CN119972722A

CN119972722A - A method for treating fly ash using ironmaking slag

Info

Publication number: CN119972722A
Application number: CN202510222192.9A
Authority: CN
Inventors: 刘宏博; 王雪娇; 俞海明; 王强; 刘文胜; 谭广志; 宿宁; 刘仁博
Original assignee: Chinese Research Academy of Environmental Sciences
Current assignee: Chinese Research Academy of Environmental Sciences
Priority date: 2025-02-27
Filing date: 2025-02-27
Publication date: 2025-05-13

Abstract

The invention discloses a method for treating fly ash by utilizing iron-making slag, and relates to the two technical fields of iron-making slag treatment technology and resource utilization of fly ash generated by waste incineration. The invention adopts an innovative process method, in the process of iron-making slag treatment, fly ash is added into high-temperature iron-making slag as a tempering raw material of the iron-making slag, and the fly ash is converted into components of the iron-making slag by utilizing the high temperature of the iron-making slag to carry out innocent treatment on the fly ash, so that the innocent conversion and subsequent recycling of the fly ash in the process of iron-making slag treatment are realized, and the effective utilization of the heat energy of the iron-making slag is realized.

Description

Method for treating fly ash by utilizing iron-smelting slag

Technical Field

The invention relates to a method for treating fly ash by utilizing iron-making slag, and relates to the two technical fields of iron-making slag treatment process and resource utilization of fly ash generated by garbage incineration.

Background

The solid residue after the garbage incineration treatment accounts for 30% -35% of the total amount of garbage, wherein the bottom ash accounts for 25% -30% and the fly ash accounts for 2% -5%. The waste incineration fly ash refers to the residues of the trapped matters of the flue gas purification system of the waste incineration plant and the sedimentation at the bottoms of the flue and the chimney, contains a certain amount of dioxin, soluble heavy metals and salts, belongs to HW18 dangerous wastes (772-002-18 household waste incineration fly ash) in national hazardous waste directory, and can be safely landfilled after being subjected to harmless treatment in advance. At present, research on recycling of fly ash is found in literature and report. The paper entitled "resource utilization profile of municipal refuse incineration fly ash" is published in the journal of environmental impact evaluation in period 4 of 2019 in reference document (1) Luo Renhong, the paper has been developed for recycling utilization of domestic and foreign refuse incineration fly ash in cement, concrete, ceramic lightweight aggregate and building materials, the fly ash is a novel material which can be considered as a part of base materials for replacing road construction materials, but also needs to be supported by related policies, and the content expression of the following further research is needed, and (2) Du Jian in the journal of river nan building material in period 4 of 2017 in the paper entitled "cement curing technology for treating refuse incineration fly ash" is published, in the paper, the effect of the silicate cement on the curing of municipal refuse incineration fly ash is analyzed, and the result shows that after the fly ash is cured by silicate cement, the compressive strength of a curing body is reduced along with the increase of the fly ash doping amount, and heavy metal ions such as Pb and Cd are more easily leached from the curing body, so as to further improve the curing effect of cement paste. The method is characterized in that (3) Fan Yanling, zheng Penghui and Zhou Wen are provided in journal of resource conservation and environmental protection in the 4 th period of 2020, and the paper entitled "harmless and recycling treatment technology review of waste incineration fly ash" is provided in the paper, and the waste incineration fly ash harmless and recycling utilization is still in a starting stage in China, and a plurality of technical difficulties are not overcome, such as large cement solidification and capacity increase, incomplete destruction of dioxin substances by a chemical agent stabilization method, unstable heavy metal effect and high cost by a fusion method, unstable technical effect of water heat treatment and the like, and the recycling reutilization is not widely applied. "content expression.

As is clear from the above-described publications, there is no process for utilizing iron-making slag in cooperation with utilization of fly ash as a resource.

Blast furnace slag is a by-product of pig iron smelting. When the blast furnace is used for iron making, raw materials such as iron ore, fuel (coke), fluxing agent (limestone and dolomite) and the like are added. When the furnace temperature reaches 1400-1600 ℃, the fluxing agent reacts with iron ore at high temperature to become liquid phase, gangue, ash, fluxing agent and other impurities which cannot enter pig iron form slag with good fluidity, the slag is separated from the molten iron due to different densities (molten iron 6.8-7.0 g/cm ³ and slag 2.2-3.2 g/cm ³), and slag floating on the molten iron in the liquid phase is separated through a slag avoiding device and discharged from a slag hole.

The treatment process of the iron-making slag mainly comprises two modes of hot splashing treatment (dry slag) and water quenching treatment. The water dreg process includes mainly 4 kinds of processes including bottom filtering process, yinba process, lasa process and drawing process.

Referring to literature (1) Gao Yang, noble and permanent, song Chunyan, hu Binsheng, wang Yawen, five authors published papers entitled "blast furnace slag sensible heat recycling current situation and hope" in journal of mineral comprehensive utilization at period 1 of 2018, wherein "the traditional water quenching method in China does not recycle slag sensible heat at all, and a large amount of heat is dissipated in the white land". Under the condition, scientific researchers at home and abroad perform multiple experiments, and the experiments can be mainly divided into two directions, namely a physical heat exchange method and a chemical recovery method. The physical heat exchange method mainly realizes that the blast furnace slag is collected through a specific energy carrier, and the sensible heat recovery chemical recovery method is to directly utilize slag and sensible heat to produce products with high added value. Compared with the former, the chemical recovery method is more efficient in recovering sensible heat and can reflect comprehensive utilization of blast furnace slag. The content expression of 'Wang Haifeng, zhang Chunxia, ji Yuanhong, dai Xiaotian, the strict gilding, five authors published papers on the journal of steel in 6 th 2007 entitled' blast furnace slag treatment technology and new development trend ', and the' traditional blast furnace slag water treatment technology has the defects of high water consumption, environmental pollution, air and water pollution, unable recovery of heat energy and the like. The new dry process treatment blast furnace slag is to be developed, so that not only can the new water be greatly saved, but also the sensible heat of the blast furnace slag can be recovered, and in addition, the same effect as that of the traditional water treatment blast furnace slag can be achieved after the blast furnace slag is granulated. "content expression;

as is clear from the above discussion of the literature, there is no technology for cooperatively treating fly ash by utilizing the waste heat of iron-making slag.

Disclosure of Invention

The invention aims to provide a method for treating fly ash by utilizing iron-smelting slag, which can cooperatively treat the fly ash generated by a municipal waste incinerator by utilizing the waste heat of the iron-smelting slag, realizes the process aim of fully absorbing the municipal fly ash by a steel mill, and is beneficial to the cooperative development of municipal waste incineration industry and municipal steel enterprises.

The technical scheme adopted by the invention is that the method for treating the fly ash by utilizing the iron-making slag is implemented according to the following steps:

1) Firstly, purchasing calcium carbonate powder, and after the granularity of the calcium carbonate powder is 0.5-1.0 mm, pulling the calcium carbonate powder to a dry powder pelletizing production line for later use;

2) Purchasing waste edible oil (commonly called swill-cooked dirty oil) and transporting to a dry powder pelletizing production line for standby;

3) Uniformly mixing fly ash, waste edible oil and calcium carbonate powder according to the mass percentage ratio of 90:5:5, pressing into pellets with the size of 5 mm-10 mm by adopting a high-pressure dry powder ball pressing machine, and pulling and conveying the pellets to the vicinity of a slag hole of a 2500m ³ blast furnace for later use;

4) And (3) beginning iron-making slag discharge, adding 50-150 kg of the pellets into the liquid iron-making slag in the slag discharge ditch, wherein the rest iron-making slag treatment process is unchanged.

The inventors found the following scientific phenomena through research:

1. The slag temperature of iron making is up to 1400-1600 ℃, the specific heat capacity of slag is about 1.2 KJ/(Kg. DEG C), and the alkalinity of iron making slag is about 1.0, so that the slag is alkaline slag with low melting point and good fluidity, and is favorable for adding fly ash into liquid iron making slag and carrying out chemical reaction of physical thermal decomposition dioxin of the iron making slag, thereby realizing the purpose of heat energy recycling of the iron making slag;

2. The formation condition of the fly ash is that the fly ash is formed under the high temperature condition of about 850-1100 ℃ in the garbage incinerator, under the high temperature environment, the crystal structure of each mineral in the fly ash is coarse, the fly ash is added into high temperature iron-making slag, slag forming reaction of mineral recombination occurs between the fly ash and the iron-making slag, the required chemical reaction heat is less, and the secondary slag forming reaction between the fly ash and the iron-making slag can be satisfied;

3. The iron-making slag is a reducing slag, and small iron beads formed in the iron-making process are dispersed in the slag, and the content of the small iron beads accounts for about 2% -10% of the amount of the iron-making slag. The small iron beads are recycled through a magnetic separation mode in the process of recycling the iron-making slag, and most of the iron-making slag contains vanadium-titanium oxides. The characteristics are favorable for the reduction of heavy metals in the fly ash, the melting of the heavy metals into small iron beads for recovery, and the cracking and harmless conversion of dioxin in the fly ash;

4. According to the findings, the inventor takes fly ash as a main raw material, calcium carbonate powder with the mass percent of 5 percent is added into the fly ash, waste edible grease is taken as a binder, the fly ash is produced into pellets with the size of 5-10 mm by using a dry powder ball press, the pellets are added into iron-making slag in the slag discharging process of an iron-making blast furnace, dioxin in the fly ash is decomposed by utilizing the high temperature of the iron-making slag, heavy metal in the fly ash is reduced by utilizing the alkaline characteristic of the iron-making slag, and metal small iron beads in the iron-making slag are fused, so that the aim of recycling is fulfilled, and the fusion development of the synergistic treatment of dangerous waste in the iron-making industry is realized.

The innovation points of the invention are as follows:

1. The inventor finds that the high-temperature alkaline iron-smelting slag can promote harmless conversion of harmful heavy metal elements in the fly ash, can decompose scientific phenomena of dioxin and organic matters, adds the fly ash into the iron-smelting slag for harmless conversion, and finally converts the fly ash into a part of the iron-smelting slag, thereby realizing resource utilization of the fly ash, and belongs to the industry initiating technology;

2. In order to realize that the fly ash can be added into the iron-smelting slag to quickly complete the decomposition of dioxin, the inventor utilizes waste edible oil and fat as a binder, and adds calcium carbonate to pelletize the fly ash, and utilizes the characteristics of quick cracking and burning of the waste edible oil and fat after being heated and thermal fragmentation of the calcium carbonate to increase a reaction interface for chemical reaction between fly ash pellets and liquid iron-smelting slag and improve the reaction speed;

3. the added calcium carbonate powder is used as a chlorine fixing agent after the decomposition of the dioxin in the fly ash, and oxides of Ti and V in the iron-making slag can also play a role of the chlorine fixing agent, so that the possibility of synthesizing the dioxin again after the decomposition of the dioxin in the fly ash can be eliminated;

4. the inventor utilizes the characteristic that 2% -10% of small iron beads (most of the small iron beads are liquid) in the iron-making slag, and the heavy metal in the fly ash can be melted into the small iron beads after being reduced, so that the small iron beads can be recycled in a subsequent magnetic separation production line.

The mineral organization of the fly ash is close to that of the iron-making slag, after harmful substances in the fly ash are eliminated, the fly ash can be converted into the component parts of the iron-making slag, and the component parts are used as the resource utilization of the iron-making slag, so that the purpose of resource utilization of the fly ash is realized, and the environmental protection significance is great.

The invention has the beneficial contributions that 1, the fly ash is cooperatively treated by utilizing the high-temperature liquid slag of iron making, the harmless conversion of the fly ash is realized while the treatment process of the iron making slag is not influenced, the treatment cost of dangerous waste is saved, the land occupation contradiction caused by the fact that most of the fly ash is used for landfill at present is solved, the significance of social development is great, 2, the production amount of the iron making slag is great, the iron making slag amount produced by producing one ton of molten iron is usually 250-500 kg, 125-250 ten thousand tons of iron making slag is produced by one 500 ten thousand tons of long-flow iron and steel enterprises, 6-25 ten thousand tons of fly ash can be utilized as resources by utilizing the iron making slag each year, the technical purpose of completely absorbing the urban fly ash by urban steel factories is realized, and the cooperative development of urban garbage incineration industry and urban iron and steel enterprises is facilitated.

Detailed Description

The embodiment of the invention is illustrated by a 2500m ³ blast furnace of a certain iron and steel enterprise,

A method for treating fly ash by utilizing iron-making slag is implemented according to the following steps:

Claims

1. A method for treating fly ash using ironmaking slag, characterized in that it is implemented according to the following steps:

1) First, purchase calcium carbonate powder with a particle size of 0.5-1.0 mm, and then transport it to the dry powder pelletizing production line for use;

2) Purchase waste edible oil and transport it to the dry powder pelletizing production line for use;

3) After the fly ash, waste edible oil and calcium carbonate powder are evenly mixed in a mass percentage of 90:5:5, they are pressed into 5mm-10mm pellets using a high-pressure dry powder pelletizing machine and transported to the vicinity of the ^2500m3 blast furnace slag outlet for standby use;

4) When the ironmaking slag is tapped, add the above pellets to the liquid ironmaking slag in the blast furnace slag ditch, 50-150 kg of the above pellets are added to each ton of ironmaking slag, and the rest of the ironmaking slag treatment process remains unchanged.