CN101293170A - A kind of composite material sulfur dioxide desulfurizer and preparation method thereof - Google Patents

Abstract

The invention discloses a composite material sulfur dioxide desulfurizer, which is characterized in that it contains the following components (all in mass percentage): 50-80% of white mud from an alkali plant, 10-40% of red mud from a steel plant, and 5.0-8.0% of a binder , 3.0% to 8.0% pore forming agent, 0.1 to 1.0% lubricant. Its preparation method is as follows: First, crush the white mud from the alkali factory and the red mud from the steel factory to a particle size larger than 40 mesh, mix it with the binder, pore-forming agent and lubricant according to the above ratio, then add water and mix it into a paste, and extrude it into a strip , drying, and finally high-temperature roasting to obtain the desulfurizer. The present invention is characterized in that the desulfurization agent is prepared by using industrial waste white mud and red mud. The desulfurization effect is good, the source is wide, the price is cheap, and there is no secondary pollution. The desulfurization product can also be used to build sea dams and roads. It can be widely used in the desulfurization and purification of flue gas from coal-fired power plants, coal-fired boilers and coal-fired kilns in the environmental protection industry.

Description

A kind of composite material sulfur dioxide desulfurizer and preparation method thereof

technical field

The present invention relates to a desulfurizer used in coal-fired power plants, coal-fired boilers, coal-fired kilns and other flue gas desulfurization industries and a preparation method thereof, more specifically to a preparation method using white mud from an alkali plant and red mud from a steel mill. _SO2 desulfurizer and preparation method thereof.

Background technique

According to reports, in 2005 China's total SO ₂ emission was as high as 25.5 million tons, ranking first in the world. Compared with 2000, it increased by 27%, and in 2006, it increased by 1.8% compared with 2005. China's atmospheric SO ₂ capacity index is 474 tons per year, which actually exceeded 4.6 times by 2006. A large amount of SO ₂ emission has caused increasingly serious environmental problems such as acid rain. On January 27, 2005, the State Environmental Protection Administration required 46 non-desulfurized thermal power plants in the acid rain control area and SO ₂ control area to rectify within a time limit. On February 17, 2005, an international agreement to curb global warming incorporated into laws and regulations - the "Kyoto Protocol" came into force, the Chinese government responded positively and set off an "environmental protection storm". However, how to effectively control SO ₂ has become an urgent and urgent problem to be solved in China's pollution control. According to statistics, 90% of China's total SO ₂ emissions come from coal-burning processes, among which the emissions from coal-fired power plants occupy the first place. Flue gas desulfurization (Flue Gas Desulfurization) is currently the world's main desulfurization method to control SO ₂ pollution and prevent acid rain hazards. Therefore, controlling SO ₂ emissions from coal-fired power plants is the top priority of flue gas desulfurization in China.

The methods of flue gas desulfurization can be divided into wet method and dry method according to the water content of absorbent and desulfurization product. Wet desulfurization technology is mature and has high desulfurization efficiency, but there are problems of post-treatment of wastewater, complex operation, huge equipment, high energy consumption, high cost, and low temperature of flue gas after washing, which is not conducive to purifying flue gas emissions. The dry desulfurization process is simple, low investment and operating costs, low energy consumption, no secondary pollution, high temperature of flue gas after purification, which is conducive to the diffusion of chimney exhaust. Although the desulfurization efficiency is slightly lower, it is sufficient to meet the requirements of environmental protection. Therefore, the research and development of dry flue gas desulfurization has attracted widespread attention at home and abroad in recent years. Dry desulfurization mainly includes furnace dry powder injection desulfurization method, high-energy electron activation oxidation method, charged dry powder injection desulfurization method, metal oxide desulfurization method and activated carbon or fly ash desulfurization method. Since there is no need for high-energy electronic generators, the trouble of solid waste treatment in charged dry powder injection desulfurization is reduced, and the adsorption performance and self-catalysis performance of activated carbon adsorption method are inherited. Metal oxide desulfurization has suddenly emerged in dry desulfurization. Attract people's attention. The removal method has also developed from a single metal oxide to a composite metal oxide, from general adsorption to catalytic adsorption or catalytic oxidation, with a rapid development momentum and unlimited prospects.

With the expansion of my country's steel production, the red mud by-products of steelmaking converters will increase day by day, and the emissions of various steelmaking industrial waste gases will also increase accordingly, which will inevitably put a certain pressure on the environment. In addition, the heat value of steelmaking waste gas is low, and the content of sulfur and other impurities (such as dust) is high, which is not suitable for long-distance transportation. However, combined cycle power generation after purification of waste gas is a good way for steelmaking enterprises to improve economic benefits and reduce environmental pollution. way. Red mud is waste slag produced during converter steelmaking, and its composition mainly contains Fe, Fe ₂ O ₃ , Fe ₃ O ₄ , FeO, CaCO ₃ and so on. Qingdao Soda Plant produces more than 180,000 tons (dry basis) of alkali-making waste residue and white mud every year, and its components mainly contain CaCO ₃ , Mg(OH) ₂ , CaSO ₄ , NaCl, CaCl ₂ , and metal oxides R ₂ O ₃ . Because the Cl ions contained in the lime mud have an impact on the production of wall coatings and other products, the market capacity of the products is limited, and the lime mud cannot be consumed in large quantities, so that it is impossible to find a good way to effectively control the lime mud. Both iron-based and calcium-based oxides have proven to be effective in flue gas desulfurization, so the use of "waste" white mud rich in calcium-based and magnesium-based oxides can be used to make high-efficiency and cheap flue gas desulfurization agents. However, due to the expansion of sodium chloride and calcium chloride in white mud, it will cause corrosion of equipment and other hazards. And the generated product _CaSO4 is easy to block the reaction channel, so that the desulfurization effect of the desulfurizer prepared by using white mud alone is not ideal. White mud seawater desulfurization effect is good, but the use temperature is low, resulting in the effective components of white mud Ca ²⁺ , Mg ²⁺ can not play a role in desulfurization, and there are difficulties in exhausting smoke, high energy consumption, secondary pollution, Cl ^- corrosion equipment, etc. shortcoming.

Contents of the invention

Aiming at the above-mentioned shortcoming of using lime mud desulfurization alone, the object of the present invention is to provide a kind of efficient, cheap, easy to prepare composite material _SO2 desulfurizer and its preparation method.

A composite material _SO2 desulfurizer prepared by utilizing white mud from an alkali plant and red mud from a steel mill, characterized in that it contains the following components (both in mass percentage): 50% to 80% white mud from an alkali plant, 10-40% red mud from a steel mill %, binder 5.0-8.0%, pore-forming agent 3.0%-8.0%, lubricant 0.1-1.0%.

Wherein the content of oxides of total iron in the red mud of the steel plant is greater than 50%, and the content of _CaCO3 in the white mud of the soda plant is greater than 50%;

The main components of the red mud of the steel plant are: Fe, Fe ₂ O ₃ , FeO, Fe ₃ O ₄ , CaCO _{3 ,} etc., and the main components of the white mud of the soda plant are: CaCO ₃ , Mg(OH) ₂ , CaSO ₄ , NaCl , CaCl ₂ , etc.;

The binder is kaolin, bentonite, white clay or diatomaceous earth;

The pore-forming agent is starch, semi-coke or polyacrylamide;

The lubricant is graphite.

The preparation method of the desulfurizer is as follows: first, crush the white mud of the alkali factory and the red mud of the steel factory to a particle size larger than 40 mesh, mix it with the binder, pore-forming agent and lubricant according to the above ratio, and then add water and mix it into a paste , extrusion, drying, and finally high-temperature roasting to obtain the desulfurizer. Wherein, the drying means drying in an oven at 100°C-110°C for 4-8 hours; high-temperature roasting refers to roasting in a muffle furnace at 350°C-650°C for 1-6 hours.

The activity and sulfur capacity tests of the desulfurizer were carried out in an atmospheric fixed-bed reactor. The reactor is a tubular stainless steel reactor with an inner diameter of 14 mm and a length of 320 mm. The desulfurizing agent is 4-10 mesh, the filling volume is 5ml desulfurizing agent, 20ml broken ceramic chips (for inert filler), the reactor bed height is 150mm, the _SO2 removal temperature is 350-600°C, and the space velocity is 300-1500h ^-1 , the particle diameter/pipe diameter ratio is 0.1-0.15, the flue gas composition is SO ₂ 1200-3000ppm, O ₂ 0-8%, H ₂ O 0-12%, and the rest is balanced by N ₂ . The sulfur capacity is the cumulative breakthrough sulfur capacity calculated when the desulfurization rate is greater than 80%.

Red mud itself also has a good flue gas desulfurization effect. For example, adding red mud containing a large amount of iron-based oxides to white mud to generate ferric chloride can fix chloride ions and form solid solutions with other substances, reducing Equipment corrosion. Oxide desulfurizers have high activity and good desulfurization effect at relatively high temperatures, which is just in line with the high outlet temperature of the boiler flue (200-1050°C). In this temperature range, no heating source is needed, and the desulfurizer already has Good desulfurization effect. The white mud and red mud are made into a molded desulfurizer to reduce the pressure drop, make the desulfurization effect better, save energy for the enterprise, and remove dust and heavy metals.

The present invention is characterized in that raw materials such as white mud, red mud and additives come from a wide range of sources, and the price is cheap. The prepared desulfurizer has good desulfurization effect and no secondary pollution. It can be widely used in coal-fired power plants, coal-fired boilers, coal-fired kilns and other flue gas desulfurization purification and environmental protection industries to treat waste with waste, so as to achieve a win-win situation for economy and environmental protection.

Detailed ways

The present invention will be described in detail below through specific examples.

The white mud and red mud used in the following examples come from Qingdao Soda Industry Group and Qingdao Iron and Steel Group respectively, and the specific components are shown in the following table:

Table 1 Soda plant lime mud composition (dry basis/%)

Element CaCO ₃ CaSO ₄ NaCl Mg(OH) ₂ SiO _{2 Fe2O3 _} Acid intolerant other content 53.21 2.69 7.01 13.43 9.09 6.89 3.66 -

Table 2 Composition of red mud in steel mills (dry basis/%)

Element α-Fe FeO _Fe3O4 CaCO ₃ Ca(OH) ₂ SiO ₂ and others content 10.5 25.6 27.0 17.8 3.0 16.1

Embodiment 1-4 and comparative example 1:

Mix different percentages of white mud and red mud, then mix with 5.0% bentonite, 4.9% starch and 0.1% graphite, add water and mix to form a paste, extrude, dry, and finally roast at high temperature , to prepare several desulfurizers. The white mud and red mud are both 40 mesh, dried at 105°C for 6 hours, roasted at 500°C, and roasted for 2 hours. The prepared desulfurizer was subjected to desulfurization activity evaluation test, and the results are shown in Table 3.

Table 3 Desulfurization effect of desulfurizers with different proportions (mass ratio)

Experimental conditions: temperature: 400°C; space velocity: 1200h ^-1 ; SO ₂ concentration: 6290mg/m ³ (2200ppm); O ₂ : ~5%; H ₂ O(g): 8%.

It can be seen from the table that when there is only white mud but no red mud, the sulfur capacity of the desulfurizer is the smallest, and the desulfurization effect is not good; while when the white mud:red mud=2:1, the sulfur capacity of the desulfurizer is the largest, and the breakthrough time The longest, the best desulfurization effect.

Embodiment 5-8 and comparative example 2:

Mix the white mud and red mud by 60% and 30% respectively, add 5.0% bentonite, 4.9% starch, and 0.1% graphite, mix it with water, mix it into a paste, extrude it, dry it, and finally pass it through high temperature Roasting treatment, prepare several desulfurizers according to the different meshes of white mud and red mud. Among them, drying at 105° C. for 6 hours, calcination temperature at 400° C., and calcination time of 2 hours. The mesh numbers of white mud and red mud are 16, 40, 60, 80, and 100 mesh respectively. The prepared desulfurizer was subjected to desulfurization activity evaluation test. The results are shown in Table 4.

Table 4 Desulfurization effects of desulfurizers prepared with different meshes

Experimental conditions: temperature: 400°C; space velocity: 1200h ^-1 ; SO ₂ concentration: 6290mg/m ³ (2200ppm); O ₂ : ~5%; H ₂ O(g): 8%

It can be seen from the table that as the mesh number of white mud and red mud increases, that is, the particle size becomes finer, the penetration time gradually prolongs, the sulfur capacity gradually increases, and the desulfurization effect is better.

Embodiment 9-12:

Mix white mud and red mud by 60% and 30% respectively, add 5% different binders, 4.9% starch as pore-forming agent, mix with 0.1% graphite, add water and mix into paste, extrude Shaping, drying, and finally high-temperature roasting to prepare several desulfurizers. The white mud and red mud are both 40 mesh, dried at 105°C for 6 hours, and roasted at 500°C for 2 hours. The binders are respectively kaolin, bentonite, white clay and diatomaceous earth. The prepared desulfurizer was subjected to desulfurization activity evaluation test. The results are shown in Table 5.

Table 5 Comparison of desulfurization effects of desulfurizers prepared by different binders

Experimental conditions: temperature: 400°C; space velocity: 1200h ^-1 ; SO ₂ concentration: 6290mg/m ³ (2200ppm); O ₂ : ~5%; H ₂ O(g): 8%

It can be seen from the table that the binder plays a great role in increasing the sulfur capacity of the desulfurizer, and the desulfurization effect is the best when kaolin is used as the binder.

Embodiment 13-14 and comparative example 3:

Mix white mud and red mud by 60% and 30% respectively, add 5.0% kaolin as binder, 4.9% different pore-forming agents, mix with 0.1% graphite, add water and mix into paste, extrude Shaping, drying, and finally high-temperature roasting to prepare several desulfurizers. The white mud and red mud are both 40 mesh, dried at 105°C for 6 hours, roasted at 500°C, and roasted for 2 hours. The prepared desulfurizer was subjected to desulfurization activity evaluation test. The results are shown in Table 6.

Table 6 Desulfurization effect of desulfurizer prepared by different pore-forming agents

Experimental conditions: temperature: 400°C; space velocity: 1200h ^-1 ; SO ₂ concentration: 6290mg/m ³ (2200ppm); O ₂ : ~5%; H ₂ O(g): 8%

It can be seen from the table that the highest desulfurization rate of desulfurizers with different pore-forming agents: starch > semi-coke > no pore-forming agent; desulfurization effect: starch > semi-coke > no pore-forming agent. Starch is used as a pore-forming agent, and the desulfurization effect is the best. For the desulfurizer without pore-forming agent, the desulfurization rate and sulfur capacity are both low.

Claims (9)

1. composite SO ₂Desulfurizing agent is characterized in that comprising following composition (all being mass percents): alkali factory white clay 50～80%, the red mud 10-40% of steel mill, binding agent 5.0～8.0%, pore creating material 3.0%～8.0%, lubricant 0.1～1.0%.

2. composite SO according to claim 1 ₂Desulfurizing agent, the oxide content that it is characterized in that in the described steel mill red mud total iron be greater than 50%, CaCO in the alkali factory white clay ₃Content is greater than 50%.

3. composite SO according to claim 1 and 2 ₂Desulfurizing agent is characterized in that described steel mill red mud main component is: Fe, Fe ₂O ₃, FeO, Fe ₃O ₄, CaCO ₃Main component is in the alkali factory white clay: CaCO ₃, Mg (OH) ₂, CaSO ₄, NaCl, CaCl ₂

4. composite SO according to claim 1 ₂Desulfurizing agent is characterized in that described binding agent is kaolin, bentonite, carclazyte or diatomite.

5. composite SO according to claim 1 ₂Desulfurizing agent is characterized in that described pore creating material is starch, semicoke or polyacrylamide.

6. composite SO according to claim 1 ₂Desulfurizing agent is characterized in that described lubricant is a graphite.

7. composite SO according to claim 1 ₂The preparation method of desulfurizing agent, it is characterized in that it comprises the steps: at first alkali factory white clay and steel mill's red mud powder to be broken to greater than 40 purpose granularities, mix in proportion with binding agent, pore creating material and lubricant, add water then and be mixed into pasty state, extruded moulding, oven dry are handled by high-temperature roasting at last and are promptly got desulfurizing agent.

8. composite SO according to claim 7 ₂The preparation method of desulfurizing agent is characterized in that wherein said oven dry is 100 ℃～110 ℃ dryings 4～8 hours in baking oven.

9. composite SO according to claim 7 ₂The preparation method of desulfurizing agent is characterized in that wherein said high-temperature roasting is meant in muffle furnace 350 ℃～650 ℃ roastings 1～6 hour.