1. A method for preparing cement raw material balls by desalting waste incineration fly ash is characterized in that the waste incineration fly ash is used as a siliceous raw material of Portland cement clinker, then is mixed with a calcareous raw material and iron powder, and is consolidated into clusters through a hydraulic cementing material, soaked for desalting, and finally salt-free cement raw material balls are prepared; wherein, on the premise that the mass ratio of the fly ash is 20-30% and the mass ratio of the hydraulic cementing material is 10-15%, the dosage of the calcareous raw materials and the dosage of the iron powder are determined according to three major values prepared by cement raw materials.

2. The method for preparing cement raw material pellets by desalting waste incineration fly ash according to claim 1, wherein the hydraulic binder is one or more of portland cement, alkali-activated slag, geopolymer, sulphoaluminate cement, and magnesium phosphate cement.

3. The method for preparing the cement raw material ball by desalting the waste incineration fly ash according to claim 1, wherein the calcareous raw material is one or more of limestone, chalk or battery mud.

4. The method for preparing the cement raw material pellets by desalting the waste incineration fly ash according to claim 1, wherein the waste incineration fly ash is fly ash and bottom ash settled at the bottom of a flue and a chimney and a flue gas purification system of a household garbage incineration power plant.

5. The method for preparing cement raw material balls by desalting waste incineration fly ash according to claim 1, which is characterized by comprising the following steps:

step 1, determining the chemical composition of the used raw materials, and determining the dosage of the calcareous raw materials and the dosage of iron powder according to three major values prepared by cement raw materials on the premise that the mass ratio of fly ash is 20-30% and the mass ratio of hydraulic cementing materials is 10-15%;

step 2, mixing the components, adding water and a water reducing agent into the mixture at normal temperature, and stirring to obtain a dry and thick paste, wherein the accurate dosage of the water and the water reducing agent is based on convenient granulation;

step 3, pouring the paste into a granulator to prepare spherical particles with the particle size of 5-20mm until the surfaces of the particles are smooth and have no cracks and the particles are not adhered to each other, thus obtaining the spherical particles to be desalted;

step 4, standing the spherical particles to be desalted until the spherical particles are fully solidified, wherein the standard of full solidification is based on that the spherical particles are not dispersed or argillized after being soaked in water;

and 5, pouring the fully solidified particles into a clean water tank to be soaked for 0.5-1 hour, controlling the solid-to-liquid ratio of soaking to be 1:4-7, and ensuring that salt in the particles is fully leached to obtain the fly ash-based desalted cement raw material balls.

6. Use of a method for producing cement clinker based on cement green pellets according to claim 1.

Background

According to the statistical result of the national statistical bureau, the clear volume of domestic garbage in 2018 is 22802 ten thousand tons, more than 60% of large and medium cities in 600 cities in the country are surrounded by garbage, and 1/4 cities suffer from 'garbage enclosing city'. At present, the best treatment method for large-volume domestic garbage is garbage incineration, combustible carcinogens, viral pollutants and highly toxic organic matters in the garbage can be removed through incineration, and the garbage can be incinerated to generate power due to high combustion heat.

The accumulation of a large amount of municipal solid waste occupies land resources, causing serious environmental pollution. The combustion and power generation by using the municipal solid waste are the main means of reduction treatment, and 20 percent of fly ash and 80 percent of slag are generated by burning the waste. The fly ash contains high-concentration heavy metals such as Pb, Cd, Hg, Zn, Cu and the like, and high-toxicity organic pollutants such as dioxin, furan and the like, and is determined as strictly-controlled hazardous waste in China and is strictly prohibited to use.

However, in the process of waste incineration, volatile heavy metals, dioxin and the like are easily enriched on the surfaces of fly ash particles, so that the fly ash contains high leaching toxicity of the heavy metals and dioxin pollutants, which are classified as hazardous wastes by national hazardous waste records, United States Environmental Protection Agency (USEPA), Japan and European Union standards in China, and can enter into the ecological environment only after being specially treated.

Many studies have been made on the solidification treatment of heavy metals in fly ash, including cement solidification, asphalt solidification, chemical stabilization, sintering, melting, geopolymer solidification, and the like. As the fly ash contains CaO and SiO₂And Al₂O₃Similar to the components of cement raw materials, the calcium-silicon-aluminum-calcium-magnesium-calcium. But the best treatment method with the most industrialized application prospect at present adopts cement kiln for cooperative treatment.

However, after the refuse incineration fly ash was subjected to a fluorescence analysis test, it was found that the fly ash contained 20% or more of chlorine element. When the waste incineration fly ash is used for firing cement clinker, under the high-temperature calcination condition of 1400 ℃ to 1500 ℃ in a cement kiln, the chlorine-containing fly ash in a molten state can infiltrate through gaps of refractory bricks and contact with a metal structure of a kiln body shell to destroy the kiln body structure. In addition, alkali metals, chlorine and other elements in the fly ash are circularly enriched in the cement kiln, and are cooled and fused in a kiln tail predecomposition system to cause skinning, so that the normal production of the kiln and the quality of cement products are influenced slightly, and the kiln is closed seriously. Meanwhile, elements such as chlorine and alkali metal in the waste incineration fly ash can cause harm to the ecological cement clinker.

In order to solve the problem of over-high chlorine in the fly ash, a water washing method is generally adopted to remove chlorine salt in the fly ash. However, practice proves that the fly ash belongs to superfine powder, so that a large amount of water can be adsorbed from the air, a hydroxyl base layer and multiple layers of physical adsorption water are formed on the surface of the fly ash, if the fly ash is treated by adopting a conventional powder washing method, powder and liquid in slurry are mixed and difficult to separate after water washing, even if a filter pressing dehydration method is adopted, more than 40% of water is difficult to remove, and the separated liquid is turbid, so that the subsequent filter liquor is difficult to perform innocent treatment, and the subsequent purification treatment cost is high. The water content of the washed fly ash is high, the energy consumption of drying treatment is large, the cost is greatly increased, and the development of resource application of the fly ash is greatly limited.

CN106734045A discloses a method for treating fly ash from domestic waste incineration by a wet-process mold bag, which fully and simultaneously realizes fly ash homogenization, heavy metal and dioxin detoxification, desalination and spontaneous hydration consolidation forming by 3 links of fly ash pulping, fly ash slurry conveying and fly ash slurry dehydration/hydration consolidation; the fly ash in the solidified die bag body meets the requirements of relevant national standards, the solidified die bag body can be subjected to landfill treatment, and the fly ash can be taken out from the die bag for resource utilization; and (3) naturally evaporating and concentrating the liquid discharged from the mold bag by utilizing the space of a landfill, and recycling the liquid after recovering heavy metals and dioxin, filtering and removing impurities, or further extracting salt and recycling the liquid. The invention also discloses a system for treating the household garbage incineration fly ash by the mould bag method. The method can avoid the defects of the traditional dry landfill of the fly ash and the large-scale industrial application of the water washing pretreatment technology, can realize the integrated treatment of the homogenization, detoxification, desalination, spontaneous hydration consolidation and landfill of the fly ash, lays a foundation for the subsequent resource utilization of the fly ash, has low treatment cost, and can be applied to large-scale industrial production. However, as can be seen from analysis, the patent has serious technical problems, such as "fly ash: water =1:2-20 ", the water consumption is amazing, there is no commercial transformation value," the modified mould bag is rested for 2-20 days after filling with the fly ash slurry ", the disposal time is too long, the actual production can't be operated, the inefficiency, there is no commercial transformation value; the water content of the fly ash is good, even if the water content of the fly ash is still higher than 30% through powerful filter pressing, the technology adopts the natural percolation of the mold bags, the water content of the fly ash can be higher than 60%, salt is still dissolved in contained water, the desalting effect is limited, the filtered water is turbid, the water consumption is large, and the purification cost is high; fly ash like mud never solidifies by itself even if there is little spontaneous hydration reaction for a long time, and even if 20% of cement is added, the water consumption is so large that it will not solidify. The landfill can not be carried out without curing treatment, so that the patent is not enough to influence the application of subsequent patents.

CN111515225A discloses a method for treating fly ash from waste incineration, which comprises the following steps: (1) washing the fly ash by using a washing liquid, and performing solid-liquid separation to obtain a washing residual liquid and desalted fly ash; (2) mixing a chelating agent, a stabilizer and the desalted fly ash obtained in the step (1), and carrying out heavy metal stabilization treatment to obtain heavy metal stabilized fly ash; (3) and (3) mixing cement with the heavy metal stable fly ash obtained in the step (2), curing and packaging, bagging and sealing to finish the fly ash treatment. Firstly, desalting the fly ash to reduce the fly ash; and the removal of the dissolved salt is beneficial to the stability after solidification and wrapping, and the risk of re-precipitation of heavy metal ions caused by long-time landfill of the fly ash is reduced, so that the fly ash is effectively treated. Although the present invention is effective, the present invention is not disclosed sufficiently, and in the "first step: the fly ash is washed by water, the solid-liquid ratio is 1 (1-10), the stirring time is 5-30min, the standing time is 30-60min, the efficiency is too low, the most critical is the solid-liquid separation, but the disclosure is not provided. In addition, this patent does not disclose water washing for desalination, and has a great problem in practical application.

Disclosure of Invention

Aiming at the problems of cement clinker fired by the existing washing fly ash, the invention provides a method for preparing cement raw material balls by desalting waste incineration fly ash and application thereof. The method mixes the waste incineration fly ash used as siliceous raw material of portland cement clinker with other materials required by cement raw meal, concretes the mixture into clusters through hydraulic cementing materials, soaks the clusters for desalination, and prepares the salt-free cement raw meal balls.

A method for preparing cement raw material balls based on waste incineration fly ash desalination is characterized in that waste incineration fly ash is used as a siliceous raw material of portland cement clinker, then the siliceous raw material is mixed with a calcareous raw material and iron powder, and the mixture is consolidated into a mass through a hydraulic cementing material, soaked and desalinated to finally prepare salt-free cement raw material balls; wherein, on the premise that the mass ratio of the fly ash is 20-30% and the mass ratio of the hydraulic cementing material is 10-15%, the dosage of the calcareous raw materials and the dosage of the iron powder are determined according to three major values prepared by cement raw materials.

The improvement is that the hydraulic cementing material is one or more of silicate series cement, alkali activated slag, geopolymer, sulphoaluminate cement or magnesium phosphate cement.

The improvement is that the calcareous material is one or more of limestone, chalk or battery mud.

The improvement is that the waste incineration fly ash is the fly ash and bottom ash settled at the bottom of the flue and chimney and the collected matters of the flue gas purification system of the household waste incineration power plant.

The improvement comprises the following specific steps:

step 1, determining the chemical composition of the used raw materials, and determining the dosage of the calcareous raw materials and the dosage of iron powder according to three major values prepared by cement raw materials on the premise that the mass ratio of fly ash is 20-30% and the mass ratio of hydraulic cementing materials is 10-15%;

step 2, mixing the components, adding water and a water reducing agent into the mixture at normal temperature, and stirring to obtain a dry and thick paste, wherein the accurate dosage of the water and the water reducing agent is based on convenient granulation;

step 3, pouring the paste into a granulator to prepare spherical particles with the particle size of 5-20mm until the surfaces of the particles are smooth and have no cracks and the particles are not adhered to each other, thus obtaining the spherical particles to be desalted;

step 4, standing the spherical particles to be desalted until the spherical particles are fully solidified, wherein the standard of full solidification is based on that the spherical particles are not dispersed or argillized after being soaked in water;

and 5, pouring the fully solidified particles into a clean water tank to be soaked for 0.5-1 hour, controlling the solid-to-liquid ratio of soaking to be 1:4-7, and ensuring that salt in the particles is fully leached to obtain the fly ash-based desalted cement raw material balls.

Has the advantages that:

compared with the prior art, the method for preparing the cement raw material balls based on waste incineration fly ash desalination and the application thereof have the following advantages:

(1) the desalination is sufficient, and the problems that the chlorine salt damages the kiln body and influences the clinker firing quality are solved

The waste incineration fly ash contains more than 20 percent of chlorine element, and when the waste incineration fly ash is used for firing cement clinker, under the high-temperature calcination condition of 1400 ℃ and 1500 ℃ in a cement kiln, the molten chlorine-containing fly ash can infiltrate through gaps of refractory bricks and contact with a metal structure of a kiln body shell to destroy the kiln body structure. In addition, alkali metals, chlorine and other elements in the fly ash are circularly enriched in the cement kiln, and are cooled and fused in a kiln tail predecomposition system to cause skinning, so that the normal production of the kiln and the quality of cement products are influenced if the elements are light, and the kiln is closed if the elements are heavy; meanwhile, elements such as chlorine and alkali metal in the waste incineration fly ash can cause harm to the ecological cement clinker. The method can fully remove soluble chloride in the fly ash, thereby fundamentally solving the problems that the chloride damages a kiln body and influences the sintering quality of clinker;

(2) granulation and desalination, thoroughly solving the problem of difficult dehydration of the washing fly ash

The present invention concreties fly ash into lumps by hydraulic cementing material, concretes fly ash powder into fly ash spherical particles by using the mechanical strength established by fly ash and cementing material, soaks the fly ash spherical particles with clear water after the fly ash spherical particles are fully solidified, so that salt in the fly ash spherical particles is fully leached, and finally the particles are taken out from the soak solution, thereby realizing solid-liquid separation, and achieving the purpose of washing and desalting. Fundamentally solves the problem of difficult desalination caused by strong water absorption of the superfine powder material and difficult solid-liquid separation during the conventional washing fly ash desalination.

(3) Realizes the high-efficiency utilization of the waste incineration fly ash

The waste incineration fly ash based desalted cement raw material ball can be directly used for firing cement clinker, simplifies a plurality of technical links of cement clinker production, and has extremely high industrialization efficiency.

Detailed Description

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

Example 1

On the premise of selecting 20 percent of waste incineration fly ash and 15 percent of P.O 42.5.5 ordinary portland cement, the precise mixing proportion (by mass percent) of raw material balls is designed according to the chemical composition of the raw materials and three major values of the raw cement preparation: 20% of waste incineration fly ash, 62% of limestone, 3% of iron powder and 15% of P.O 42.5.5 ordinary portland cement;

mixing the components, adding water and a water reducing agent into the mixture at normal temperature, and stirring to obtain a dry and thick paste, wherein the addition amount of the water is 15% of the total mass of the waste incineration fly ash, the calcium raw materials and the iron powder, and the doping amount of the water reducing agent is 1% of the total mass of the waste incineration fly ash, the calcium raw materials and the iron powder;

pouring the paste into a granulator to prepare spherical particles with the particle size of 3-20mm, and standing the spherical particles to be desalted for 7 days to fully solidify the spherical particles until the spherical particles are not dispersed and not slimmed when meeting water;

and pouring the fully solidified particles into a clean water tank to be soaked for 1 hour, wherein the solid-to-liquid ratio of soaking is 1:5, so that salt in the particles is fully leached out, and the fly ash-based desalted cement raw material ball is obtained.

The content of chloride ions in the fly ash-based desalted cement raw material ball is measured to be 0.13 percent by a fluorescence analyzer, the chloride is removed sufficiently, and the quality requirement of the fired cement clinker is met.

Example 2

On the premise of selecting 25 percent of waste incineration fly ash and 13 percent of P.O 52.5.5 ordinary portland cement, the precise mixing proportion (by mass percent) of raw material balls is designed according to the chemical composition of the raw materials and three major values of cement raw material preparation: 25% of waste incineration fly ash, 59% of limestone, 3% of iron powder and 13% of P.O 52.5.5 Portland cement;

mixing the components, adding water and a water reducing agent into the mixture at normal temperature, and stirring to obtain a dry and thick paste, wherein the addition amount of the water is 20% of the total mass of the waste incineration fly ash, the calcium raw materials and the iron powder, and the doping amount of the water reducing agent is 0.5% of the total mass of the waste incineration fly ash, the calcium raw materials and the iron powder;

pouring the paste into a granulator to prepare spherical particles with the particle size of 3-20mm, and standing the spherical particles to be desalted for 7 days to fully solidify the spherical particles until the spherical particles are not dispersed and not slimmed when meeting water;

and pouring the fully solidified particles into a clean water tank to be soaked for 1 hour, wherein the solid-to-liquid ratio of soaking is 1:5, so that salt in the particles is fully leached, and the fly ash-based desalted cement raw material ball is prepared.

The content of chloride ions in the fly ash-based desalted cement raw material ball is measured to be 0.18 percent by a fluorescence analyzer, the chloride is removed sufficiently, and the quality requirement of the fired cement clinker is met.

Example 3

On the premise of selecting 30 percent of waste incineration fly ash and 10 percent of P.I 52.5 Portland cement, the precise mixing proportion (by mass percent) of raw material balls is designed according to the chemical composition of the raw materials and three major values of cement raw meal preparation: 30% of waste incineration fly ash, 57% of limestone, 3% of iron powder and 10% of P.I 52.5 portland cement;

mixing the components, adding water and a water reducing agent into the mixture at normal temperature, and stirring to obtain a dry and thick paste, wherein the addition amount of the water is 20% of the total mass of the waste incineration fly ash, the calcium raw materials and the iron powder, and the doping amount of the water reducing agent is 0.5% of the total mass of the waste incineration fly ash, the calcium raw materials and the iron powder;

pouring the paste into a granulator to prepare spherical particles with the particle size of 3-20mm, and standing the spherical particles to be desalted for 7 days to fully solidify the spherical particles until the spherical particles are not dispersed and not slimmed when meeting water;

and pouring the fully solidified particles into a clean water tank to be soaked for 1 hour, wherein the solid-to-liquid ratio of soaking is 1:5, so that salt in the particles is fully leached, and the fly ash-based desalted cement raw material ball is prepared.

The content of chloride ions in the fly ash-based desalted cement raw material ball is measured to be 0.08 percent by a fluorescence analyzer, the chloride is removed sufficiently, and the quality requirement of the fired cement clinker is met.

The above description is only a preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, and any simple modifications or equivalent substitutions of the technical solutions that can be obviously obtained by those skilled in the art within the technical scope of the present invention are within the scope of the present invention.