阅读说明：本技术 一种采用烧结法实现含铬废渣复合球团资源化利用的方法 (Method for realizing resource utilization of chromium-containing waste residue composite pellets by adopting sintering method ) 是由 张元波 苏子键 涂义康 姜涛 李光辉 范晓慧 彭志伟 饶明军 朱应贤 刘硕 刘继 于 2020-12-31 设计创作，主要内容包括：本发明公开了一种采用烧结法实现含铬废渣复合球团资源化利用的方法,该方法是将包括含铬废渣及还原剂在内的原料混合造球,得到球团料；同时,将包括铁矿、熔剂及焦粉在内的原料混匀制粒,得到颗粒料；再将球团料和颗粒料混合后分层布料到烧结机上进行烧结,即得含铬烧结矿,充分利用球团料的结构优势以及料层的自动蓄热作用和颗粒料的热场加热球团料,使球团料中的高价铬化合物在高温条件下快速还原为金属铬或碳化铬,实现含铬废渣的彻底解毒,且同时得到性能优异的含铬烧结矿,可用作含铬铁水或铬铁合金冶炼优质炉料,该方法实现含铬废渣的资源化利用,易于实现工业化,具有良好的应用前景。(The invention discloses a method for realizing resource utilization of chromium-containing waste residue composite pellets by adopting a sintering method, which comprises the steps of mixing raw materials including chromium-containing waste residue and a reducing agent for pelletizing to obtain pellet materials; meanwhile, uniformly mixing raw materials including iron ore, flux and coke powder, and granulating to obtain granules; the method is characterized in that the method comprises the steps of mixing pellets and granules, then distributing the mixture on a sintering machine in a layering manner, sintering the mixture to obtain chromium-containing sintered ore, fully utilizing the structural advantages of the pellets, automatically storing heat of a material layer and heating the pellets by a thermal field of the granules, and quickly reducing a high-valence chromium compound in the pellets into metal chromium or chromium carbide under a high-temperature condition, so that the chromium-containing waste residue is thoroughly detoxified, and meanwhile, the chromium-containing sintered ore with excellent performance is obtained and can be used as a high-quality furnace charge for smelting chromium-containing water or chromium-iron alloy.)

1. A method for realizing resource utilization of chromium-containing waste residue composite pellets by adopting a sintering method is characterized by comprising the following steps of: mixing raw materials including chromium-containing waste residues and a reducing agent for pelletizing to obtain a pellet material; meanwhile, uniformly mixing raw materials including iron ore, flux and coke powder, and granulating to obtain granules; and mixing the pellet material and the granular material, and then distributing the mixture on a sintering machine in a layering manner for sintering to obtain the chromium-containing sintered ore.

2. The method for realizing resource utilization of the chromium-containing waste residue composite pellets by adopting the sintering method as claimed in claim 1, which is characterized in that: the pelletizing comprises the following steps:

1) mixing anthracite, binder and water to obtain a mixed material A;

2) mixing chromium-containing waste residue, coke powder, a binder and water to obtain a mixed material B;

3) mixing anthracite, binder and water to form a mixed material C;

4) firstly, preparing the mixed material A into a ball core, then adding the mixed material B to wrap the ball core to form a middle layer wrapping the ball core, and then adding the mixed material C to wrap the outer layer to obtain the pellet material with a multilayer wrapped ball body structure.

3. The method for realizing resource utilization of the chromium-containing waste residue composite pellets by adopting the sintering method as claimed in claim 2, which is characterized in that: in the mixed material B, the mass ratio of carbon in the coke powder to oxygen in the chromium-containing waste residue is (0.4-0.6): 1.

4. The method for realizing resource utilization of the chromium-containing waste residue composite pellets by adopting the sintering method as claimed in claim 2, which is characterized in that: the diameter of the ball core is 1-3 mm, the diameter of the ball core coated with the middle layer is 4-9 mm, and the diameter of the final pellet is controlled to be 5-12 mm.

5. The method for realizing resource utilization of the chromium-containing waste residue composite pellets by adopting the sintering method as claimed in claim 2, which is characterized in that: the compression strength of the pellet material is not lower than 10N/pellet material, the falling strength is not less than 5 times/(0.5 m.times), and the bursting temperature is not lower than 400 ℃.

6. The method for realizing resource utilization of the chromium-containing waste residue composite pellets by adopting the sintering method according to claim 1 or 2, which is characterized by comprising the following steps of: the chromium-containing waste residue is at least one of chromium salt residue, ferrochromium residue, stainless steel pickling mud, electric furnace dust and chromium-containing electroplating sludge.

7. The method for realizing resource utilization of the chromium-containing waste residue composite pellets by adopting the sintering method as claimed in claim 1, which is characterized in that: the iron ore, the flux and the fuel in the granular material consist of (82-95%) by mass: (2-8%): (3% -10%); the particle size of the particle material comprises the following components: the particle size is less than 3mm, the mass ratio is 20-50%, the particle size is within the range of 3-5 mm, the mass ratio is 20-40%, the particle size is more than 5mm, and the mass ratio is 10-60%.

8. The method for realizing resource utilization of the chromium-containing waste residue composite pellets by adopting the sintering method according to claim 1 or 7, which is characterized by comprising the following steps of: the iron ore is at least one of chromite, laterite-nickel ore, magnetite and hematite.

9. The method for realizing resource utilization of the chromium-containing waste residue composite pellets by adopting the sintering method as claimed in claim 1, which is characterized in that: the mass percentage composition of the pellet material and the particle material is (20-50%): (80% to 50%).

10. The method for realizing resource utilization of the chromium-containing waste residue composite pellets by adopting the sintering method according to claim 1 or 9, which is characterized by comprising the following steps of: the layered material distribution is divided into three layers, and the distribution mass proportion of the pellet material in the upper layer, the middle layer and the lower layer of the material layer is controlled to be (50-60%): (20-30%): (10% to 20%).

Technical Field

The invention relates to a method for resource utilization of chromium-containing waste residues, in particular to a method for realizing thorough detoxification of the chromium-containing waste residues and obtaining high-quality chromium-containing composite sintered ores by utilizing the chromium-containing waste residues in a synergistic manner in an iron ore sintering process, and belongs to the technical field of metallurgical environmental protection.

Background

China is the largest chromium resource consuming country in the world, the chromium consumption is over one third of the world chromium-containing raw material yield, but the annual output of the chromium-containing raw material in China is less than 1% of the world annual output, the huge demand makes chromium become one of the metals with the highest external dependence in China, and the contradiction between supply and demand is quite prominent. In addition, with the continuous development of chromium ore resources, the high-quality lump ore resources are continuously reduced. At present, about 80% of annual mining amount of chromium ores in the world is fine ores, however, excessive fine ores directly fed into a furnace for smelting cause poor permeability of furnace charge, deteriorated furnace condition and slag turning, and various technical and economic indexes are seriously influenced. Therefore, the agglomeration treatment of chromium-containing raw materials is becoming an indispensable link in ferrochrome production.

The agglomeration treatment method of chromium ore mainly includes briquetting method, pelletizing method and sintering method. In the agglomeration process of the chromium-containing raw material, compared with a briquetting method and a pelletizing method, the sintering method is adopted for production, and the electric furnace yield can be improved by 10-17%; and secondly, the sintered ore has high porosity and uniform granularity, can improve the air permeability of the electric furnace, is beneficial to improving the speed of reduction reaction and reducing the smelting power consumption. However, chromium spinel has a high melting point, is difficult to produce a low-melting liquid phase, and its sinterability depends mainly on the properties of gangue and the added flux, so that the production of chromium-containing raw materials by sintering methods also has the disadvantages of low yield, high burnup, poor strength of sintered ores, etc., and further improvement and perfection of sintering methods are required.

On the other hand, the annual production amount of chromium-containing waste slag in China is nearly million tons, the chromium content in the chromium slag is high (3% -7%), the chromium slag in China is mainly used for sintering ingredients, glass colorants, building material auxiliary materials and the like at present, the utilization rate is less than 10%, and the accumulated stock of the chromium slag exceeds 700 million tons. The chromium slag contains highly toxic hexavalent chromium, which is dangerous solid waste and brings huge environmental problems for stockpiling. And the chromium in the chromium slag is not effectively utilized, so that huge resource waste is caused. Therefore, the method improves the resource utilization level of the chromium slag, and has important significance for the green, healthy and sustainable development of the chromium industry.

In conclusion, if the chromium-containing waste slag and the sintering are combined and the traditional sintering process is improved, the method has important significance for resource utilization of the chromium slag and the sintering process.

Disclosure of Invention

Aiming at the defects of the prior method for recycling the chromium-containing waste residue, the invention aims to provide a method for recycling the chromium-containing waste residue composite pellets by adopting a sintering method, which provides a high-quality furnace charge for ferrochrome smelting while realizing the thorough detoxification of the chromium-containing waste residue through one-step sintering, provides a new way for the clean, efficient and large-scale disposal and utilization of the chromium-containing waste residue, and has wide application prospect.

In order to realize the technical purpose, the invention provides a method for realizing resource utilization of chromium-containing waste residue composite pellets by adopting a sintering method, which comprises the steps of mixing raw materials including chromium-containing waste residue and a reducing agent for pelletizing to obtain pellet materials; meanwhile, uniformly mixing raw materials including iron ore, flux and coke powder, and granulating to obtain granules; and mixing the pellet material and the granular material, and then distributing the mixture on a sintering machine in a layering manner for sintering to obtain the chromium-containing sintered ore.

The key point of the technical scheme is that the chromium-containing waste residue and the iron ore are respectively pelletized and granulated, and are mixed and matched for material distribution, so that the pellet material can be heated by fully utilizing the automatic heat storage function of a material layer and the thermal field of the pellet material, a required proper temperature is provided for reduction of high-valence chromium in the chromium-containing waste residue, and good bonding between the pellet material and the pellet material is realized; meanwhile, the high-valence chromium compound in the chromium-containing waste residue is directly reduced into metal chromium or chromium carbide under the high-temperature condition by utilizing the strong reduction effect of carbon matched in the pellets, so that high-quality chromium-iron-containing sintered ore is obtained.

As a preferred scheme, the pelletizing comprises the following steps: 1) mixing anthracite, binder and water to obtain a mixed material A; 2) mixing chromium-containing waste residue, coke powder, a binder and water to obtain a mixed material B; 3) mixing anthracite, binder and water to form a mixed material C; 4) firstly, preparing the mixed material A into a ball core, then adding the mixed material B to wrap the ball core to form a middle layer wrapping the ball core, and then adding the mixed material C to wrap the outer layer to obtain the pellet material with a multilayer wrapped ball body structure. The prepared pellet material uses anthracite to prepare the pellet core and the outer coating layer, so that the intermediate layer is ensured to be in a stronger reducing atmosphere in the roasting process, and the intermediate layer adopts the coke powder with higher fixed carbon content, so that the carbothermic reduction of the chromium slag is ensured. Through double reinforcement, the three-layer pellet structure ensures the full reduction of the chromium-containing waste slag. The binder adopted in the preparation process of the pellet material is at least one of bentonite, humic acid, starch and other common binders for pellets. The addition amounts of water, binder and the like are conventional addition amounts in the pelletizing process.

As a preferable scheme, in the mixed material B, the mass ratio of carbon element in the coke powder to oxygen element in the chromium-containing waste residue is (0.4-0.6): 1. Preferably, the mass ratio of carbon in the coke powder to oxygen in the chromium-containing waste residue is (0.5-0.6): 1, so that the full reduction of high-valence chromium can be ensured.

As a preferable scheme, the diameter of the ball core is 1-3 mm, the diameter of the ball core coated with the middle layer is 4-9 mm, and the diameter of the final pellet material is controlled to be 5-12 mm. Preferably, the diameter of the ball core is 2-3 mm, the diameter of the ball core coated with the middle layer is 6-8 mm, and the diameter of the final pellet is controlled to be 8-12 mm.

As a preferable scheme, the compression strength of the pellet material is not lower than 10N/pellet, the falling strength is not less than 5 times/(0.5 m.times), and the bursting temperature is not lower than 400 ℃.

Preferably, the chromium-containing waste residue is at least one of chromium salt residue, ferrochromium residue, stainless steel pickling mud, electric furnace dust and chromium-containing electroplating sludge. The chromium-containing waste residue is common in the prior art and is suitable for preparing chromium-containing sinter ore by the method.

As a preferable scheme, the mass percentage composition of the iron ore, the fusing agent and the fuel in the granular material is (82% -95%): (2-8%): (3% to 10%). More preferably, the mass percentage composition of the iron ore, the flux and the fuel in the granular material is (85-93%): (3-7%): (4% to 8%).

As a preferred scheme, the particle size of the granule material is as follows: the particle size is less than 3mm, the mass ratio is 25-45%, the particle size is within the range of 3-5 mm, the mass ratio is 30-40%, the particle size is more than 5mm, and the mass ratio is 15-45%.

As a preferred scheme, the iron ore is at least one of chromite, laterite-nickel ore, magnetite and hematite.

As a preferable scheme, the mass percentage of the pellet materials and the particle materials is (20-50%): (80% to 50%). Preferably, the mass percentage composition of the pellet material and the particle material is (30-40%): (70% -60%).

As a preferable scheme, the layered cloth is divided into three layers, and the distribution mass proportion of the pellet material in the upper, middle and lower layers of the material layer is controlled to be (50% -60%): (20-30%): (10% to 20%). The carbon-containing pellets on the middle and upper layers have high proportion, generate more heat during combustion, strengthen the automatic heat storage function and contribute to reducing solid fuel consumption. Preferably, the distribution mass ratio of the pellet materials in the upper, middle and lower layers of the material layer is 55%: 25%: 20 percent.

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

the invention provides a new idea for cooperatively treating chromium-containing waste residues and carbon-containing waste materials in the iron ore sintering process, wherein the chromium-containing waste residues and a reducing agent are prepared into pellets and mixed with granules prepared from iron ore raw materials to be sintered in a sintering machine, the spherical materials can be heated by fully utilizing the automatic heat storage of a sintering material layer and the thermal field of the granules in the sintering process, the roasting temperature of the whole sphere can be obviously improved, and meanwhile, the strong reduction effect of the reducing agent which is internally matched with the pellets and used for fixing carbon in a high proportion can be utilized to ensure that the inside of the spherical materials is in a strong reducing atmosphere, so that high-valence chromium in the chromium-containing waste residues is directly reduced into metal chromium or chromium carbide under the high-temperature condition, thereby realizing the thorough detoxification of the chromium-containing waste residues in the iron ore sintering process, obtaining high-quality chromium-containing sintered ores and providing high-quality furnace charges for smelting chromium.

The optimized scheme of the invention optimizes the structure of the chromium-containing waste residue composite pellet material, and strictly controls the proportion of the pellet material in the upper layer, the middle layer and the lower layer of the sintering machine during layered material distribution, thereby bringing better optimization effect. In the sintering process, on one hand, the oxygen content in the pellet is low, the volatile content of the anthracite is high, the anthracite is incompletely combusted to generate carbon monoxide, so that a gas-solid indirect reduction process exists in the reduction roasting process of the chromium-containing waste residue, the reduction speed is greatly improved, and meanwhile, the contact probability of the chromium-containing waste residue and the carbon monoxide is improved in the process of diffusing the carbon monoxide generated by the reaction of the inner layer of the pellet to the outer layer of the pellet, so that the utilization rate of the carbon monoxide is improved. On the other hand, during sintering, the coke powder in the middle ball layer is directly contacted with the chromium-containing waste slag to generate direct reduction reaction, the fixed carbon content of the coke powder is high, and the full reduction of the chromium-containing waste slag is further ensured. In addition, when sintering, the burning of anthracite in the outer layer of the pellet, the automatic heat storage of the material layer and the thermal field of the particle material heat the pellet, which can obviously improve the roasting temperature of the whole sphere, improve the thermodynamic condition, simultaneously ensure the strong reducing atmosphere of the whole pellet and promote the rapid and complete reduction of chromium-containing waste residues. In general, the invention can maximize the efficiency of each layer of carbon and obviously reduce the carbon addition amount by optimizing the carbon distribution. More importantly, the chromium-containing waste residue contains higher calcium oxide, which is beneficial to the generation of liquid phase in a system and improves the caking property of sinter, so that the addition of the chromium-containing waste residue improves the sintering quality index of the iron-containing raw material to a certain extent.

The method realizes the complete detoxification of the chromium-containing waste residue by one step in the iron ore sintering process, improves the quality index of the iron-containing raw material, provides high-quality furnace charge for ferrochrome smelting, provides a new way for the clean, efficient and large-scale disposal and utilization of the chromium-containing waste residue, and has wide application prospect.

Detailed Description

The present invention will be described in detail with reference to the following embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by those skilled in the art without any inventive work based on the embodiments of the present invention are within the scope of the present invention.

In order to avoid repetition, the chromium slag and the iron-containing raw material related to the present specific embodiment are described in a unified manner as follows, and are not described in detail in the specific embodiment:

the chromium-containing waste residue comprises the following components in percentage by mass:

SiO₂8.58 to 14.51 wt%, 3.95 to 24.87 wt% MgO, Fe₂O₃7.54-14.30 wt% of Al₂O₃2.43-8.02 wt%, CaO 3.47-33.75 wt%, and Cr₂O₃The content is 2.23-10.90 wt%, and the content of hexavalent chromium is 1-3 wt%.

The chromite comprises the following components in percentage by mass:

SiO₂0.15 to 5.26 weight percent of MgO, 5.24 to 10.32 weight percent of FeO, 16.28 to 26.97 weight percent of Al₂O₃5.43-14.47 wt%, CaO 0.95-4.36 wt%, and Cr₂O₃The content is 59.36-64.75 wt%.

The laterite-nickel ore comprises the following components in percentage by mass:

SiO₂2.25 to 3.62 wt%, MgO 0.57 to 2.42 wt%, Fe₂O₃40.15-50.21 wt% of Al₂O₃4.32 to 7.58 wt%, CaO 0.02 to 0.25 wt%, and Cr₂O₃The content is 2.36-4.29 wt%.

The magnetite, the hematite, the flux, the coke powder, the anthracite, the bentonite, the humic acid and the like are all used raw materials for conventional sintering pellets.

Example 1

The chromium-containing waste slag, a reducing agent and a binder are mixed uniformly to prepare chromium slag composite pellets, iron ore, a flux, coke powder and the like are mixed uniformly to prepare granular materials, and the composite pellets and the granular materials are distributed on a sintering machine layer by layer to be roasted to obtain chromium-containing sintered ore.

The chromium-containing waste slag is chromium salt slag, the reducing agent is coke powder and anthracite, the binder is bentonite (the addition amount is about 1 percent of that of the pellet), the iron ore in the granular material is chromite, and the flux is quicklime.

In the composite pellet interlayer, the mass ratio of the carbon element of the coke powder to the oxygen element of the chromium slag is 0.5: 1.

The diameter of the inner sphere is 2mm, the diameter of the middle sphere is 6mm, and the diameter of the pellet is 10 mm.

The pelletizing time of the composite pellets is 12min, and the rotating speed of the pelletizing machine is 20 r/min.

The green pellet compressive strength of the chromium slag composite pellet is 13.5N/pellet, the falling strength is 8.6 times/(0.5 m.pellet), and the bursting temperature is 600 ℃.

The mass percentage composition of iron ore, flux and fuel in the granular material is 88.1%: 5.5%: 6.4 percent, uniformly mixing the iron ore, the fusing agent, the fuel and the water, and then performing a roller granulator, wherein the rotating speed of a roller is 23r/min, and the granulation time is 5 min.

The particle size of the particle material comprises the following components: -3mm (40.5%), 3-5 mm (34.3%) +5mm (25.2%).

The mass ratio of the composite pellets to the granules is 30%: 70 percent.

The layered material distribution, namely the control of the proportion of the composite pellet material in the upper layer, the middle layer and the lower layer of the sintering machine is 55 percent respectively: 25%: 20 percent.

In example 1, the sintering rate was 26.83 mm/min^-1The yield was 73.48%, the drum strength was 60.35%, and the utilization factor was 1.320t (m)²·h)^-1. The hexavalent chromium content in the obtained sintering ore is 0.0001% (less than the national discharge standard of 0.0005%), thereby realizing one-step detoxification and resource utilization of the chromium slag.

Example 2

The chromium-containing waste slag, a reducing agent and a binder are mixed uniformly to prepare chromium slag composite pellets, iron ore, a flux, coke powder and the like are mixed uniformly to prepare granular materials, and the composite pellets and the granular materials are distributed on a sintering machine layer by layer to be roasted to obtain chromium-containing sintered ore.

The chromium-containing waste residue is stainless steel pickling mud, the reducing agent is coke powder and anthracite, the binder is bentonite (the addition amount is about 1 percent of that of the pellet material), the iron ore in the granular material is a mixture of laterite-nickel ore and magnetite, and the flux is quicklime and dolomite.

In the composite pellet interlayer, the mass ratio of the carbon element of the coke powder to the oxygen element of the chromium slag is 0.5: 1.

The diameter of the inner sphere is 2mm, the diameter of the middle sphere is 6mm, and the diameter of the pellet is 11 mm.

The pelletizing time of the composite pellets is 12min, and the rotating speed of the pelletizing machine is 20 r/min.

The mass percentage composition of iron ore, flux and fuel in the granular material is 88.7%: 5.1%: 6.2 percent. Uniformly mixing iron ore, flux, fuel and water, and then performing roller granulation at the rotating speed of 23r/min for 5 min.

The particle size of the particle material comprises the following components: -3mm (43.6%), 3-5 mm (32.8%) +5mm (23.6%).

The green pellet compressive strength of the chromium slag composite pellet is 13.1N/pellet, the falling strength is 8.2 times/(0.5 m.pellet), and the bursting temperature is 580 ℃.

The mass ratio of the composite pellets to the granules is 40%: 60 percent.

The layered material distribution, namely the control of the proportion of the composite pellet material in the upper layer, the middle layer and the lower layer of the sintering machine is respectively 50%: 30%: 20 percent.

In example 2, the sintering rate was 27.62 mm/min^-1The yield was 73.88%, the drum strength was 58.56%, and the utilization factor was 1.503t (m)²·h)^-1. The hexavalent chromium content in the obtained sintering ore is 0.0003 percent (less than the national discharge standard of 0.0005 percent), and the one-step detoxification and resource utilization of the chromium slag are realized.

Example 3

The chromium-containing waste slag, a reducing agent and a binder are mixed uniformly to prepare chromium slag composite pellets, iron ore, a flux, coke powder and the like are mixed uniformly to prepare granular materials, and the composite pellets and the granular materials are distributed on a sintering machine layer by layer to be roasted to obtain chromium-containing sintered ore.

The chromium-containing waste slag is ferrochromium slag, the reducing agent is coke powder and anthracite, the binder is bentonite (the addition amount is about 1 percent of that of the pellet material), the iron ore in the granular material is magnetite, and the flux is quicklime.

In the composite pellet interlayer, the mass ratio of the carbon element of the coke powder to the oxygen element of the chromium slag is 0.4: 1.

The diameter of the inner sphere is 3mm, the diameter of the middle sphere is 7mm, and the diameter of the pellet is 12 mm.

The pelletizing time of the composite pellets is 12min, and the rotating speed of the pelletizing machine is 20 r/min.

The mass percentage composition of iron ore, flux and fuel in the granular material is 86.6%: 6.3%: 7.1 percent, evenly mixing the iron ore, the fusing agent, the fuel and the water, and then performing a roller granulator, wherein the rotating speed of a roller is 23r/min, and the granulation time is 5 min.

The particle size of the particle material comprises the following components: -3mm (27.3%), 3-5 mm (36.9%) +5mm (35.8%).

The green pellet compressive strength of the chromium slag composite pellet is 10.6N/pellet, the falling strength is 5.5 times/(0.5 m.pellet), and the bursting temperature is 450 ℃.

The mass ratio of the composite pellets to the granules is 20%: 80 percent.

The layered material distribution, namely the control of the proportion of the composite pellet material in the upper layer, the middle layer and the lower layer of the sintering machine is 55 percent respectively: 25%: 20 percent.

In example 3, the sintering rate was 18.38 mm/min^-1The yield was 78.02%, the drum strength was 69.32%, and the utilization factor was 1.384t (m)²·h)^-1. The hexavalent chromium content in the obtained sintering ore is 0.0001% (less than the national discharge standard of 0.0005%), thereby realizing one-step detoxification and resource utilization of the chromium slag.

Example 4

The chromium-containing waste slag, a reducing agent and a binder are mixed uniformly to prepare chromium slag composite pellets, iron ore, a flux, coke powder and the like are mixed uniformly to prepare granular materials, and the composite pellets and the granular materials are distributed on a sintering machine layer by layer to be roasted to obtain chromium-containing sintered ore.

The chromium-containing waste slag is a mixture of chromium salt slag and ferrochromium slag, the reducing agent is coke powder and anthracite, the binder is humic acid (the addition amount is about 1 percent of that of the pellet), the iron ore in the granular material is chromite, and the flux is quicklime.

In the composite pellet interlayer, the mass ratio of the carbon element of the coke powder to the oxygen element of the chromium slag is 0.5: 1.

The diameter of the inner sphere is 2mm, the diameter of the middle sphere is 6mm, and the diameter of the pellet is 9 mm.

The pelletizing time of the composite pellets is 12min, and the rotating speed of the pelletizing machine is 20 r/min.

The mass percentage composition of iron ore, flux and fuel in the granular material is 86.1%: 5.6%: 8.3 percent, evenly mixing the iron ore, the fusing agent, the fuel and the water, and then performing a roller granulator, wherein the rotating speed of a roller is 23r/min, and the granulation time is 5 min.

The particle size of the particle material comprises the following components: -3mm (31.5%), 3-5 mm (35.7%) +5mm (32.8%).

The green pellet compressive strength of the chromium slag composite pellet is 13.5N/pellet, the falling strength is 8.6 times/(0.5 m.pellet), and the bursting temperature is 600 ℃.

The mass ratio of the composite pellets to the granules is 50%: 50 percent.

The layered material distribution, namely the control of the proportion of the composite pellet material in the upper layer, the middle layer and the lower layer of the sintering machine is respectively 20%: 30%: 50 percent.

In example 4, the sintering rate was 25.11 mm/min^-1The yield was 73.22%, the drum strength was 62.47%, and the utilization factor was 1.401t (m)²·h)^-1. The hexavalent chromium content in the obtained sintering ore is 0.0002 percent (less than the national discharge standard of 0.0005 percent), and the one-step detoxification and resource utilization of the chromium slag are realized.

Example 5

The chromium-containing waste slag, a reducing agent and a binder are mixed uniformly to prepare chromium slag composite pellets, iron ore, a flux, coke powder and the like are mixed uniformly to prepare granular materials, and the composite pellets and the granular materials are distributed on a sintering machine layer by layer to be roasted to obtain chromium-containing sintered ore.

The chromium-containing waste residue is a mixture of chromium salt residue and ferrochromium residue, the reducing agent is coke powder and anthracite, the binder is humic acid (the addition amount is about 1 percent of that of the pellet), the iron ore in the granular material is a mixture of magnetite and hematite, and the flux is quicklime.

In the composite pellet interlayer, the mass ratio of the carbon element of the coke powder to the oxygen element of the chromium slag is 0.55: 1.

The diameter of the inner sphere is 2mm, the diameter of the middle sphere is 6mm, and the diameter of the pellet is 10 mm.

The pelletizing time of the composite pellets is 12min, and the rotating speed of the pelletizing machine is 20 r/min.

The mass percentage composition of iron ore, flux and fuel in the granular material is 88.3%: 3.8%: 7.9 percent, uniformly mixing the iron ore, the fusing agent, the fuel and the water, and then performing a roller granulator, wherein the rotating speed of a roller is 23r/min, and the granulation time is 5 min.

The particle size of the particle material comprises the following components: -3mm (28.6%), 3-5 mm (39.3%) +5mm (68.1%).

The green pellet compressive strength of the chromium slag composite pellet is 13.5N/pellet, the falling strength is 8.6 times/(0.5 m.pellet), and the bursting temperature is 600 ℃.

The mass ratio of the composite pellets to the granules is 40%: 60 percent.

The layered material distribution, namely the control of the proportion of the composite pellet material in the upper layer, the middle layer and the lower layer of the sintering machine is 34 percent respectively: 33%: 33 percent.

In example 5, the sintering rate was 19.89 mm/min^-1The yield was 75.03%, the drum strength was 65.87%, and the utilization factor was 1.412t (m)²·h)^-1. The hexavalent chromium content in the obtained sintering ore is 0.0001% (less than the national discharge standard of 0.0005%), thereby realizing one-step detoxification and resource utilization of the chromium slag.

Comparative example 1

The chromium salt slag, the anthracite and the binder are uniformly mixed and directly pelletized, the mass ratio of the carbon element of the coke powder to the oxygen element of the chromium slag is controlled to be 0.6:1, and the diameter of the pellet is 10 mm. And mixing chromite, flux, coke powder and the like uniformly to prepare granules, and then distributing the pellets and the granules on a sintering machine layer by layer for roasting to obtain chromium-containing sintered ore.

The chromium-containing waste slag is chromium salt slag, the reducing agent is coke powder and anthracite, the binder is bentonite (the addition amount is about 1 percent of that of the pellet), the iron ore in the granular material is chromite, and the flux is quicklime.

The pelletizing time of the composite pellets is 12min, and the rotating speed of the pelletizing machine is 20 r/min.

The mass percentage composition of iron ore, flux and fuel in the granular material is 88.6%: 4.7%: 6.6 percent, evenly mixing the iron ore, the fusing agent, the fuel and the water, and then performing a roller granulator, wherein the rotating speed of a roller is 23r/min, and the granulation time is 5 min.

The particle size of the particle material comprises the following components: -3mm (27.4%), 3-5 mm (33.7%) +5mm (61.3%).

The green pellet compressive strength of the chromium slag pellet is 12.5N/pellet, the falling strength is 6.9 times/(0.5 m.pellet), and the bursting temperature is 470 ℃.

The mass ratio of the composite pellets to the granules is 40%: 60 percent.

The layered material distribution, namely the control of the proportion of the composite pellet material in the upper layer, the middle layer and the lower layer of the sintering machine is respectively 50%: 30%: 20 percent.

The sintering speed of comparative example 1 was 23.05 mm/min^-1The yield was 71.08%, the drum strength was 60.62%, and the utilization factor was 1.305t (m)²·h)^-1. The hexavalent chromium content of the obtained sinter is 0.0008% (exceeding the national discharge standard of 0.0005%). The comparative example 1 mainly aims at the test comparison of whether the chromium slag pellets have a multilayer structure, and the chromium slag is not reduced thoroughly because the pellets are not wrapped by the anthracite cores and the outer layer.

Comparative example 2

Firstly, chromium salt slag, chromite, flux, coke powder and the like are mixed uniformly to prepare granular materials, and the granular materials are directly distributed on a sintering machine to be roasted to obtain chromium-containing sintered ore.

The mass percentage composition of iron ore, flux and fuel in the granular material is 89.0%: 3.3%: 7.3 percent, evenly mixing the iron ore, the fusing agent, the fuel and the water, and then performing a roller granulator, wherein the rotating speed of a roller is 23r/min, and the granulation time is 5 min.

The particle size of the particle material comprises the following components: -3mm (30.8%), 3-5 mm (35.6%) +5mm (33.9%).

The chromium-containing waste slag is chromium salt slag, the iron ore in the granular material is chromite, and the flux is quicklime.

The sintering speed of the comparative example 2 was 20.74 mm. min^-1The yield was 62.58%, the drum strength was 55.30%, and the utilization factor was 1.592t (m)²·h)^-1. The hexavalent chromium content in the obtained sintering ore is 0.1 percent (exceeding the national discharge standard of 0.0005 percent), and the one-step detoxification of the chromium slag cannot be realized. The comparative example 2 mainly aims at the comparison of the test that the chromium-containing waste residue is directly added and the granulated material is added after the pelletization, and the chromium residue is not completely reduced because the fuels are dispersed and distributed in the conventional sintering process and are mainly in an oxidizing atmosphere.

Comparative example 3

The chromium slag composite pellet is prepared by uniformly mixing electric furnace dust, a reducing agent and a binder, the mixture of magnetite and hematite, a flux, coke powder and the like are uniformly mixed to prepare a granular material, and the composite pellet and the granular material are distributed on a sintering machine in a layering manner to be roasted to obtain chromium-containing sintered ore.

The chromium-containing waste slag is electric furnace dust, the reducing agent is coke powder and anthracite, the binder is bentonite (the addition amount is about 1 percent of that of the pellet material), the iron ore in the granular material is a mixture of magnetite and hematite, and the flux is quicklime.

In the composite pellet interlayer, the mass ratio of the carbon element of the coke powder to the oxygen element of the chromium slag is 0.5: 1.

The diameter of the inner sphere is 2mm, the diameter of the middle sphere is 8mm, and the diameter of the pellet is 14 mm.

The pelletizing time of the composite pellets is 12min, and the rotating speed of the pelletizing machine is 20 r/min.

The mass percentage composition of iron ore, flux and fuel in the granular material is 88.4%: 5.6%: 6.0 percent, evenly mixing the iron ore, the fusing agent, the fuel and the water, and then performing a roller granulator, wherein the rotating speed of a roller is 23r/min, and the granulation time is 5 min.

The particle size of the particle material comprises the following components: -3mm (38.8%), 3-5 mm (36.5%) +5mm (24.7%).

The green pellet compressive strength of the chromium slag composite pellet is 14.3N/pellet, the falling strength is 5.2 times/(0.5 m.pellet), and the bursting temperature is 420 ℃.

The mass ratio of the composite pellets to the granules is 50%: 50 percent.

The layered material distribution, namely the control of the proportion of the composite pellet material in the upper layer, the middle layer and the lower layer of the sintering machine is respectively 50%: 30%: 20 percent.

Comparative example 3 the sintering rate was 20.39 mm. min^-1The yield was 72.02%, the drum strength was 63.05%, and the utilization factor was 1.530t (m)²·h)^-1. The hexavalent chromium content in the obtained sintering ore is 0.0008 percent (exceeding the national discharge standard of 0.0005 percent), and the one-step detoxification of the chromium slag cannot be realized. The comparative example 3 mainly aims at the experimental comparison of the sizes of the pellets, and the pellets are too large to be burnt through, so that the chromium slag is not reduced completely.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore intended that the present embodiments be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art will be able to make the description as a whole, and the embodiments in each example may be appropriately combined to form other embodiments that may be understood by those skilled in the art.