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CN-118458790-B - Method for preparing porous hydrated calcium silicate by using high-silicon gas slag

CN118458790BCN 118458790 BCN118458790 BCN 118458790BCN-118458790-B

Abstract

The invention provides a method for preparing porous hydrated calcium silicate by using high-silicon gas slag, which comprises the following steps of 1) screening to obtain high-silicon gas slag, 2) preparing coarse slurry according to the contents of SiO 2 and Al 2 O 3 in the gas slag, 3) grinding the coarse slurry to obtain fine slurry, 4) roasting the ground fine slurry at high temperature to obtain blocky clinker, 5) grinding the blocky clinker to obtain powdery clinker, 6) mixing the powdery clinker with lime milk to obtain slurry, 7) filtering, dehydrating, washing and drying the slurry to obtain a product, 8) mixing the washing liquid and filtrate of the step 7) and then evaporating and concentrating the mixture, and recycling the concentrated liquid for preparing the gas slag slurry. The invention not only realizes the high-value utilization of the whole components of the gas slag, but also has no secondary discharge of three wastes. The process is simple, the flow is short, no special requirement is made on equipment, the cost is low, the application range of the product is wide, the added value is high, and meanwhile, the NaOH alkali liquor can be recycled.

Inventors

  • YANG ZHIJIE

Assignees

  • 内蒙古工业大学

Dates

Publication Date
20260508
Application Date
20240402

Claims (10)

  1. 1. The method for preparing the porous hydrated calcium silicate by using the high-silicon gas slag is characterized by comprising the following steps of: 1) The method comprises the steps of respectively detecting the moisture content and the chemical component content of dry basis of the gas slag, and screening to obtain high-silicon gas slag, wherein the moisture mass percent of the high-silicon gas slag is less than or equal to 38%, and the SiO 2 mass percent of the dry basis of the high-silicon gas slag is more than or equal to 40%; 2) Adding NaOH solution according to the contents of SiO 2 and Al 2 O 3 in dry chemical components of the gas slag, so that the molar ratio of Na/(Si+Al) is 1.5-2.2, and preparing coarse slurry; 3) Grinding the prepared coarse slurry by wet grinding to obtain fine slurry; 4) Roasting the ground fine slurry by using a wet rotary kiln, and cooling to obtain blocky clinker; 5) Grinding the blocky clinker to obtain powdery clinker; 6) Mixing the powdery clinker and lime milk according to the mol ratio of CaO/SiO 2 of 0.90-1.10 to obtain slurry; 7) Filtering and dehydrating the slurry obtained in the step 6), and washing the dehydrated porous calcium silicate mineral; 8) The washing solution of the step 7) is evaporated and concentrated after being mixed with the filtrate, and the concentrated solution is recycled to be used for preparing the slurry of the coal gasification slag in the step 2); 9) And drying the filtered and washed porous hydrated calcium silicate material to obtain the porous hydrated calcium silicate.
  2. 2. The method for preparing porous calcium silicate hydrate by using high-silicon gas slag according to claim 1, wherein in the step 1), the mass percentage of Al 2 O 3 and the mass percentage of CaO in the dry basis of the high-silicon gas slag are less than or equal to 15 percent.
  3. 3. The method for preparing porous calcium silicate hydrate by utilizing high-silicon gas slag according to claim 1, wherein in the step 2), the concentration of NaOH solution is 4.5-5.5 mol/L.
  4. 4. The method for producing porous calcium silicate hydrate using high silicon gas slag according to claim 1, wherein in step 3), the maximum particle size of the solid particles in the fine slurry is 0.045 μm or less.
  5. 5. The method for preparing porous hydrated calcium silicate by using high-silicon gas slag according to claim 1, wherein in the step 4), the roasting temperature is 760-810 ℃ and the roasting time is 15-30 min.
  6. 6. The method for preparing porous calcium silicate hydrate by using high silicon gas slag according to claim 1, wherein in the step 5), the maximum particle size of the powder clinker is less than or equal to 0.045 μm.
  7. 7. The method for preparing porous hydrated calcium silicate by using high-silicon gas slag according to claim 1, wherein in the step 6), after the slurry is obtained, the slurry is heated at 75-100 ℃ for 45-80 min while stirring at a speed of 40-80 r/min.
  8. 8. The method for preparing porous hydrated calcium silicate by using high-silicon gas slag according to claim 1, wherein in step 6), caO effective and effective of the lime milk is more than 150g/L, and whiteness is more than or equal to 75%.
  9. 9. The method for preparing porous hydrated calcium silicate by using high-silicon gas slag according to claim 1, wherein in the step 8), the concentrated solution is circulated to prepare the slurry of the coal gasification slag in the step 2) until the concentration of NaOH reaches 4.5-5.5 mol/L.
  10. 10. A porous calcium silicate hydrate prepared by the method of any one of claims 1 to 9.

Description

Method for preparing porous hydrated calcium silicate by using high-silicon gas slag Technical Field The invention relates to a method for preparing porous hydrated calcium silicate by using high-silicon gas slag, belonging to the field of chemical industry and material interdisciplinary disciplines. Background Although coal is used as a main energy source for a long time, a clean and efficient utilization way of coal is required. Under such a background, the coal chemical industry of coal-to-liquid, methanol, olefin, ethylene glycol and the like is rapidly developing, and chemical coal discharges a large amount of gas slag (including coarse slag and fine slag). As a new type of solid waste composed of unburned carbon and inorganic components, how to treat and utilize the gas slag has become a problem to be solved. At present, the gas slag is mainly piled up, and the utilization aspect is still in the research and development stage. The development direction is mainly focused on that unburned carbon is used as an adsorbent or a chemical filler after decarbonizing gas slag, and inorganic components are mainly used as building materials. However, because the components and structures of unburned carbon in the coal gasification slag are greatly different from those of conventional coal, the traditional coal preparation process technology is difficult to realize efficient separation of unburned carbon and inorganic components in the coal gasification slag, so that large-scale application is difficult to realize. Meanwhile, the moisture content in the gas slag is up to more than 40%, and the drying cost in the utilization process is high, so that the utilization of the gas slag needs to go a high-value utilization route. The research on the high-value utilization of the gas slag mainly comprises the steps of leaching inorganic components in the gas slag by an acid method, and then utilizing the leaching liquid to synthesize zeolite or flocculant. The technology mainly has the problems that unburned carbon needs to be removed through filtration after leaching by an acid method, but because the particle size of part of unburned carbon is very small, the solid-liquid separation is difficult to realize through filtration, the used acid liquor is easy to volatilize, the working environment is bad, and the corrosion resistance requirement on equipment is extremely high, so that the unburned carbon is difficult to go out of a laboratory, and the industrial application is realized. Disclosure of Invention The invention aims to carry out high-value utilization on coal gasification slag with high silicon content, and provides a method for preparing porous hydrated calcium silicate by utilizing high-silicon coal gasification slag, which comprises the following steps: 1) The method comprises the steps of respectively detecting the moisture content and the chemical component content of dry basis of the gas slag, and screening to obtain high-silicon gas slag, wherein the moisture mass percent of the high-silicon gas slag is less than or equal to 38%, and the SiO 2 mass percent of the dry basis of the high-silicon gas slag is more than or equal to 40%; The gas slag dry base is a product obtained by drying the gas slag. The dry chemical components of the gas slag mainly comprise SiO 2、CaO、Al2O3、Fe2O3、Na2 O, mgO and loss on ignition, and the main mineral components are amorphous minerals and a small amount of zeolite. The loss on ignition is the unburned carbon in the dry base of the gas slag. The invention limits the water content of the high silicon gas slag to be less than or equal to 38 percent. If the water content in the gas slag is too high, the prepared coarse slurry and fine slurry have lower solid phase content. This results in a lower yield of clinker on post-firing, but also in a higher energy consumption. Production tests show that the energy consumption in the roasting stage is increased by about 4.8% for every 1% increase in the liquid phase content of the fine slurry. Furthermore, in the gas slag used in the invention, the mass percentage of SiO 2 is more than 40%. The reason is that the target product of the invention is porous calcium silicate hydrate, and the main components of the gas slag are mainly Al 2O3 and CaO except SiO 2. If the content of Al 2O3 and CaO is too high, a large amount of NaAlO 2 and beta-2 CaO.SiO 2 are generated in the roasting stage, and when the porous calcium silicate is synthesized by lime milk, a large amount of NaAlO 2 cannot participate in the synthesis of the porous calcium silicate hydrate in the form of AlO 4, but is precipitated in the solid phase of Al (OH) 3, so that the quality of the porous calcium silicate hydrate is affected. Beta-2 CaO.SiO 2 is a mineral with slower hydration rate, if the amount of beta-2 CaO.SiO 2 in clinker is small, the mineral can be fully hydrated to form porous hydrated calcium silicate, and if the amount of beta-2 CaO.SiO 2 is large, the syntheti