阅读说明：本技术 利用全固废胶凝材料的飞灰制粒方法和充填集料 (Fly ash granulation method and filling aggregate by using all-solid-waste cementing material ) 是由 曲效成 冯志 刘浩 季毛伟 熊威 于 2019-10-23 设计创作，主要内容包括：本发明公开了利用全固废胶凝材料的飞灰制粒方法和充填集料。所述飞灰制粒方法包括以下步骤：由一定比例的固体废弃物制备胶凝材料；将飞灰和所述胶凝材料分别从制粒装置的第一侧和第二侧加入所述制粒装置,并混合均匀；从所述制粒装置的第三侧喷洒入水,直至形成重量浓度为70～85％的料浆；在所述第三侧添加减水剂重量浓度为0％-1％的水雾至形成飞灰颗粒。本发明的飞灰制粒方法协同处理了工业固体废弃物和垃圾焚烧飞灰,实现了以废治废,方法步骤简单易操作,能耗低,所用的设备简单,成本低,环保无污染。(The invention discloses a fly ash granulation method and filling aggregate by using a full solid waste cementing material. The fly ash granulation method comprises the following steps: preparing a gelled material from a certain proportion of solid waste; adding fly ash and the cementing material into a granulating device from the first side and the second side of the granulating device respectively, and uniformly mixing; spraying water from the third side of the granulating device until slurry with the weight concentration of 70-85% is formed; and adding water mist with the weight concentration of 0-1% of the water reducing agent to the third side until fly ash particles are formed. The fly ash granulation method provided by the invention cooperatively treats industrial solid waste and waste incineration fly ash, realizes the treatment of waste by waste, and has the advantages of simple steps, easiness in operation, low energy consumption, simple used equipment, low cost, environmental friendliness and no pollution.)

1. A fly ash granulation method by using a full solid waste cementing material is characterized by comprising the following steps:

(1) preparing a gelled material from a certain proportion of solid waste;

(2) adding fly ash and the cementing material into a granulating device from the first side and the second side of the granulating device respectively, and uniformly mixing;

(3) spraying water from the third side of the granulating device until slurry with the weight concentration of 70-85% is formed;

(4) and adding water mist with the weight concentration of 0-1% of the water reducing agent to the third side until fly ash particles are formed.

2. The fly ash granulation method according to claim 1, wherein the water reducing agent in step (4) is one or more of lignosulfonate water reducing agents, naphthalene water reducing agents, melamine water reducing agents, sulfamate water reducing agents, fatty acid water reducing agents and polycarboxylate water reducing agents.

3. A fly ash granulation method according to claim 1, wherein the solid waste comprises, based on the total weight of the solid waste: 20-70% of slag, 0-50% of steel slag, 5-30% of industrial byproduct gypsum, 5-20% of tailings and 5-20% of red mud.

4. A fly ash granulation method according to any of claims 1 to 3, wherein the cementitious material further comprises one or more of clinker, granulated electric furnace phosphorous slag, granulated ferrochromium slag, fly ash, carbide slag, caustic sludge, coal gangue.

5. A fly ash granulation process according to claim 3, wherein the slag comprises the following chemical components, based on the total weight of the slag: 38 to 49 percent of CaO and SiO₂26％～42％，Al₂O₃6％～17％，MgO 1％～13％，MnO 0.1％～2％，FeO 0.07％～2.5％，S 0.2％～1.5％。

6. A fly ash granulation method according to claim 3, wherein the steel slag comprises the following chemical components, based on the total weight of the steel slag: 5 to 30 percent of tricalcium silicate, 5 to 30 percent of dicalcium silicate, 10 to 38 percent of RO phase, 2 to 8 percent of ferric oxide, 0.5 to 5 percent of calcium hydroxide, 0.5 to 5 percent of ferric hydroxide, 0.01 to 3 percent of free calcium oxide, 0.01 to 10 percent of calcium carbonate, 0.01 to 8 percent of magnesium carbonate, 0.01 to 3 percent of ferric carbonate and the balance of 0.01 to 3 percent.

7. A fly ash granulation method according to claim 1, wherein in the step (2), the weight ratio of the fly ash to the gelling material is 1: 1-3: 1.

8. A fly ash granulation method according to claim 1, the granulation device being a disc granulator.

9. A fly ash granulation process according to claim 8, wherein the disc angle of the disc granulator is between 60 ° and 70 °.

10. A filled aggregate comprising fly ash particles made by the fly ash granulation method of any of claims 1 to 9.

Technical Field

The invention relates to the technical field of solid waste utilization and cementing materials, in particular to a fly ash granulation method by utilizing a full solid waste cementing material.

Background

With the rapid development of economy, the continuous increase of urban population and the gradual diversification of residential consumption structures in China, the generation amount and the accumulation amount of urban domestic garbage increase year by year. The garbage incineration method has the obvious advantages of volume reduction, weight reduction, energy recovery and the like, and becomes one of the mainstream modes for harmless treatment of domestic garbage in China. Incineration fly ash is a dangerous solid waste containing a large amount of harmful elements generated after domestic garbage is treated by an incineration method, and reduction and harmless treatment are required.

Scientific research institutions at home and abroad carry out deep research on the aspects of waste incineration fly ash disposal and resource utilization, and part of the technologies have successfully realized commercial application. In canada, most fly ash is transported to hazardous waste disposal sites for harmless disposal; in Denmark, fly ash of a dry or semi-dry flue gas purification system belongs to hazardous waste, and is generally filled in a polyethylene bag and then separately buried in a special landfill (containing a percolate collecting system and a bottom liner, and often an impermeable cover layer); 18 ten thousand tons of waste incineration fly ash is produced in 2006 in Sweden, and two harmless treatment modes are mainly adopted: after stabilization, the waste is filled and exported to Norway for use as a neutralizer for acidic waste; most fly ash in the netherlands is landfilled in non-hazardous waste landfills, but about 40% of fly ash from electrostatic precipitators is used as a filler for asphalt concrete (the incorporation ratio is small), but since 1998, fly ash cannot be landfilled directly without treatment; in germany, flue dust and flue gas cleaning system fly ash are hazardous wastes that are disposed of in designated hazardous waste landfills or underground disposal sites (such as old salt mines or dedicated wells for disposal of refuse), and to reduce the release of dust from the surface of stored materials, the fly ash is usually packaged or moistened. In japan, fly ash is classified as "household garbage requiring special management", and is not directly landfilled, and can be landfilled in a landfill only after being treated by a fly ash treatment method (4 types of cement solidification method, chemical agent stabilization method, melting method, and acid or other solvent extraction method) established by the health and welfare department and passing a leaching test. In addition, the fly ash from incineration of domestic garbage in developed countries in europe and america has a low content of alkali metal chloride, and research is mainly focused on using cement kiln calcination to solidify the fly ash as a building material. In Asian countries, because the content of plastic substances in the household garbage is high, the content of chlorides, especially alkali metal chlorides, in the incineration fly ash is high, the strength and the soaking durability of a solidified body obtained by a cement solidification method are poor, and the long-term fixing effect of heavy metals is poor.

At present, two disposal modes of cement kiln cooperative disposal and solidification safe landfill are mainly adopted for waste incineration fly ash in China. The pretreatment of the incineration fly ash of the household garbage by the cooperation of the cement kiln and the treatment needs dechlorination, so that the cost is high and the treatment amount is limited; before the domestic garbage incineration fly ash is safely buried, solidification/stabilization treatment is mostly needed. The solidification/stabilization technology is to reduce the toxicity and the mobility of hazardous wastes by adding a curing agent or a stabilizing agent, and currently, the more mature solidification/stabilization technology comprises the following steps: cement solidification, lime solidification, plastic solidification, melt solidification, self-cementation solidification, chemical stabilization, and the like. The curing/stabilizing technology in the prior art has the problems of high cost, large capacity-increasing ratio and large occupied area for subsequent safe landfill. The safe disposal problem of the household garbage incineration fly ash is urgently needed to be solved by the society.

The cementing filling material is generally prepared by taking broken stones, river sand or gobi aggregate or tailing sand as aggregate, mixing the aggregate with cementing agents such as cement, cementing powder and the like by adding water, stirring to form slurry or paste, and conveying the slurry or paste to a filling area in a pipeline pumping or gravity self-flowing mode. The cemented filling material generally contains a certain proportion of aggregate, so that the filling body has higher strength and integrity and higher operation safety, and the recovery rate of ores and the operation efficiency of a stope can be improved while various underground supporting requirements are met. However, the goaf capacity of most coal mines and part of metal mines is far greater than the volume of the mined waste rocks, no proper filling aggregate is arranged around the goaf, and in order to meet the filling index requirements, only stones or river sand can be purchased to be used as the aggregate for filling, so that the filling cost is high. In this case, fly ash granulation is used as the aggregate, so that not only is the fly ash treated in large quantity, but also the cost of filling the aggregate is reduced. The cementing material used for fly ash granulation is generally ordinary portland cement, which has high cost, generates huge economic pressure and causes great harm to the environment. Therefore, the search for low-cost, high-performance and environment-friendly cementing materials to replace cement is an urgent problem to be solved in mine filling.

Chinese patent CN107382239A provides a full solid waste filler for stabilizing fly ash containing dioxin incineration and a preparation method thereof, which utilizes a full solid waste system to prepare a cemented filler for mines, and simultaneously stabilizes fly ash containing dioxin garbage incineration, solving the environmental problems caused by dioxin in the fly ash from garbage incineration and a large amount of land required for landfill, and is characterized in that fly ash is used as a cementing material component, and no reference is made to filling aggregate.

Chinese patent CN109772848A provides a method for disposing municipal refuse incineration ash and fly ash by deep-filling and sealing, which comprises the steps of compressing, granulating, sealing granules and packaging the refuse incineration ash and fly ash, then conveying the refuse incineration ash and fly ash to a mine to be used as main aggregate for mine filling, setting the proportion of material fly ash granules and ash granules according to the strength of a filling body by other filling materials such as an accelerating agent, cement and water, stirring the mixture, and then conveying the mixture to a working face of a mining area from the ground by a complete filling device such as a pipeline and the like for filling.

Disclosure of Invention

The invention aims to provide a method for preparing fly ash particles by using a full solid waste cementing material as a cementing agent and fly ash through a special proportioning process, and filling aggregate comprising the fly ash particles, wherein the filling aggregate can be used as filling aggregate of a mine goaf. The method can treat the fly ash to the maximum extent, can improve the properties of the filling body such as strength, fluidity and the like, and can reduce the using amount of the mine filling cementing material by adopting the filling aggregate, thereby reducing the cost of the mine filling material.

The invention provides a fly ash granulation method by using a full solid waste cementing material, which comprises the following steps:

(2) adding fly ash and the cementing material into a granulating device from the first side and the second side of the granulating device respectively, and uniformly mixing;

(3) spraying water from the third side of the granulating device until slurry with the weight concentration of 70-85% is formed;

(4) and adding water mist with the weight concentration of 0-1% of the water reducing agent to the third side until fly ash particles are formed.

Preferably, the water reducing agent in the step (4) is one or more of lignosulfonate water reducing agents, naphthalene water reducing agents, melamine water reducing agents, sulfamate water reducing agents, fatty acid water reducing agents and polycarboxylate water reducing agents.

The solid waste comprises, based on the total weight of the solid waste: 20-70% of slag, 0-50% of steel slag, 5-20% of tailings and 5-20% of red mud.

The cementing material also comprises one or more of clinker, granulated electric furnace phosphorus slag, granulated ferrochromium slag, fly ash, carbide slag, alkaline residue and coal gangue.

The slag comprises the following chemical components based on the total weight of the slag: 38 to 49 percent of CaO and SiO₂26％～42％，Al₂O₃6％～17％，MgO 1％～13％，MnO 0.1％～2％，FeO 0.07％～2.5％，S 0.2％～1.5％。

The steel slag comprises the following chemical components based on the total weight of the steel slag: 5 to 30 percent of tricalcium silicate, 5 to 30 percent of dicalcium silicate, 10 to 38 percent of RO phase, 2 to 8 percent of ferric oxide, 0.5 to 5 percent of calcium hydroxide, 0.5 to 5 percent of ferric hydroxide, 0.01 to 3 percent of free calcium oxide, 0.01 to 10 percent of calcium carbonate, 0.01 to 8 percent of magnesium carbonate, 0.01 to 3 percent of ferric carbonate and the balance of 0.01 to 3 percent.

In the step (2), the weight ratio of the fly ash to the cementing material is 1: 1-3: 1.

Preferably, the fly ash and the solid waste raw material are pre-dried until the water content is 0.01-0.1%.

The granulating device is a disc granulator. The disc angle of the disc granulator is 60-70 degrees.

The invention also provides a filling aggregate, which comprises the fly ash particles prepared by the granulating method.

The beneficial effects of the above technical scheme are as follows:

the invention realizes that the fly ash is solidified by using the cementing material made of solid industrial waste to replace cement, and the fly ash is further used for preparing the cemented filling aggregate for mines; realizes the synergistic solidification of fly ash and solid industrial waste generated by the incineration of the garbage. The concentration of dioxin in the leachate of the fly ash particles prepared according to the invention is far lower than 30pg/L specified by the American drinking water standard, and the concentration of heavy metal ions and the corrosivity of the leachate are far lower than the related requirements of 'identification standard of corrosive identification of hazardous waste GB 5085.1-2007' and 'identification standard of leaching toxicity of hazardous waste GB 5085.3-2007'; the filling aggregate subjected to harmless curing treatment is filled into the underground mining dead area through the solid-waste cementing material in a synergistic manner, so that large-area land required by a safe landfill is saved; the problems of few sources and high cost of filling aggregates around part of mines are solved, and fly ash generated by burning solidified garbage is treated to a greater degree.

The fly ash granulation method using the total solid waste cementing material of the invention is further explained with the attached drawings.

Drawings

FIG. 1 is a process flow diagram of a fly ash granulation process utilizing total solid waste cementitious material in accordance with the present invention;

fig. 2 is a schematic structural view of a disc granulator in a fly ash granulation method using all solid waste cement according to the present invention.

Detailed Description

Referring to fig. 1, the present invention provides a fly ash granulation method using a total solid waste cement, comprising the steps of:

(1) preparing a gelled material from a certain proportion of solid waste;

(2) adding fly ash and the cementing material into a granulating device from the first side and the second side of the granulating device respectively, and uniformly mixing;

(3) spraying water from the third side of the granulating device until slurry with the weight concentration of 70-85% is formed;

(4) and adding water mist with the weight concentration of 0-1% of the water reducing agent to the third side until fly ash particles are formed.

The solid waste comprises, based on the total weight of the solid waste: 20-70% of slag, 0-50% of steel slag, 5-20% of tailings and 5-20% of red mud.

Specifically, the slag is granular blast furnace slag formed by rapidly cooling slag produced in the metallurgical blast furnace ironmaking process with water, also called water slag or water-quenched slag, and the main chemical composition ranges are as follows: 38 to 49 percent of CaO and SiO₂26％～42％，Al₂O₃6 to 17 percent, MgO 1 to 13 percent, MnO 0.1 to 2 percent, FeO 0.07 to 2.5 percent and S0.2 to 1.5 percent. Other indexes meet the requirements of GB/T18046-2008.

The steel slag is slag generated in the steel-making process, wherein the tricalcium silicate content is C₃S5% -30%, dicalcium silicate content C₂5 to 30 percent of S, 10 to 38 percent of RO phase, 2 to 8 percent of ferric oxide, 0.5 to 5 percent of calcium hydroxide and 0.5 to 5 percent of ferric hydroxide0.01-3% of free calcium oxide, 0.01-10% of calcium carbonate, 0.01-8% of magnesium carbonate, 0.01-3% of iron carbonate and 0.01-3% of others. The other indexes meet the requirements of GB/T20491-.

The industrial byproduct gypsum refers to an industrial byproduct which is generated by chemical reaction in industrial production and takes calcium sulfate (mainly anhydrous and dihydrate calcium sulfate) as a main component, and comprises one or more of desulfurized gypsum, phosphogypsum, fluorgypsum, lemon gypsum and waste ceramic mold gypsum.

The tailings refer to inorganic nonmetallic materials left after valuable metals are subjected to flotation extraction on crushed ores in a metal mine beneficiation process, and the inorganic nonmetallic materials include but are not limited to iron tailings, tungsten tailings, copper tailings, lead-zinc tailings and the like.

The red mud is industrial solid waste discharged after alumina is extracted from bauxite, and comprises Bayer process red mud with high aluminum content in bauxite, Bayer process red mud with low aluminum content in bauxite, sintering process red mud or combined process red mud which is produced by using sintering process or combined sintering process and Bayer process to refine aluminum. The main minerals are aragonite and calcite, and the content is 60-65%.

Preferably, the cementing material also can comprise one or more of 0-30% of clinker, 0-60% of granulated electric furnace phosphorus slag, 0-30% of granulated ferrochromium slag, 0-30% of fly ash, 0-30% of carbide slag, 0-20% of alkaline slag and 0-50% of coal gangue.

According to a specific embodiment, in the step (2), the weight ratio of the fly ash to the cementing material is 1: 1-3: 1, preferably 2: 1.

Specifically, in step (2): the fly ash is fed from a first side (e.g., the left edge) of the disk of the pelletizing apparatus, e.g., disk pelletizer, the cementitious material is fed from a second side (e.g., the upper side), and the pelletizer is turned on to mix the fly ash with the cementitious material uniformly, e.g., for about 60 seconds.

In step (3), a proper amount of water, for example, straight water, is sprayed on the third side (for example, the right side) of the granulating device, for example, a disk of a disk granulator, until the slurry concentration of the material is 70% -85%.

In step (4), water mist with a water reducing agent concentration of 0% to 1% by weight is added, e.g. sprayed, to the third side (e.g. the right side) of the disc of the pelletizing device, e.g. a disc pelletizer, to form fly ash particles.

In particular, referring to fig. 2, the granulation apparatus that can be used in the fly ash granulation method of the present invention may be a disk granulator, which mainly comprises a disk 1, a spray opening 2 and a metering valve 3.

In the above fly ash granulation method of the present invention, the particle size can be adjusted by adjusting the disc angle of the disc granulator. The smaller the angle of the disk, the larger the particle size of the produced fly ash particles, whereas the larger the angle of the disk, the smaller the particle size of the produced fly ash particles. Preferably, in the present invention, the disc angle is controlled to be 60 ° to 70 °, preferably 65 °. Accordingly, the particle size range of the produced fly ash particles is 3mm-100 mm.

Preferably, the preparation method further comprises a curing step, namely placing the prepared particles into a water curing box for curing, wherein the temperature is 20 ℃, the humidity is 96%, and the finished product of the fly ash particles can be obtained after curing to a corresponding age.

The mechanism of action of the above-mentioned cementitious material during the preparation of fly ash particles according to the invention is as follows:

the raw material of the cementing material has a two-phase micro phase-separated structure, wherein Al-O bonds in the glass body are stronger than Si-O bonds, the glass body is easy to dissolve and disperse by an exciting agent, when the coordination number of Al is 6, the bonding strength of aluminum octahedron is stronger, about 50 percent of the bonding strength of Si-O, the activity is higher, when the ground raw material is contacted with OH-with a certain concentration, aluminum tetrahedron and aluminum octahedron are dissolved and dispersed before silicon-oxygen tetrahedron, in addition, Mg²⁺Distributed in cavities of the vitreous body network structure to form an inhomogeneous phase, thus intensifying the disordered arrangement of the microcrystalline phase in the vitreous body and being beneficial to the hydration of the material. The raw material contains most of calcium-rich phase, is a continuous phase, and wraps the discontinuous silicon-rich phase therein to form a structure of a glass body. The calcium-rich phase has higher thermodynamic instability than the silicon-rich phase, and has certain kinetic stability, so that certain activity must be overcome when the calcium-rich phase is damagedAnd (4) energy conversion. In an alkaline environment, the effect of OH-can overcome the decomposition activation energy of the calcium-rich phase, so that the calcium-rich phase is quickly hydrated and decomposed, and the structure of the waste residue vitreous body is damaged; the silicon-rich phase is then gradually exposed to an alkaline medium and undergoes slower hydration and decomposition. The calcium silicate hydrate (C-S-H) of the calcium-rich phase and the silicon-rich phase is continuously formed and grown, so that the structure of the hydrate is continuously enhanced, and the strength of the cementing material is continuously increased. And in C-S-H gel (SiO) which contributes most to the strength of the filling material₂+Al₂O₃) The molar ratio of CaO + MgO is within the range of 0.6 to 0.8. Sufficient research has shown that the higher the ratio in a C-S-H gel in this range, the greater its contribution to the strength of the filler. C-S-H gel is a chain-structured silicate of linked silicon-oxygen tetrahedrons, and is water-quenched in granulated blast furnace Slag (SiO)₂+Al₂O₃) The molar ratio of CaO + MgO is 0.9 or more.

In steel Slag (SiO)₂+Al₂O₃) The ratio of (CaO + MgO + FeO) is very low, typically below 0.15. Therefore, if steel slag is ground into fine powder, the ability of the steel slag fine powder to provide silicon (aluminum) oxygen tetrahedrons for the gel hardening and strength increase of the filler is extremely weak. In the C-S-H gel, not only a large number of silicon-oxygen tetrahedrons can be substituted by aluminum-oxygen tetrahedrons and a certain number of ferrite tetrahedrons, but also calcium ions therein can be substituted by a large number of divalent ions such as magnesium ions, ferrous ions, and the like. Therefore, if the steel slag can be ground into micron-sized fine powder, so that the steel slag can be quickly hydrated, a large amount of divalent metal cations can be provided for a gelling system.

The content of alumina in the granulated blast furnace slag is generally high and is linked to the silica tetrahedra in the vitreous of the blast furnace slag in the form of aluminoxy tetrahedra. When blast furnace slag comes into contact with the higher pH solution formed from steel slag and red mud, aluminotetrahedra tends to depolymerize from the linkage of the silotetrahedra into solution. When more gypsum exists in the system, the crystallization reaction of ettringite can be rapidly generated. The main phases of the red mud are NaOH, NaCl and CaSO₄And the like, which has the positive effects of alkali excitation, inorganic salt excitation and sulfate excitation on slag hydration.

The preparation method of the cementing material comprises the following steps: drying slag, steel slag, industrial byproduct gypsum, tailings, red mud and powder adhesive until the water content is 0.01-0.1%, and then respectively and independently grinding the materials until the specific surface area is 100-600 m²and/Kg, optionally mixing with one or more of clinker, granulated electric furnace phosphorus slag, granulated ferrochromium slag, fly ash, carbide slag, red mud, alkali slag and coal gangue after activation treatment in a mixer. Wherein the activation treatment comprises one or more treatment modes of grinding, calcining and alkali excitation.

As shown in fig. 1 and fig. 2, the invention provides a fly ash granulation method using total solid waste cementing material, which can increase a feasible scheme of large-scale treatment and utilization of fly ash, and simultaneously, the invention uses total solid waste cementing material to replace cement as cementing material for fly ash granulation, thereby solving the problems of high cement cost, large dosage and low early strength of the existing cementing material; the bulk industrial solid wastes such as tailings, slag, steel slag and industrial byproduct gypsum are piled up in large quantities to cause resource waste and environmental pollution, and the problems of high cost, large capacity-increasing ratio, large occupied area of a safe landfill site and the like in the safe disposal process of the waste incineration fly ash are solved.

In particular, the technical effect of the fly ash granulation method according to the present invention is represented in the following aspects:

1. according to the fly ash granulation method, more than 90% of raw materials of the cementing material for preparing the fly ash particles are sourced from industrial solid wastes.

2. The fly ash particles are prepared by adopting the all-solid-waste cementing material, and the fly ash from the incineration of the domestic garbage containing dioxin heavy metal and the like is cooperatively utilized while the industrial solid waste is treated, so that the treatment of waste by waste is realized.

3. The strength of fly ash particles obtained by granulating fly ash generated by burning solidified garbage as filling aggregate meets the requirement of a filling mining method, and meanwhile, the concentration of harmful components in the leachate completely meets the environmental protection standard, so that the harmless treatment is completely realized, and the land area required by safe landfill is saved.

4. The fly ash granulation method is very simple and easy to operate, low in energy consumption, simple in used equipment, low in cost, environment-friendly and pollution-free.

5. According to the fly ash granulation method, the problems of insufficient sources and high cost of part of mine filling aggregates are solved by utilizing fly ash granulation of solidified garbage incineration, the performance of a filling body is improved, the filling cost is reduced, and meanwhile, the solidified fly ash in a goaf is utilized to the maximum extent.

Specific examples will be listed below to representatively illustrate embodiments of the present invention.