Method for co-processing waste incineration fly ash as admixture by cement kiln

Abstract

The invention discloses a method for co-processing waste incineration fly ash as an active admixture by a cement kiln. The method comprises the following steps: (1) oxidizing, curing and modifying; (2) granulation treatment; and (3) carrying out synergistic treatment to obtain the active admixture. The method is low in investment, low in treatment energy consumption, low in treatment cost, free ofsecondary pollution and easy to apply and popularize; heavy metals in the waste incineration fly ash are converted into an ionic state by using a modification treatment agent and are solidified and stabilized by using high-activity aluminosilicate groups; secondary pollution possibly caused by heavy metals, influence on a kiln system and influence on the cement hydration performance are prevented; all carbon-containing organic pollutants including dioxin are cleanly burnt out in a high-temperature alkaline dust oxidizing environment, heavy metals and alkali are fused through silicon-aluminumradical / silicate radical / aluminate radical lattices, chlorine and sulfur are converted into calcium chloro-aluminate and calcium sulfoaluminate minerals, which do not corrode reinforcing steel bars and have an early strength property, and energy saving and emission reduction are facilitated.

Description

technical field [0001] The invention relates to a method for disposing of waste incineration fly ash, in particular to a method for co-processing waste incineration fly ash in a cement kiln as an admixture. Background technique [0002] At present, as one of the environmental protection problems of domestic waste incineration power plants, "Yigu" waste incineration fly ash is the residue collected in the flue gas purification system, including dust collector fly ash and absorption tower fly ash or Scrubber sewage sludge, fly ash contains flue ash, added chemicals and chemical reaction products. The concentration of heavy metals Zn, Pb, Cu, Cr, Cd, Hg and other harmful substances in the incineration fly ash is high, especially when the current wet garbage is not well incinerated in the furnace, the reducing atmosphere in the furnace caused by incomplete combustion Part of the heavy metals are reduced and evaporated, and all the heavy metals whose evaporation point is lower t...

AI Technical Summary

Problems solved by technology

However, this method needs to continuously select landfills, and the construction and operation costs of safe landfills are not low. In addition, it is only safe and stable for a limited period of time, and the toxic and harmful organic substances in waste incineration fly ash and heavy metal ions and mercury have not been eliminated, and will eventually migrate out to pollute groundwater and soil

[0011] (2) Solidification landfill method: The currently implemented solidification landfill technology methods include cement solidification landfill, asphalt solidification landfill, landfill after melting and solidification, and landfill after chemical agent solidification. The heat treatment process of the melting and solidification landfill method Although it can digest organic pollutants such as dioxins, there are usually serious secondary pollution such as chlorinated acid flue gas and mercury volatilization and diffusion, etc. The investment and cost of treatment are extremely high, and the energy consumption is high. At the same time, it is also A waste of resources; among them, the cement solidification landfill, asphalt solidification landfill, landfill treatment method after chemical agent solidification, the toxic and harmful organic substances, heavy metal ions and mercury in the waste incineration fly ash have not been eliminated, especially for secondary Oxygens and dissolved salts have almost no stabilizing effect, and are still only a limited-term safe landfill disposal method that is invisible to the eye. In the end, toxic and harmful organic substances, heavy metal ions and mercury in the fly ash will still migrate out and pollute groundwater and soil.

Regardless of the fact that the enrichment degree of heavy metals in waste incineration fly ash is far from the economic level that other heavy metal-rich waste residues can be extracted, that is, regardless of the lack of economy at all, this type of heavy metal extraction method has serious waste water and waste residues. Secondary pollution, there are objectively the disadvantages of resource consumption and pollutant increment and expansion or diffusion

[0013] (4) Phosphoric acid washing method: leaching and washing waste incineration fly ash with phosphoric acid to reduce the leaching rate of heavy metals in fly ash, and the fly ash after phosphoric acid washing can be safely landfilled or used to make building materials or roadbed materials. Although it helps to improve the chemical stability of heavy metals in fly ash and the thermal stability of fly ash (forming phosphate precipitates), a large amount of organic matter and inorganic salts are still distributed in fly ash and phosphoric acid, and the limited phosphorus is wasted resource

[0014] (5) Manufacture of building material products such as building blocks: At present, the method of resource utilization of waste incineration fly ash to make building material products is to stabilize the waste incineration fly ash first, that is, to use pre-treatment processes such as washing and crushing to stabilize the fly ash Treatment, then, mixed with cement and aggregate to make cement concrete blocks or bricks, the existing method needs to solve the problem of secondary pollution caused by pretreatment, and the cement concrete blocks or bricks that are mixed with fly ash after pretreatment are incinerated The strength of the brick is low and the durability is poor. At the same time, due to the influence of excessive chloride ions, the Fe in the cement solidified block or brick 2+ 、Cu 2+ , Zn 2+ , Pb 2+ 、Cd 2+ Plasma is easy to leach, resulting in excessive pollutants

However, in this method, the heavy metals and toxic organic substances adsorbed in the fine particles are difficult to be effectively cleaned and removed, and certain organic pollutants such as heavy metals and dioxins are entrained in the kiln tail gas.

Second, it is difficult to wash sewage containing high salinity, heavy metals, and organic matter, and pollution is caused during the drying process (the water-washing membrane separation technology is similar to the "one-liquid" membrane separation concentrate that is extremely troublesome in waste-to-energy plants, objectively speaking Hazardous waste liquid) drying energy consumption is not low

Three high processing costs

This method will cause the chlorine in the fly ash to generate a large amount of chloric acid mist, which will not only cause loose corrosion of refractory materials, but also strengthen the crust of sulfur-alkali and hinder the solid fusion of alkali

Second, the chlorine in fly ash cannot effectively form calcium chloroaluminate minerals

In addition, heavy metals such as mercury in the fly ash that are easily reduced and volatilized migrate with the hot gas through the decomposition furnace and preheater, and finally escape in the humidifying tower and flue gas, causing pollution to spread

[0024] Apparently, the existing treatment methods for "Yigu" waste incineration fly ash are unsatisfactory, resulting in the fact that the fly ash of waste incineration power plants still has to adopt the "safe landfill method" when landfill sites are hard to find Disposal, resulting in land resource pollution