Method for efficiently and synergistically recycling chromium-containing waste residues and carbon-containing waste materials
阅读说明：本技术 一种高效协同资源化利用含铬废渣和含碳废料的方法 (Method for efficiently and synergistically recycling chromium-containing waste residues and carbon-containing waste materials ) 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：本发明公开了一种高效协同资源化利用含铬废渣和含碳废料的方法,将包括含铬废渣与含碳废料在内的原料混匀造球,得到球形料；同时,将包括含铁原料、熔剂及燃料在内的原料混匀制粒,得到颗粒料；再将球形料与颗粒料混合后分层布料至烧结机上进行抽风烧结,即得含铬烧结矿。该方法在含铁原料烧结过程中高效协同资源化利用含铬废渣和含碳废料,不但可以一步实现含铬废渣的彻底解毒,而且可以资源化利用含铬废渣和含碳废料,为高炉冶炼含铬铁水提供优质炉料,具有明显的经济和环境效益。(The invention discloses a method for efficiently and synergistically utilizing chromium-containing waste residues and carbon-containing waste materials in a recycling manner, which comprises the steps of uniformly mixing raw materials including the chromium-containing waste residues and the carbon-containing waste materials for pelletizing to obtain a spherical material; meanwhile, uniformly mixing raw materials including an iron-containing raw material, a flux and a fuel, and granulating to obtain a granular material; and mixing the spherical material and the granular material, then distributing the mixture in layers to a sintering machine for air draft sintering to obtain the chromium-containing sintered ore. The method efficiently and synergistically utilizes the chromium-containing waste residues and the carbon-containing waste materials in a resource manner in the sintering process of the iron-containing raw materials, not only can realize the complete detoxification of the chromium-containing waste residues in one step, but also can utilize the chromium-containing waste residues and the carbon-containing waste materials in a resource manner, provides high-quality furnace charges for smelting chromium-containing molten iron in a blast furnace, and has obvious economic and environmental benefits.)
1. A method for efficiently and synergistically utilizing chromium-containing waste residues and carbon-containing waste materials is characterized by comprising the following steps: uniformly mixing raw materials including chromium-containing waste residues and carbon-containing waste materials for pelletizing to obtain a spherical material; meanwhile, uniformly mixing raw materials including an iron-containing raw material, a flux and a fuel, and granulating to obtain a granular material; and mixing the spherical material and the granular material, distributing the mixture to a sintering machine, and performing air draft sintering to obtain the chromium-containing sintered ore.
2. The method for efficiently and synergistically utilizing chromium-containing waste residues and carbon-containing waste materials as resources according to claim 1, which is characterized in that: the mass percentage composition of the chromium-containing waste residue and the carbon-containing waste material in the spherical material is (70-90%): (30-10%) and the fixed carbon content is not less than 6% by mass.
3. The method for efficiently and synergistically utilizing chromium-containing waste residues and carbon-containing waste materials as resources according to claim 1 or 2, which is characterized in that:
the chromium-containing waste residue comprises at least one of chromium salt residue, ferrochromium residue, chromium-containing electroplating sludge, stainless steel pickling sludge and electric furnace dust;
the carbon-containing waste comprises at least one of paint slag, waste plastics, municipal sludge and waste activated carbon.
4. The method for efficiently and synergistically utilizing chromium-containing waste residues and carbon-containing waste materials as resources according to claim 1, which is characterized in that: the particle size of the spherical material is 3-10 mm.
5. The method for efficiently and synergistically utilizing chromium-containing waste residues and carbon-containing waste materials as resources according to claim 1, which is characterized in that: the granular material comprises the following components in percentage by mass (82-95%): (2-8%): (3% to 10%).
6. The method for efficiently and synergistically utilizing chromium-containing waste residues and carbon-containing waste materials as resources according to claim 1, which is characterized in that: 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 3-5mm, the mass ratio is 20-40%, the particle size is more than 5mm, and the mass ratio is 10-60%.
7. The method for efficiently and synergistically utilizing chromium-containing waste residues and carbon-containing waste materials as resources according to claim 1 or 5, which is characterized in that: the iron-containing raw material comprises at least one of chromite, laterite-nickel ore, magnetite and hematite.
8. The method for efficiently and synergistically utilizing chromium-containing waste residues and carbon-containing waste materials as resources according to claim 1, which is characterized in that: the mass percentage composition of the spherical material and the granular material is (30-50%): (70% to 50%).
9. The method for efficiently and synergistically utilizing chromium-containing waste residues and carbon-containing waste materials as resources according to claim 1 or 8, which is characterized in that: the water content of the spherical material is 7-9% by mass; the water content of the granular material is 7-10% by mass.
10. The method for efficiently and synergistically utilizing chromium-containing waste residues and carbon-containing waste materials as resources according to claim 1 or 8, which is characterized in that: the layered cloth is divided into three layers, and the distribution mass proportion of the spherical material in the upper layer, the middle layer and the lower layer of the material layer is controlled to be (50-70%): (20-30%): (10% to 20%).
Technical Field
The invention relates to a resource utilization method of chromium-containing waste residues and carbon-containing waste materials, 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 a sintering method to realize one-step resource utilization of the chromium-containing waste residues and the carbon-containing waste materials in the 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 chromite yield, but the annual output of the chromite in China is less than 1% of the world annual output, the huge demand makes the chromium become one of the metals with the highest external dependence in China, and the contradiction between supply and demand is quite prominent.
On the other hand, the annual production of chromium-containing waste residues (chromium salt residues, chromium-containing electroplating sludge, stainless steel pickling sludge, electric furnace dust and the like) in China is nearly millions of tons, the accumulated stock exceeds 1000 million tons, and the chromium content in the chromium residues is high (3-7%). However, at present, a large amount of chromium in the chromium slag is not effectively utilized, and huge resource waste is caused. More seriously, the chromium-containing waste residue contains highly toxic hexavalent chromium, which causes corrosion and damage to organisms and carcinogenesis to human bodies, and is listed as dangerous solid waste by the nation, and the stockpiling of the waste residue causes huge environmental problems.
Therefore, the harmless treatment and resource utilization level of the chromium-containing waste residue is improved, the safety situation of chromium resources in China can be effectively improved, the threat of industrial toxic wastes to the natural environment can be eliminated, and the method has extremely important economic value and environmental benefit.
At present, the utilization approaches of the chromium-containing waste residue mainly comprise sintering ingredients, glass colorant, building material auxiliary materials and the like. In order to avoid the harm caused by the dissolution of hexavalent chromium, the use of the chromium-containing waste residue in the building material industry is extremely limited, and the chromium-containing colorant required by the glass industry is little, so that the chromium-containing waste residue is difficult to be largely consumed. The sintering-ironmaking method is a main way for disposing chromium-containing waste residues in part of enterprises at present, but production practices show that in the traditional sintering, when the addition amount of the chromium-containing waste residues exceeds 3%, the quality index of sintered ore products is obviously deteriorated, and part of chromium in the sintered ore still exists in the form of hexavalent chromium, so that potential secondary chromium pollution is caused. Therefore, the traditional sintering-ironmaking method cannot realize complete detoxification and resource utilization of the chromium-containing waste residue.
Numerous industries produce large quantities of carbon-containing waste materials such as paint slag, waste plastics, municipal sludge, waste activated carbon, etc., and the environmentally friendly and efficient disposal of these waste materials has been a hot topic. The automobile industry is a main source of paint slag, and according to incomplete statistics, the annual paint slag production of the automobile industry in China is 39 ten thousand tons. It is known that great wall motor companies treat paint slag at a cost of about 3000 yuan per ton. After the activated carbon is subjected to multiple adsorption reactions, the activity is reduced due to chemical changes and structural changes generated inside the activated carbon, the specific surface area is reduced, and the adsorption capacity cannot meet the production requirement and is formed into waste activated carbon. The treatment scheme of the waste activated carbon and paint slag is activation regeneration and incineration generally, but has the problems of long regeneration time, low regeneration efficiency, energy waste and the like. After crushing and grinding, the paint slag and the waste activated carbon are added into the sintering material to provide heat and reduce energy consumption, but because the surface activity is low, the direct addition deteriorates the granulation effect of the mixture and limits the addition amount.
In conclusion, the traditional sintering method can treat the chromium-containing waste residue and the carbon-containing waste material to a certain extent, but cannot realize the resource utilization of the chromium-containing waste residue and the carbon-containing waste material on a large scale.
Disclosure of Invention
Aiming at the defects of the prior method for detoxifying the chromium-containing waste residue and recycling the carbon-containing waste, the invention aims to provide a method for efficiently and synergistically recycling the chromium-containing waste residue and the carbon-containing waste.
The invention provides a method for efficiently and synergistically utilizing chromium-containing waste residues and carbon-containing waste materials in a resource manner, which comprises the steps of uniformly mixing raw materials including the chromium-containing waste residues and the carbon-containing waste materials for pelletizing to obtain spherical materials; meanwhile, uniformly mixing raw materials including an iron-containing raw material, a flux and a fuel, and granulating to obtain a granular material; and mixing the spherical material and the granular material, then distributing the mixture in layers to a sintering machine for air draft sintering to obtain the chromium-containing sintered ore.
The key point of the technical scheme of the invention is that chromium-containing waste residue and carbon-containing waste are prepared into spherical materials, other iron-containing raw materials, a flux, a fuel and the like are prepared into granular materials, the distribution proportion of the spherical materials and the granular materials in a sintering material layer is controlled, the spherical materials can be heated by fully utilizing the automatic heat storage of the sintering material layer and the thermal field of the granular materials in the sintering process, the spherical materials are rapidly heated, and meanwhile, the high-valence chromium compounds in the chromium-containing waste residue are directly reduced into metal chromium or chromium carbide under the high-temperature condition by utilizing the strong reduction action of fixed carbon in the carbon-containing waste material in the spherical materials, so that chromium-containing composite sintered ore is obtained and can be used for smelting chromium-containing molten iron.
As a preferable scheme, the mass percentage composition of the chromium-containing waste residue and the carbon-containing waste material in the spherical material is (70-90%): (30-10%) and the fixed carbon content is not less than 6% by mass. General carbon-containing waste materials generally have poor surface activity, and if the mixture ratio is too high, a large amount of binder needs to be added to ensure the strength of a spherical material; if the fixed carbon content is less than 6%, it is difficult to ensure complete reduction of chromium. Preferably, the mass ratio of the chromium-containing waste residue to the carbon-containing waste material in the spherical material is (70-80%): (30-20%) and the mass percentage content of the fixed carbon is more than or equal to 8%. The spherical material also contains a binder which is common in the industries such as bentonite and the like.
Preferably, the chromium-containing waste residue comprises at least one of chromium salt residue, ferrochromium residue, chromium-containing electroplating sludge, stainless steel pickling sludge and electric furnace dust. 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 mode, the carbon-containing waste material includes at least one of paint residue, waste plastic, municipal sludge, and waste activated carbon. The carbon-containing waste materials are common carbon-containing waste materials in the prior art, such as a high-molecular carbon source, a biomass carbon source, activated carbon and the like.
As a preferable scheme, the particle size of the spherical material is 3-10 mm. Preferably, the diameter of the spherical material is 6-8 mm.
As a preferable scheme, the mass percentage composition of the iron-containing raw material, the flux and the fuel in the granule material is (82% -95%): (2-8%): (3% to 10%). Preferably, the iron-containing raw material, the flux and the fuel in the granules are composed of (85-93%) by mass: (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 20-50%, the particle size is within the range of 3-5mm, the mass ratio is 20-40%, the particle size is more than 5mm, and the mass ratio is 10-60%. More preferably, the particle size composition of the granules is: the particle size is less than 3mm, the mass ratio is 25-45%, the particle size is within the range of 3-5mm, the mass ratio is 30-40%, the particle size is more than 5mm, and the mass ratio is 15-45%.
As a preferable scheme, the spherical material further comprises a binder, wherein the binder is a common additive for preparing the spherical material, such as bentonite and humic acid, and the addition proportion of the common additive is 0.8-4% of the mass of the spherical material.
As a preferred solution, the iron-containing raw material comprises at least one of chromite, laterite-nickel ore, magnetite, hematite.
As a preferable mode, the flux includes at least one of quicklime, dolomite, slaked lime, limestone and serpentine. These are fluxes conventionally used in the sintering of iron ores.
As a preferred scheme, the fuel comprises at least one of coke powder and anthracite.
As a preferable scheme, the total mass percentage of the spherical materials and the granular materials is (30-50%): (70% to 50%). If the adding proportion of the spherical materials is too small, the utilization amount of the chromium-containing waste residues is limited; if the addition proportion of the spherical materials is too large, the retention time of a high-temperature area is short when the sintering speed is too high, and a lot of minerals cannot be in time to form ores, so that the quality of the sintered minerals is poor, and the chromium-containing waste residue is not completely reduced. As further optimization, the total mass percentage of the spherical material and the granular 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 spherical material in the upper, middle and lower layers of the material layer is controlled to be (50-70%): (20-30%): (10% to 20%). Further preferably, the distribution mass proportion of the spherical materials in the upper, middle and lower layers of the material layer is (55-65%): (20-25%): (10% -20%), the proportion of the carbon-containing spherical materials in the middle and upper layers is improved, the automatic heat storage function in the sintering process is fully exerted, and the solid fuel consumption is reduced.
As a preferable scheme, the moisture content of the spherical material is 7-9% by mass. Further preferably, the water content of the spherical material is 8-9% by mass.
As a preferable scheme, the moisture content of the granular material is 7-10% by mass. The water content of the granular material is further preferably 8-8.5% by mass.
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, spherical materials made of the chromium-containing waste residues and the carbon-containing waste materials are reasonably matched with granular materials made of other iron-containing raw materials, fluxes and the like, the spherical materials are distributed into a sintering machine for air draft sintering, the spherical materials can be heated by fully utilizing the automatic heat storage of a sintering material layer and the thermal field of the granular materials in the sintering process, the temperature field of the spherical materials can be ensured to be higher than 1400 ℃, and simultaneously, the strong reduction action of fixing carbon in a high proportion of the carbon-containing waste materials in the spherical materials is utilized, the strong reduction atmosphere in the spherical materials can be ensured, 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 and synchronously realizing the resource utilization of the chromium-containing waste residues and the carbon-, the method provides high-quality furnace burden for blast furnace smelting of chromium-containing molten iron, provides a new way for clean, efficient and large-scale disposal and utilization of chromium-containing waste residues and carbon-containing waste materials, 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 carbon-containing waste comprises the following components in percentage by mass:
SiO20 to 4.97 wt%, MgO 0 to 0.75 wt%, TFe 0 to 0.91 wt%, Al2O30 to 19.25 wt%, CaO 0 to 17.24 wt%, and C17.34 to 96.15 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
Mixing chromium-containing waste residue, carbon-containing waste material and binder according to a certain mass ratio to form composite pellets, mixing iron ore, flux, fuel and the like to prepare granules, and then distributing the composite pellets and the granules on a sintering machine in a layering manner to perform air draft sintering to obtain chromium-containing sintered ore.
The chromium-containing waste residue is chromium salt residue, the carbon-containing waste material is paint residue and waste plastic, the binder is bentonite, the flux is quicklime, the iron ore is chromite, and the fuel is coke powder.
The composite pellet comprises 70% of chromium-containing waste residues and carbon-containing waste materials in percentage by mass: 30% with a fixed carbon content of 8.5%.
The diameter of the composite pellets is 6-8 mm.
The mass percentage composition of iron ore, flux and fuel in the granular material is (88.9%): (4.6%): (6.5%) the particle size range of the granules is: -3mm (24.6%), 3-5mm (31.9%) +5mm (43.5%).
The adding proportion of the spherical material binder is 2.4%.
The mass ratio of the composite pellets to the granules is 40%: 60 percent.
The moisture content of the composite pellets is 9 percent, and the moisture content of the granules is 8.5 percent.
The distribution mass proportion of the layered material, namely the spherical material in the upper, middle and lower layers of the material layer is controlled to be 60%: 25%: 15 percent.
In example 1, the sintering rate was 22.67 mm/min-1The yield was 74.77%, the drum strength was 65.73%, and the utilization factor was 1.606t (m)2·h)-1. The obtained sintering ore has the hexavalent chromium content of 0.0001 percent (less than the national discharge standard of 0.0005 percent), and realizes one-step detoxification of chromium slag and the cooperative resource utilization of chromium-containing waste slag and carbon-containing waste.
Example 2
Mixing chromium-containing waste residue, carbon-containing waste material and binder according to a certain mass ratio to form composite pellets, mixing iron ore, flux, fuel and the like to prepare granules, and then distributing the composite pellets and the granules on a sintering machine in a layering manner to be jointly roasted to obtain chromium-containing sintered ore.
The chromium-containing waste residue is ferrochromium residue and stainless steel acid washing mud, the carbon-containing waste material is waste activated carbon, the binder is humic acid, the iron ore is laterite-nickel ore and magnetite, the flux is quicklime and dolomite, and the fuel is coke powder.
The composite pellet comprises 80% of chromium-containing waste residues and carbon-containing waste materials in percentage by mass: 20% with a fixed carbon content of 9.6%.
The diameter of the composite pellet is 5-6 mm.
The iron ore, the flux and the fuel in the granular material consist of (89.1%) by mass: (5.1%): (5.8%) the particle size range of the granules is: -3mm (28.6%), 3-5mm (33.4%) +5mm (38.0%).
The adding proportion of the spherical material binder is 1.2%.
The mass ratio of the composite pellets to the granules is 45%: and 55 percent.
The moisture content of the composite pellets is 8%, and the moisture content of the granules is 8.5%.
The distribution mass proportion of the layered distribution, namely the distribution of the spherical materials in the upper, middle and lower layers of the material layer is controlled to be 65 percent: 25%: 10 percent.
In example 2, the sintering rate was 25.36 mm/min-1The yield was 70.71%, the drum strength was 56.80%, and the utilization factor was 1.568t (m)2·h)-1. The hexavalent chromium content in the obtained sintering ore is 0.0001 percent (less than the national discharge standard of 0.0005 percent), and the one-step detoxification of the chromium slag and the cooperative resource utilization of the chromium-containing waste slag and the carbon-containing waste material are realized.
Example 3
The chromium-containing waste slag, carbon-containing waste material and adhesive are uniformly mixed according to a certain mass ratio to produce composite pellets, the iron ore, flux and fuel are uniformly mixed to produce granules, then the composite pellets and granules are layered and distributed on a sintering machine to be co-roasted so as to obtain chromium-containing sintered ore, and the fuel is coke powder and anthracite.
The chromium-containing waste residues are chromium salt residues and ferrochrome residues, the carbon-containing waste materials are paint residues and municipal sludge, the binder is bentonite and humic acid, the iron ore is magnetite, and the flux is quicklime.
The composite pellet comprises 85% of chromium-containing waste residues and 85% of carbon-containing waste materials in percentage by mass: 15% with a fixed carbon content of 6.7%.
The diameter of the composite pellets is 6-8 mm.
The iron ore, the flux and the fuel in the granular material consist of (90.4%) by mass: (4.7%): (4.9%) the particle size range of the granules is: -3mm (25.8%), 3-5mm (35.9%) +5mm (38.3%).
The adding proportion of the spherical material binder is 3.1%.
The mass ratio of the composite pellets to the granules is 50%: 50 percent.
The moisture content of the composite pellets is 9 percent, and the moisture content of the granules is 8.5 percent.
The distribution mass proportion of the layered distribution, namely the distribution of the spherical materials in the upper, middle and lower layers of the material layer is controlled to be 65 percent: 20%: 15 percent.
In example 3, the sintering rate was 19.83 mm/min-1The yield was 74.62%, the drum strength was 62.95%, and the utilization factor was 1.260t (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 of the chromium slag and the synergistic resource utilization of the chromium-containing waste slag and the carbon-containing waste material are realized.
Example 4
Mixing chromium-containing waste residue, carbon-containing waste material and binder according to a certain mass ratio to form composite pellets, mixing iron ore, flux, fuel and the like to prepare granules, and then distributing the composite pellets and the granules on a sintering machine in a layering manner to be jointly roasted to obtain chromium-containing sintered ore.
The chromium-containing waste residue is a mixture of chromium salt residue and electric furnace dust, the carbon-containing waste material is waste activated carbon, the binder is bentonite, the iron ore is chromite, the flux is quicklime and serpentine, and the fuel is coke powder and anthracite.
The composite pellet comprises 90% of chromium-containing waste residues and 90% of carbon-containing waste materials in percentage by mass: 10% with a fixed carbon content of 6.1%.
The diameter of the composite pellets is 6-8 mm.
The mass percentage composition of iron ore, flux and fuel in the granular material is (88.9%): (5.3%): (5.8%) the particle size range of the granules is: -3mm (36.1%), 3-5mm (30.4%) +5mm (33.5%).
The adding proportion of the spherical material binder is 2.6%.
The mass ratio of the composite pellets to the granules is 30%: 70 percent.
The moisture content of the composite pellets is 7%, and the moisture content of the granules is 7%.
The distribution mass proportion of the layered material, namely the spherical material in the upper, middle and lower layers of the material layer is controlled to be 60%: 20%: 20 percent.
In example 4, the sintering rate was 23.38 mm/min-1To becomeThe yield was 73.91%, the drum strength was 61.94%, and the utilization factor was 1.259t (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 of the chromium slag and the synergistic resource utilization of the chromium-containing waste slag and the carbon-containing waste material are realized.
Example 5
Mixing chromium-containing waste residue, carbon-containing waste material and binder according to a certain mass ratio to form composite pellets, mixing iron ore, flux, fuel and the like to prepare granules, and then distributing the composite pellets and the granules on a sintering machine in a layering manner to be jointly roasted to obtain chromium-containing sintered ore.
The chromium-containing waste residue is ferrochrome residue, the carbon-containing waste material is a mixture of waste activated carbon and waste plastic, the binder is bentonite, the iron ore is a mixture of magnetite and hematite, and the flux is quicklime fuel, namely coke powder and anthracite.
The composite pellet comprises 75% of chromium-containing waste residues and 75% of carbon-containing waste materials in percentage by mass: 25% with a fixed carbon content of 8.6%.
The diameter of the composite pellet is 5-6 mm.
The mass percentage composition of iron ore, flux and fuel in the granular material is (88.9%): (5.3%): (6.7%) the particle size range of the granules is: -3mm (37.1%), 3-5mm (36.7%) +5mm (26.2%).
The adding proportion of the spherical material binder is 3.8%.
The mass ratio of the composite pellets to the granules is 35%: 65 percent.
The moisture content of the composite pellets is 8%, and the moisture content of the granules is 8.5%.
The distribution mass proportion of the layered distribution, namely the distribution of the spherical materials in the upper, middle and lower layers of the material layer is controlled to be 55%: 30%: 15 percent.
In this example 5, the sintering speed was 21.91 mm/min-1The yield was 74.27%, the drum strength was 66.00%, and the utilization factor was 1.497t (m)2·h)-1. The hexavalent chromium content in the obtained sintering ore is 0.0001 percent (less than the national discharge standard of 0.0005 percent), and the one-step detoxification of the chromium slag is realizedAnd the cooperative resource utilization of the chromium-containing waste residue and the carbon-containing waste.
Comparative example 1
Mixing chromium-containing waste residue, carbon-containing waste material and binder according to a certain mass ratio to form composite pellets, mixing iron ore, flux, fuel and the like to prepare granules, mixing the composite pellets and the granules, and then distributing the mixture to a sintering machine for combined roasting to obtain chromium-containing sintered ore.
The chromium-containing waste residue is chromium salt residue, the carbon-containing waste material is paint residue and active carbon, the binder is bentonite, the iron ore is laterite-nickel ore and magnetite, the flux is quicklime and dolomite, and the fuel is coke powder.
The composite pellet comprises 90% of chromium-containing waste residues and 90% of carbon-containing waste materials in percentage by mass: 10% with a fixed carbon content of 5.3%.
The diameter of the composite pellets is 6-8 mm.
The iron ore, the flux and the fuel in the granular material consist of (87.6 percent) by mass: (4.9%): (7.5%) the particle size range of the granules is: -3mm (33.6%), 3-5mm (34.3%) +5mm (32.1%).
The adding proportion of the spherical material binder is 3.4%.
The mass ratio of the composite pellets to the granules is 40%: 60 percent.
The moisture content of the composite pellets is 9 percent, and the moisture content of the granules is 8.5 percent.
The sintering speed of the comparative example 1 was 25.39 mm. min-1The yield was 70.17%, the drum strength was 56.83%, and the utilization factor was 1.636t (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-containing waste residue cannot be realized. This example 1 is mainly directed to the comparison of the fixed carbon content in the composite pellets with or without layered burden distribution. When the pellet material and the particle material are distributed without layering, the fuel consumption needs to be increased in order to ensure the quality of the sintered ore. When the fixed carbon content is less than 6%, the chromium reduction in the composite pellet is incomplete.
Comparative example 2
Mixing chromium-containing waste residue, carbon-containing waste material, iron ore, flux, fuel and the like uniformly to prepare granular materials, and then distributing the granular materials on a sintering machine for combined roasting to obtain chromium-containing sintered ore.
The chromium-containing waste residue is chromium salt residue and chromium-containing electroplating sludge, the carbon-containing waste material is paint residue and municipal sludge, the iron ore is chromite, and the fuel is coke powder.
The granular material comprises chromium-containing waste residues, carbon-containing waste materials, iron ore, a fusing agent and fuel in percentage by mass (21.5%): (8.7%): (64.3%): (2.8%): (2.7%) the particle size range of the granules is: -3mm (27.6%), 3-5mm (38.1%) +5mm (34.3%).
The moisture content of the granular material is 8.5%.
The sintering speed of the comparative example 2 was 21.83 mm. min-1The yield was 72.62%, the drum strength was 60.35%, and the utilization factor was 1.460t (m)2·h)-1. The hexavalent chromium content in the obtained sintering ore is 0.12 percent (exceeding the national discharge standard of 0.0005 percent), and the one-step detoxification of the chromium-containing waste residue cannot be realized. This example 2 is mainly directed to comparison of the presence or absence of composite pellets prepared. Because the sintering process is mainly in an oxidizing atmosphere, when chromium-containing waste residues and carbon-containing waste materials are directly added to prepare granules, the chromium residues and the carbon-containing components are not fully contacted, so that the hexavalent chromium is not completely reduced.
Comparative example 3
Mixing chromium-containing waste residue, carbon-containing waste material and binder according to a certain mass ratio to form composite pellets, mixing iron ore, flux, fuel and the like to prepare granules, and then distributing the composite pellets and the granules on a sintering machine in a layering manner to be jointly roasted to obtain chromium-containing sintered ore.
The chromium-containing waste residue is stainless steel pickling mud, the carbon-containing waste material is waste activated carbon and municipal sludge, the binder is bentonite, the iron ore is magnetite and hematite, the flux is quicklime and serpentine, and the fuel is coke powder.
The composite pellet comprises 85% of chromium-containing waste residues and 85% of carbon-containing waste materials in percentage by mass: 15% with a fixed carbon content of 7.3%.
The diameter of the composite pellets is 9-10 mm.
The iron ore, the flux and the fuel in the granular material consist of (87.6 percent) by mass: (4.3%): (5.1%) the particle size range of the granules is: -3mm (16.4%), 3-5mm (27.3%) +5mm (43.7%).
The adding proportion of the spherical material binder is 2.9%.
The mass ratio of the composite pellets to the granules is 55%: 45 percent.
The moisture content of the composite pellets is 7.5%, and the moisture content of the granules is 9%.
The distribution mass proportion of the layered distribution, namely the distribution of the spherical materials in the upper, middle and lower layers of the material layer is controlled to be 55%: 25%: 20 percent.
Comparative example 3 the sintering speed was 28.92 mm/min-1The yield was 60.35%, the drum strength was 52.58%, and the utilization factor was 1.763t (m)2·h)-1. The quality index of the sintered ore is not good, the hexavalent chromium content in the obtained sintered ore is 0.1 percent (exceeds the national discharge standard of 0.0005 percent), and the one-step detoxification of the chromium-containing waste residue cannot be realized. This example 3 is directed primarily to a comparison of the particle size distribution of the particulate material. As the proportion of particles with the diameter of-3 mm and the diameter of 3-5mm in the particle material is too small, the sintering speed is too high, and the hexavalent chromium is not completely reduced.
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.