CN106636521A - Method and system for improving grinding separation effect of reduced pellets containing metal iron - Google Patents

Abstract

The invention discloses a method and a system for improving the grinding and separation effect of reducing pellets containing metal iron. The present invention firstly provides a method for improving the effect of grinding and separating metal-containing iron reduction pellets, including: (1) preparing agglomerates mixed with iron-containing, calcium-containing and carbon-containing materials; (2) reducing the agglomerates at high temperature, Obtain reduced pellets containing metallic iron; (2) water-quench the reduced pellets containing metallic iron, add grinding additives for wet grinding to obtain ore pulp; (3) perform solid-liquid separation on the ore pulp to obtain filter residue and filtrate (4) The filter residue is physically sorted to obtain iron-containing particles and tailings; (5) The tailings are used to prepare cement. The present invention further provides a dedicated system for realizing the above method. The method and system of the invention can not only improve the effect of grinding and separation of metal-containing iron reduction pellets, increase the iron grade and iron recovery rate of iron products, but also effectively reduce the energy consumption and steel consumption of grinding.

Description

A method and system for improving the grinding and separation effect of metallic iron-containing reduction pellets

technical field

The present invention relates to a method for preparing ferroalloys, further relates to a method for improving the effect of grinding and separating metal-containing iron reduction pellets, and also relates to a system for improving the grinding and separation effect of metal-containing iron-containing reducing pellets, which belongs to the preparation of ferroalloys field.

Background technique

China is one of the countries rich in iron ore resources in the world. The proven reserves are 57.872 billion tons, and about 26 billion tons are available for development and utilization, but 97% are lean ore, and the average grade is only 33%. The average grade of the world's major iron ore supply countries is 20% lower. With the rapid development of China's iron and steel industry, the consumption of iron ore resources is accelerating, and China's iron ore resources can no longer meet the needs of steel production. Most large iron and steel enterprises in China have to import large quantities of iron ore for production. Since 2003, the iron ore import dependence has reached more than 50%. In addition, the world iron ore price is on the rise, which makes the development of China's steel industry face great difficulties. Therefore, it is imminent to develop high-efficiency utilization technology according to the characteristics of iron ore resources in China.

In recent years, for some iron-containing metallurgical waste residues, relevant Chinese scientific researchers have broken through the traditional concept of beneficiation-sintering-blast furnace process, and proposed to use the method of "reduction roasting-magnetic separation" to treat these metallurgical waste residues. The effective enrichment of iron and the comprehensive utilization of resources have been realized. After cold briquetting, the iron powder with high metallization rate obtained by this process can not only supplement the shortage of scrap steel resources, but also be a high-quality raw material for smelting high-quality steel and special steel.

The patent with the notification number CN200910094839.5A discloses a method for extracting iron from copper smelting waste slag. The method is to carry out mineral phase reconstruction and carbothermal reduction at high temperature after mixing copper slag, reducing agent, calcium oxide or calcium carbonate. Reaction, iron recovery after magnetic separation separation. The notification number is CN104404260A, which discloses a method for separating valuable metals from copper slag. The method undergoes two pelletizing and roasting. During the first pelletizing and roasting, fayalite is converted into easily reduced iron oxide. Ball roasting reduces iron oxide in copper slag to metallic iron and slag is separated by magnetic separation. However, the disadvantages of these technologies of reducing roasting from copper slag and recovering iron by magnetic separation are that the purity of the obtained iron powder product is not high, it can only be used as an ingredient for steelmaking, and further smelting is required, and the technical and economic indicators are not up to standard.

Therefore, it is of great economic value to find a method to improve the grinding and separation effect of metal-containing iron reducing pellets, and to increase the iron grade and iron recovery rate of iron products.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for improving the grinding and separation effect of metallic iron-containing reducing pellets, which can not only improve the grinding and separating effect of metallic iron-containing reducing pellets, but also improve The iron grade and iron recovery rate of iron products can also reduce grinding energy consumption and steel consumption.

In order to solve the problems of the technologies described above, the technical scheme that the present invention takes is:

The invention provides a method for improving the effect of grinding and separating metal-containing iron reduction pellets, comprising the following steps:

(1) preparing agglomerates mixed with iron-containing, calcium-containing and carbon-containing materials; (2) reducing the agglomerates at high temperature to obtain reduced pellets containing metallic iron; (2) reducing the reduced pellets containing metallic iron Carry out water quenching treatment, add ore grinding additives for wet grinding to obtain ore pulp; (3) solid-liquid separation of ore pulp to obtain filter residue and filtrate; (4) physical separation of filter residue to obtain iron-containing particles and tailings slag; (5) ) tailings slag to prepare cement.

The preparation of the agglomerate in step (1) includes: uniformly mixing the iron-containing material, the calcium-containing material, the carbon-containing material and the binder in proportion, and pelletizing or pressing to form.

The mass ratio of the iron-containing material, calcium-containing material, carbon-containing material and binder is 100:(3-40):(15-50):(0-10).

The iron-containing material can be copper slag, nickel slag, red mud, iron oxide scale, lead-zinc slag, laterite nickel ore, sulfuric acid slag, iron and steel smelting dust or iron ore (can be refractory ore and/or low-grade iron ore stone).

The total content of Al ₂ O ₃ and MgO in the impurities of the iron-containing material is lower than the total content of SiO ₂ and CaO. When the total content of Al ₂ O ₃ and MgO in the impurities of iron-containing materials is lower than the total content of SiO ₂ and CaO, it is beneficial to the formation of silicon-calcium compounds. When the total content of Al ₂ O ₃ and MgO is higher than that of SiO ₂ and the total content of CaO, it is not conducive to the formation of silicon-calcium compounds that can react with grinding additives. Preferably, among the impurities of the iron-containing material, the mass ratio of (Al ₂ O ₃ +MgO)/(SiO ₂ ) is lower than 1.0, such as lower than 0.8, lower than 0.5, or even lower than 0.1.

The calcium-containing material mainly contains any one or more of CaCO ₃ , Ca(OH) ₂ , CaO, CaCl ₂ or CaF ₂ .

The carbonaceous material is any one or a mixture of semi-coal, anthracite, lignite, bituminous coal, coking coal or graphite in any proportion. Preferably, the fixed carbon content of the carbonaceous material is ≥65%, and the ash content is ≤20%. When the fixed carbon content is less than 65%, it is not conducive to the full reduction of iron oxides to form metallic iron, which affects the subsequent separation and recovery operations. When the ash content is greater than 20%, more impurities are brought into the pellets, which affects the aggregation of iron particles. Dacheng coarse-grained iron makes the final iron product iron grade not high.

The binder is mainly one or more of bentonite, clay, water glass, red mud, asphalt, sodium carboxymethylcellulose (CMC), starch, modified starch, sodium humate or dextrin The combination.

In order to make the pellets simultaneously generate silicon-calcium compounds during the reduction process, that is, any one or more of calcium orthosilicate, wollastonite, calcium silicate, dicalcium silicate or tricalcium silicate in any proportion mixture, the present invention adjusts the raw material conditions and reduction conditions. Finally, it is shown that by adding calcium-containing raw materials to adjust the proportion of Al ₂ O ₃ , MgO, SiO ₂ , and CaO in the pellets, silicon-calcium compounds are formed when the pellets are reduced at 1150°C to 1400°C at high temperature. If the reduction temperature is too low (for example, the reduction temperature is lower than 1150° C.), it is not conducive to the formation of silicon-calcium compounds, and if the reduction temperature is too high (for example, the reduction temperature is higher than 1400° C.), the energy consumption is large and the cost is high. Most preferably, the reduction temperature for reducing the agglomerate at high temperature in step (2) is 1200-1350°C.

During the grinding process in step (2), wet grinding is performed after adding grinding additives. This is because the material is broken to produce a new interface, and the surface activity of the new interface is higher, and some chemical reactions are more likely to occur. The occurrence of chemical reactions can affect the breakage of the firmly bound bonds between adjacent atoms, promote the generation of new interfaces, and make the metal iron particles easier to separate from other minerals. Therefore, adding grinding additives for wet grinding, a series of chemical reactions between the grinding additives and the silicon-calcium compound in the slag phase can promote the separation of the metal iron particles from the slag phase substances on the surface, making the surface of the metal iron particles more pure and containing There are fewer impurity substances, and the iron grade of the obtained product is higher. At the same time, it can also promote the separation of fine-grained metallic iron in other mineral phases from the slag phase, making it easier to be separated and sorted and recovered, so the iron recovery rate is also improved.

The grinding additive is a strong base and weak acid salt; preferably, the strong base and weak salt is selected from any one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate in any proportion mixture. The added amount of the grinding additive is 0.5%-10% of the total weight of the reducing pellets. Grinding additives can be added in solid form or in solution or a combination of both.

The concentration of the pulp in the wet grinding is 50%-80%.

The solid-liquid separation described in step (3) is to filter or suction filter and rinse the ore slurry.

The physical separation described in step (4) includes magnetic separation or re-selection.

The preparation of cement from the tailings slag in step (5) is to add cement additives to the tailings slag, optimize the proportion of Al ₂ O ₃ , MgO, SiO ₂ , CaO and other components in the tailings slag, and calcinate to prepare cement clinker.

The present invention further provides a system for improving the grinding and separation effect of metal-containing iron reduction pellets, including: a forming device, the forming device has an inlet for iron-containing materials, an inlet for calcium-containing materials, an inlet for carbon-containing materials, and an inlet for binders and blob export;

A reducing device, the reducing device has a briquette inlet, a flue gas outlet and a reduced pellet outlet, and the briquette inlet is connected to the briquette outlet of the forming device;

A water quenching device, the water quenching device has a reduced pellet inlet, a water inlet and a water quenched pellet outlet, and the reduced pellet inlet is connected to the reduced pellet outlet of the reducing device;

A grinding device, the grinding device has a water quenching pellet inlet, a grinding additive inlet, a water inlet and a slurry outlet, and the water quenching pellet inlet is connected to the water quenching pellet outlet of the water quenching device;

A solid-liquid separation device, the solid-liquid separation device has a pulp inlet, a filter residue outlet and a filtrate outlet, and the pulp inlet is connected to the pulp outlet of the grinding device;

A physical separation device, the physical separation device has a filter residue inlet, an iron-containing particle outlet and a tailings residue outlet, and the filter residue inlet is connected to the filter residue outlet of the solid-liquid separation device;

A cement preparation device, the cement preparation device has a tailings slag inlet, an additive inlet for cement preparation and a cement clinker outlet, and the tailings slag inlet is connected with the tailings slag outlet of the physical separation device.

Wherein, the molding device includes a mixer and a ball press, or a mixer and a pelletizing disc; the reduction device is a conventional device with a reduction function, such as a rotary hearth furnace, a muffle furnace, a rotary kiln , tunnel kiln, etc.; the water quenching device is a water-sealed zipper machine; the grinding device is a ball mill, a rod mill; the solid-liquid separation device is a filter press or a vacuum filter; the physical separation device is A centrifugal separator or a magnetic separator; the cement preparation device is a cement rotary kiln.

Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

1. The grinding additive reacts with the silicon-calcium compound in the slag phase in the reducing pellets, which promotes the separation of the mineral phase on the surface of the metal iron particles and improves the iron grade of the obtained product.

2. Promote the separation of fine-grained iron particles in other mineral phases, so that they can be separated and recovered by sorting, which improves the iron recovery rate of the obtained product.

3. Improve the separation effect of the grinding process, shorten the grinding time, save grinding energy consumption, and also save the consumption of steel in the grinding equipment.

Description of drawings

Fig. 1 is a schematic diagram of a system for improving the grinding and separation effect of iron-containing reducing pellets according to the present invention.

Fig. 2 is a process flow diagram for improving the grinding and separation effect of metal-containing iron reducing pellets in the present invention.

detailed description

The present invention will be further described below in conjunction with specific embodiments, and the advantages and characteristics of the present invention will become clearer along with the description. However, these embodiments are only exemplary and do not constitute any limitation to the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the present invention can be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the protection scope of the present invention.

As shown in Figure 1, the present invention provides a system for improving the grinding and separation effect of metal-containing iron reduction pellets, including: a forming device S100, the forming device S100 has an iron-containing material inlet, a calcium-containing material inlet, and a carbon-containing material. inlet, binder inlet and briquette outlet;

A reducing device S200, the reducing device S200 has a pellet inlet, a flue gas outlet and a reduced pellet outlet, and the pellet inlet is connected to the pellet outlet of the forming device S100;

A water quenching device S300, the water quenching device S300 has a reduced pellet inlet, a water inlet and a water quenched pellet outlet, and the reduced pellet inlet is connected to the reduced pellet outlet of the reducing device S200;

The ore grinding device S400, the ore grinding device S400 has a water quenching pellet inlet, a grinding additive inlet, a water inlet and an ore pulp outlet, and the water quenching pellet inlet is connected to the water quenching pellet outlet of the water quenching device S300;

A solid-liquid separation device S500, the solid-liquid separation device S500 has a pulp inlet, a filter residue outlet and a filtrate outlet, and the pulp inlet is connected to the pulp outlet of the grinding device S400;

A physical separation device S600, the physical separation device S600 has a filter residue inlet, an iron-containing particle outlet and a tailings residue outlet, and the filter residue inlet is connected to the filter residue outlet of the solid-liquid separation device S500;

The cement preparation device S700, the cement preparation device S700 has a tailings slag inlet, an additive inlet for cement preparation and a cement clinker outlet, and the tailings slag inlet is connected with the tailings slag outlet of the physical separation device S600.

Further, the present invention provides a method for improving the grinding and separation effect of metal-containing iron-containing reduction pellets by using the above-mentioned system, which includes the following steps:

(1) Feed iron-containing materials, calcium-containing materials, carbon-containing materials, and binders into the molding device S100 through the inlets of iron-containing materials, calcium-containing materials, carbon-containing materials, and binders, and prepare a dough lumps, discharged through the lump outlet;

(2) The agglomerate enters the reduction device S200 through the agglomerate inlet of the reduction device S200 for reduction to obtain reduced pellets, and the reduced pellets are discharged through the outlet of the reduced pellets;

(3) The reduced pellets and water enter the water quenching device S300 through the inlet of the water quenching device S300 respectively to obtain water quenching pellets, which are discharged through the outlet of the water quenching pellets;

(4) water quenching pellets, grinding additives and water enter into the grinding device S400 through the inlet of the grinding device S400 respectively, and the obtained pulp is discharged from the pulp outlet;

(5) The ore pulp enters the solid-liquid separation device S500 through the inlet of the solid-liquid separation device S500 to obtain filter residue and filtrate, which are discharged from the filter residue outlet and the filtrate outlet respectively;

(6) The filter residue enters the physical separation device S600 through the entrance of the physical separation device S600, and obtains iron-containing particles and tailings slag, which are discharged from the iron-containing particle outlet and the tailings slag outlet respectively;

(7) The tailings slag and the additives for preparing cement respectively enter the cement preparation device S700 through the inlet of the cement preparation device S700 to obtain cement clinker, which is discharged from the cement clinker outlet.

Below with reference to Fig. 1, 2, the method for improving the grinding separation effect of metal-containing iron reducing pellets in actual production is introduced in detail, specifically see embodiment 1-3:

Example 1

Copper slag (containing TFe 39.75%, SiO ₂ 33.18%, CaO 2.75%, Al ₂ O ₃ 2.31%, MgO 2.07%, Cu0.27%), limestone (CaO 50.04%), semi-coke (fixed carbon 74.46%, ash content 12%), composite binder (bentonite 20%+modified starch 8%+water 72%), by weight ratio, copper slag: limestone: blue carbon: composite binder=100:15: 25:10 for ingredients. After the mixture is mixed evenly, it is pelletized and dried. The dried pellets were reduced and roasted at 1350°C for 30 minutes. After roasting, the pellets were quenched in water, and 10% sodium bicarbonate was added for wet grinding. The pulp concentration was 50%, and the ore was ground for 30 minutes. The pulp is filtered by suction, rinsed with water, and the filtrate is collected. After the filtrate is concentrated and purified, it is returned to the grinding for reuse. The filter residue is sorted by a centrifugal concentrator with a rotating speed of 500r/min to obtain copper-iron alloy powder with an iron content of 93.45%, an iron recovery rate of 92.18%, and a copper content of 0.52%.

Example 2

The smelting raw materials are iron and steel smelting dust (containing TFe 56.01%, SiO ₂ 7.11%, CaO 1.86%, Al ₂ O ₃ 0.35%, MgO 0.31%), quicklime (CaO 98.3%), coking coal (fixed carbon 65%, ash 20% ), according to the weight ratio, metallurgical dust: quicklime: coking coal = 100:3:50 for batching. Press the ball after mixing the mixture. The pellets were reduced and roasted at 1200°C for 90 minutes. After roasting, the pellets were water-quenched, and 0.5% sodium carbonate was added for wet grinding. The pulp concentration was 80%, and the grinding was performed for 30 minutes. The pulp is filtered by suction, rinsed with water, and the filtrate is collected. After the filtrate is concentrated and purified, it is returned to the grinding for reuse. The filter residue is sorted by a centrifugal concentrator with a rotating speed of 700r/min, and the obtained iron product is magnetically separated under a magnetic field strength of 100mT, and finally a metal iron powder with an iron content of 95.31% is obtained, and the iron recovery rate is 94.22%. The tailings residue is suction-filtered and dried. Used to make cement.

Example 3

The smelting raw materials are low-grade refractory iron ore (containing TFe 43.63%, SiO ₂ 22.1%, CaO 3.58%, Al ₂ O ₃ 4.31%, MgO 0.59%), slaked lime (CaO 73.14%), anthracite (fixed carbon 85.43% , Ash content 7.66%), by weight, iron ore: slaked lime: anthracite: sodium carboxymethyl cellulose=100:40:15:0.5 carries out batching. After mixing the mixture, press the balls and dry them. The dried pellets were reduced and roasted at 1250°C for 45 minutes. After roasting, the pellets were water-quenched, and 3% potassium carbonate was added for wet grinding. The pulp concentration was 67%, and the grinding was performed for 30 minutes. The pulp is filtered by suction, rinsed with water, and the filtrate is collected. After the filtrate is concentrated and purified, it is returned to the grinding for reuse. The filter residue is sorted by a centrifugal concentrator with a rotating speed of 600r/min to obtain metal iron powder with an iron content of 93.41% and an iron recovery rate of 92.28%. The tailings residue is suction-filtered and dried for making cement.

Comparative Example 1

Compared with Example 1, other conditions are the same, only when no grinding additive is added during the ore grinding process (i.e. without adding 10% sodium bicarbonate of sodium), the iron grade of the obtained iron powder is 89.72%, and the iron recovery rate is 84.36%.

Comparative Example 2

Compared with Example 2, the other conditions are the same, except that when no grinding additive is added during the grinding process (that is, no 0.5% sodium carbonate is added), the iron grade of the obtained iron powder is 91.16%, and the iron recovery rate is 92.46%.

Comparative Example 3

Compared with Example 3, other conditions are the same, except that no grinding additives (that is, no 3% potassium carbonate) are added during the grinding process, the iron grade of the obtained iron powder is 90.88%, and the iron recovery rate is 88.49%.

Claims (10)

1. A method for improving the grinding separation effect of metal-containing iron reduction pellets is characterized in that, comprising the following steps: (1) preparing agglomerates mixed with iron-containing materials, calcium-containing materials, carbon-containing materials and binders; (2) reducing the agglomerates at high temperature to obtain reduced pellets containing metallic iron; The reduced pellets of metal iron are subjected to water quenching treatment, and grinding additives are added for wet grinding to obtain ore pulp; (3) the slurry is subjected to solid-liquid separation to obtain filter residue and filtrate; (4) filter residue is subjected to physical separation to obtain iron-containing particles and tailings. 2. The method according to claim 1, characterized in that: the preparation of the agglomerates comprises: uniformly mixing iron-containing materials, calcium-containing materials, carbon-containing materials and binders in proportion, and pelletizing or pressing into shapes. 3. according to the described method of claim 2, it is characterized in that: the mass ratio of described iron-containing material, calcium-containing material, carbon-containing material and binding agent is 100: (3-40): (15-50): (0-10). 4. The method according to claim 2 or 3, characterized in that the total content of Al ₂ O ₃ and MgO in the impurities of the iron-containing material is lower than the total content of SiO ₂ and CaO. 5. according to the described method of claim 1, it is characterized in that: described ore grinding additive is strong base weak acid salt; Preferably, described strong base weak acid salt is selected from sodium carbonate, sodium bicarbonate, potassium carbonate, carbonic acid A mixture of any one or more of potassium hydrogen in any proportion. 6. The method according to claim 1, characterized in that: the added amount of the grinding additive is 0.5%-10% of the total mass of the reduced pellets. 7. The method according to claim 1, characterized in that: the concentration of the pulp in step (2) is 50%-80%. 8. The method according to claim 1, characterized in that: the solid-liquid separation is to filter or suction filter the pulp and rinse; the physical separation includes magnetic separation or gravity separation. 9. A system for improving the grinding and separation effect of metal-containing iron reduction pellets, characterized in that it includes: A forming device having an inlet for iron-containing materials, an inlet for calcium-containing materials, an inlet for carbon-containing materials, an inlet for binders, and an outlet for agglomerates; A reducing device, the reducing device has a briquette inlet, a flue gas outlet and a reduced pellet outlet, and the briquette inlet is connected to the briquette outlet of the forming device; A water quenching device, the water quenching device has a reduced pellet inlet, a water inlet and a water quenched pellet outlet, and the reduced pellet inlet is connected to the reduced pellet outlet of the reducing device; A grinding device, the grinding device has a water quenching pellet inlet, a grinding additive inlet, a water inlet and a slurry outlet, and the water quenching pellet inlet is connected to the water quenching pellet outlet of the water quenching device; A solid-liquid separation device, the solid-liquid separation device has a pulp inlet, a filter residue outlet and a filtrate outlet, and the pulp inlet is connected to the pulp outlet of the grinding device; A physical separation device, the physical separation device has a filter residue inlet, an iron-containing particle outlet and a tailings residue outlet, and the filter residue inlet is connected to the filter residue outlet of the solid-liquid separation device; A cement preparation device, the cement preparation device has a tailings slag inlet, an additive inlet for cement preparation and a cement clinker outlet, and the tailings slag inlet is connected with the tailings slag outlet of the physical separation device. 10. The system according to claim 9, characterized in that, the forming device is a mixer and a ball press, or a mixer and a pelletizing disc; the reducing device is a rotary hearth furnace, a muffle furnace, rotary kiln or tunnel kiln; the water quenching device is a water-sealed zipper machine; the grinding device is a ball mill or rod mill; the solid-liquid separation device is a filter press or a vacuum filter; The separation device is a centrifugal separator or a magnetic separator; the cement preparation device is a cement rotary kiln.