The invention provides a method for treating high-phosphorus oolitic iron ore, which comprises the following steps: A) mixing the high-phosphorus oolitic iron ore, a dephosphorizing agent and water, and pressing into balls to obtain mixed balls; the dephosphorization agent comprises calcium carbonate and calcium fluoride, wherein the mass ratio of the calcium carbonate to the calcium fluoride is 1: (0.15 to 0.30); B) drying the mixed pellets and then carrying out oxidation roasting to obtain oxidation-roasted pellets; C) carrying out reduction roasting on the oxidized and roasted pellets in a reducing atmosphere to obtain reduced pellets; D) and (3) cooling the reduced pellets to room temperature in an air-isolated mode, and then carrying out ore grinding-magnetic separation to obtain a reduced iron product. The pellet is added with the dephosphorizing agent, the dephosphorizing agent reacts with components in the ore under the oxidizing atmosphere to change the mineral components of the pellet, and meanwhile, phosphorus originally existing in the iron mineral is generated into a single phosphorus-containing mineral, the structure of the ore can be changed, and conditions are created for reduction and dephosphorization of iron. The method has the advantages of simple process flow, high removal rate of phosphorus in the high-phosphorus oolitic iron ore, high iron grade and recovery rate of the obtained powder reduced iron, and no influence on the reduction effect due to the change of the iron grade and phosphorus content of the raw ore in a certain range.

For further illustration of the present invention, the following will describe the method for treating high phosphorus oolitic iron ore in detail with reference to the following examples, which should not be construed as limiting the scope of the present invention.

Example 1

Taking high-phosphorus oolitic hematite with the granularity of less than 1mm, the iron grade of 55.81 percent and the phosphorus content of 0.72 percent as raw ore, and adding 25 percent of dephosphorizing agent (CaCO)₃With CaF₂Calcium fluoride with the mass ratio of 1:0.15) and 9 percent of water are evenly mixed and pressed into balls on a ball pressTo obtain mixed pellets; drying the mixed pellets at 150 ℃ for 120min, and then oxidizing and roasting at 1200 ℃ for 60 min; introducing water gas at 1150 ℃ for reduction for 150min, and placing the product in a graphite box to isolate air and cool the product to room temperature to obtain reduction balls; crushing the reducing balls to-1 mm, and performing two-stage ore grinding-magnetic separation to obtain powder reduced iron, wherein the ore grinding at the first stage is carried out until the ore grinding at the-200 meshes accounts for 65%, and the magnetic field intensity at the first stage is 1800 oersted; the second-stage grinding is carried out until the ore accounts for 85 percent in a range of-200 meshes, and the magnetic field intensity of the second-stage magnetic separation is 1400 oersted.

Finally, the obtained powdery reduced iron has the iron grade of 96.55 percent, the iron recovery rate of 94.99 percent and the phosphorus content of 0.08 percent.

Example 2

Taking high-phosphorus oolitic hematite with the granularity of less than 1mm, the iron grade of 43.65 percent and the phosphorus content of 0.83 percent as raw ore, and adding 30 percent of dephosphorizing agent (CaCO)₃With CaF₂Calcium fluoride with the mass ratio of 1:0.30) and 9% of water are uniformly mixed and pressed into balls on a ball press to obtain mixed balls; drying the mixed pellets at 180 ℃ for 120min, and then oxidizing and roasting at 1300 ℃ for 80 min; introducing water gas at 1200 ℃ for reduction for 180min, and then placing the graphite box in a graphite box to isolate air and cool the graphite box to room temperature to obtain reduction balls; crushing the reducing balls to-1 mm, and performing two-stage ore grinding-magnetic separation to obtain powder reduced iron, wherein the ore grinding at the first stage is carried out until the ore grinding at the-200 meshes accounts for 70%, and the magnetic field intensity at the first stage is 1800 oersted; the second-stage grinding is carried out until the ore accounts for 95 percent in a range of-200 meshes, and the magnetic field intensity of the second-stage magnetic separation is 1400 oersted.

The final obtained powdered reduced iron has an iron grade of 93.28%, an iron recovery rate of 92.30% and a phosphorus content of 0.07%.

Comparative example 1

Taking high-phosphorus oolitic hematite with the granularity of less than 1mm, the iron grade of 43.65% and the phosphorus content of 0.83% as raw ore, adding only 9% of water without adding a dephosphorizing agent, uniformly mixing, and pressing into balls on a ball press to obtain mixed balls; drying the mixed pellets at 180 ℃ for 120min, and then oxidizing and roasting at 1300 ℃ for 80 min; introducing water gas at 1200 ℃ for reduction for 180min, and then placing the graphite box in a graphite box to isolate air and cool the graphite box to room temperature to obtain a reduction ball; crushing the reducing balls to-1 mm, and performing two-stage ore grinding-magnetic separation to obtain powder reduced iron, wherein the ore grinding at the first stage is carried out until the ore grinding at the-200 meshes accounts for 75%, and the magnetic field intensity at the first stage is 1800 oersted; the second-stage grinding is carried out until the ore accounts for 90 percent in a range of-200 meshes, and the magnetic field intensity of the second-stage magnetic separation is 1400 oersted.

Finally, the obtained powdered reduced iron has the iron grade of 92.35 percent, the iron recovery rate of 91.48 percent and the phosphorus content of 0.27 percent. It can be seen that the process can not produce reduced iron powder with a phosphorus content of less than 0.1% without the addition of a dephosphorizing agent.

Comparative example 2

Similarly, high phosphorus oolitic hematite with the granularity of less than 1mm, the iron grade of 43.65 percent and the phosphorus content of 0.83 percent is used as raw ore, and 20 percent of CaCO is added₃And 9% of water, uniformly mixing, and pressing into balls on a ball press to obtain mixed balls; drying the mixed pellets at 180 ℃ for 120min, and then oxidizing and roasting at 1300 ℃ for 80 min; introducing water gas at 1200 ℃ for reduction for 180min, and then placing the graphite box in a graphite box to isolate air and cool the graphite box to room temperature to obtain reduction balls; crushing the reducing balls to-1 mm, and performing two-stage ore grinding-magnetic separation to obtain powder reduced iron, wherein the ore grinding at the first stage is carried out until the ore grinding at the-200 meshes accounts for 70%, and the magnetic field intensity at the first stage is 1800 oersted; the second-stage grinding is carried out until the ore accounts for 95 percent in a range of-200 meshes, and the magnetic field intensity of the second-stage magnetic separation is 1400 oersted.

Finally, the obtained powdery reduced iron has the iron grade of 91.15 percent, the iron recovery rate of 89.24 percent and the phosphorus content of 0.17 percent. It can be seen that the addition of calcium carbonate as a dephosphorizing agent does not result in a reduced iron powder with a phosphorus content of less than 0.1%.

Comparative example 3

Taking high-phosphorus oolitic hematite with the granularity of less than 1mm, the iron grade of 43.65 percent and the phosphorus content of 0.83 percent as raw ore, and adding 30 percent of dephosphorizing agent (CaCO)₃With CaF₂Calcium fluoride with the mass ratio of 1:0.30) and 9% of water are uniformly mixed and pressed into balls on a ball press to obtain mixed balls; drying the mixed pellets at 180 ℃ for 120min, and then oxidizing and roasting at 1100 ℃ for 80 min; introducing water gas at 1050 ℃ for reduction for 180min, and then placing the graphite box in a graphite box to isolate air and cool the graphite box to room temperature to obtain a reduction ball; finally, theCrushing the reducing balls to-1 mm, and performing two-stage ore grinding-magnetic separation to obtain powder reduced iron, wherein the ore grinding at the first stage is carried out until the ore grinding at the-200 meshes accounts for 70%, and the magnetic field intensity at the first stage is 1800 oersted; the second-stage grinding is carried out until the ore accounts for 95 percent in a range of-200 meshes, and the magnetic field intensity of the second-stage magnetic separation is 1400 oersted.

Finally, the obtained powdered reduced iron has the iron grade of 89.21 percent, the iron recovery rate of 92.14 percent and the phosphorus content of 0.35 percent. It can be seen that the iron grade and phosphorus content of the reduced iron obtained at the gas reduction temperature of less than 1100 ℃ can not meet the required indexes.

Comparative example 4

Taking high-phosphorus oolitic hematite with the granularity of less than 1mm, the iron grade of 43.65 percent and the phosphorus content of 0.83 percent as raw ore, and adding 30 percent of dephosphorizing agent (CaCO)₃With CaF₂Calcium fluoride with the mass ratio of 1:0.30) and 9% of water are uniformly mixed and pressed into balls on a ball press to obtain mixed balls; drying the mixed pellets at 180 ℃ for 120min, and then oxidizing and roasting at 1150 ℃ for 80 min; introducing water gas at 1200 ℃ for reduction for 180min, and then placing the graphite box in a graphite box to isolate air and cool the graphite box to room temperature to obtain reduction balls; crushing the reducing balls to-1 mm, and performing two-stage ore grinding-magnetic separation to obtain powder reduced iron, wherein the ore grinding at the first stage is carried out until the ore grinding at the-200 meshes accounts for 70%, and the magnetic field intensity at the first stage is 1800 oersted; the second-stage grinding is carried out until the ore accounts for 95 percent in a range of-200 meshes, and the magnetic field intensity of the second-stage magnetic separation is 1400 oersted.

Finally, the obtained powdery reduced iron has the iron grade of 90.45 percent, the iron recovery rate of 90.12 percent and the phosphorus content of 0.16 percent. Therefore, the phosphorus content of the powder reduced iron is higher than 0.1 percent when the temperature of oxidizing roasting is reduced to be below 1200 ℃, and qualified products cannot be obtained.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.