阅读说明：本技术 一种利用氟化铝生产尾气洗涤液再生氟化铝的生产工艺 (Production process for regenerating aluminum fluoride by using aluminum fluoride production tail gas washing liquid ) 是由 孟文卜 刘贻宝 令小强 魏学 刘继鹏 吴志晶 安岳峰 葛斐 于 2020-04-01 设计创作，主要内容包括：本发明涉及一种利用氟化铝生产尾气洗涤液再生氟化铝的生产工艺,是将氟化铝生产尾气洗涤液与氧化铝在合成槽内进行固液吸附反应；将吸附反应后的的固、液混合物过滤,得到固体氟化铝软膏,将氟化铝软膏烘干,出料,冷却包装得到氟化铝成品；将过滤后的母液排入废水槽经循环冷却降温后,用于氟化铝生产尾气洗涤系统补水,实现水的循环利用。该工艺有效回收了氟化铝生产系统尾气洗涤液中的氟元素,并且该工艺操作简单,工艺过程中无废水排放,实现水的经济循环利用,降低了生产成本,并利于环保。(The invention relates to a production process for regenerating aluminum fluoride by utilizing tail gas washing liquid in aluminum fluoride production, which is to carry out solid-liquid adsorption reaction on the tail gas washing liquid in the aluminum fluoride production and aluminum oxide in a synthesis tank; filtering the solid-liquid mixture after the adsorption reaction to obtain solid aluminum fluoride ointment, drying the aluminum fluoride ointment, discharging, cooling and packaging to obtain an aluminum fluoride finished product; and discharging the filtered mother liquor into a waste water tank, and performing circulating cooling to replenish water for an aluminum fluoride production tail gas washing system so as to realize the recycling of water. The process effectively recovers the fluorine element in the tail gas washing liquid of the aluminum fluoride production system, is simple to operate, has no wastewater discharge in the process, realizes the economic recycling of water, reduces the production cost, and is beneficial to environmental protection.)

1. A production process for regenerating aluminum fluoride by utilizing a washing liquid of tail gas generated in the production of aluminum fluoride is characterized by comprising the following steps of:

(1) carrying out solid-liquid adsorption reaction on the aluminum fluoride production tail gas washing liquid and aluminum oxide in a synthesis tank;

(2) filtering the solid-liquid mixture after the adsorption reaction in the step (1) to obtain solid aluminum fluoride ointment, drying the aluminum fluoride ointment, discharging, cooling and packaging to obtain an aluminum fluoride finished product;

(3) discharging the filtered mother liquor obtained in the step (2) into a waste water tank, and performing circulating cooling to supplement water for an aluminum fluoride production tail gas washing system so as to realize the recycling of water;

(4) discharging redundant mother liquor in the waste water tank into a neutralization tank, and adding lime for neutralization reaction;

(5) and (4) filtering the solid-liquid mixture obtained after the neutralization reaction in the step (4) to obtain solid calcium fluoride ointment, mixing the calcium fluoride ointment into wet fluorite, and drying to obtain the anhydrous hydrofluoric acid production raw material.

2. The production process for regenerating aluminum fluoride by using the washing liquid of the tail gas from the production of aluminum fluoride according to claim 1, which is characterized in that: in the step (1), the concentration of hydrofluoric acid in the cleaning solution is 2.5-3.0 g/L, the mass-to-volume ratio of the alumina to the cleaning solution is 2.6-3.2 g/L, the reaction temperature is 70-85 ℃, and the pH of the reaction end point is = 4-5.

3. The production process for regenerating aluminum fluoride by using the washing liquid of the tail gas from the production of aluminum fluoride according to claim 1, which is characterized in that: in the step (2), the drying temperature is 550-650 ℃.

4. The production process for regenerating aluminum fluoride by using the washing liquid of the tail gas from the production of aluminum fluoride according to claim 1, which is characterized in that: in the step (3), the temperature of the mother liquor is 20-25 ℃ after being cooled.

5. The production process for regenerating aluminum fluoride by using the washing liquid of the tail gas from the production of aluminum fluoride according to claim 1, which is characterized in that: in the step (4), the concentration of hydrofluoric acid in the mother liquor is 0.5-1 g/L.

6. The production process for regenerating aluminum fluoride by using the washing liquid of the tail gas from the production of aluminum fluoride according to claim 1, which is characterized in that: in the step (4), the neutralization reaction temperature is 20-25 ℃, the reaction time is 0.5-1.0 h, and the pH value of the reaction end point is 6-7.

7. The production process for regenerating aluminum fluoride by using the washing liquid of the tail gas from the production of aluminum fluoride according to claim 1, which is characterized in that: and (5) discharging the filtered filtrate into a water storage tank for supplementing water to a cooling system.

Technical Field

The invention relates to a process for regenerating fluoride salt in tail gas washing liquid, in particular to a process for regenerating aluminum fluoride by using tail gas washing liquid produced by aluminum fluoride.

Background

Aluminum fluoride is generally directly prepared by reacting hydrogen fluoride gas and aluminum hydroxide in a fluidized bed, and the method for preparing aluminum fluoride can obtain high-quality products and is rapidly developed in China in recent years. However, a large amount of tail gas containing hydrogen fluoride is generated after the hydrogen fluoride reacts with the aluminum hydroxide, the tail gas needs to be washed to ensure that the tail gas reaches the standard and is discharged, and a large amount of fluorine-containing wastewater with low concentration is generated in the tail gas washing process. At present, the treatment of the fluorine-containing wastewater mainly comprises the production of cryolite, although the production cost is low, the cryolite is gradually eliminated by the market and cannot meet the market demand, a large amount of cryolite stock can be caused by continuous production, a large amount of capital overstocks are caused, great economic benefit loss is caused, and great environmental protection pressure is caused due to the fact that the cryolite cannot be properly treated. Therefore, a new process and a new method are urgently needed to be found for transforming the original treatment mode of the tail gas washing liquid in the aluminum fluoride production into another product so as to achieve the purposes of wastewater treatment, fluorine recycling and cost reduction.

Disclosure of Invention

Aiming at the technical problems, the invention provides a process for regenerating aluminum fluoride by utilizing a tail gas washing liquid generated in the production of aluminum fluoride, the aluminum fluoride generated by the process effectively replaces cryolite, and the aim of treating fluorine-containing wastewater is fulfilled.

The invention relates to a process for regenerating aluminum fluoride by using a washing liquid of tail gas in aluminum fluoride production, which comprises the following steps:

(1) the aluminum fluoride production tail gas washing liquid in the washing tank and the aluminum oxide are subjected to solid-liquid adsorption reaction in the synthesis tank, wherein the reaction formula is Al₂O₃+6HF=2AlF₃+3H₂O；

(2) Filtering the solid-liquid mixture after the adsorption reaction in the step (1) to obtain solid aluminum fluoride ointment, drying the aluminum fluoride ointment, discharging, cooling and packaging to obtain an aluminum fluoride finished product;

(3) discharging the filtered mother liquor obtained in the step (2) into a waste water tank, and performing circulating cooling to supplement water for an aluminum fluoride production tail gas washing system so as to realize the recycling of water;

(4) discharging redundant mother liquor in the waste water tank into a neutralization tank, and adding lime for neutralization reaction;

(5) and (4) filtering the solid-liquid mixture obtained after the neutralization reaction in the step (4) to obtain solid calcium fluoride ointment, mixing the calcium fluoride ointment into wet fluorite, and drying to obtain the anhydrous hydrofluoric acid production raw material.

Further, in the step (1), the concentration of hydrofluoric acid in the cleaning solution is 2.5-3.0 g/L, the mass-to-volume ratio of the alumina to the cleaning solution is 2.6-3.2 g/L, the reaction temperature is 70-85 ℃, and the pH of the reaction end point is = 4-5.

Further, in the step (2), the drying temperature is 550-650 ℃.

Further, in the step (3), the temperature of the mother liquor is 20-25 ℃ after being cooled.

Furthermore, in the step (4), the concentration of hydrofluoric acid in the mother liquor is 0.5-1 g/L.

Further, in the step (4), the neutralization reaction temperature is 20-25 ℃, the reaction time is 0.5-1.0 h, and the pH value of the reaction end point is 6-7.

And further, in the step (5), the filtered filtrate is discharged into a water storage tank and is used for supplementing water to a cooling system, so that the primary water consumption is reduced, and the economic recycling of water is realized.

The invention has the beneficial effects that:

1. the process effectively recovers the fluorine element in the tail gas washing liquid of the aluminum fluoride production system, converts the fluorine element into the aluminum fluoride, realizes the purpose that the aluminum fluoride replaces cryolite and achieves the treatment of the fluorine-containing wastewater, and reduces the environmental pollution caused by the discharge of fluorine.

2. According to the process, the redundant mother liquor in the wastewater tank is added with lime, so that the fluorine element is further recovered, the generated calcium fluoride can be used as a raw material for anhydrous hydrofluoric acid production, and the production cost is saved.

3. The process is simple to operate, no wastewater is discharged in the process, the economic recycling of water is realized, the production cost is reduced, and the process is beneficial to environmental protection.

Drawings

FIG. 1 is a flow chart of the present invention.

Detailed Description

The present invention is further illustrated by the following specific embodiments.

(1) Discharging the cleaning solution of tail gas generated in the production of aluminum fluoride in the cleaning tank into a No. 1 tank of a synthesis tank, wherein the concentration of hydrofluoric acid in the cleaning solution is 2.5-3.0 g/L, uniformly adding aluminum oxide into the No. 1 tank of the synthesis tank for adsorption reaction, wherein the reaction formula is Al₂O₃+6HF=2AlF₃+3H₂And O, the adding amount of the alumina is 2.6-3.2 g/L, stirring is carried out at the stirring speed of 220r/min, then solid and liquid overflows from the No. 1 synthesis tank enter the No. 2, No. 3 and No. 4 synthesis tanks to realize full reaction, the reaction temperature is controlled to be 70 ℃, and the pH of the reaction end point is = 4-5.

(2) Filtering the solid-liquid mixture after the adsorption reaction by a plate-and-frame filter to realize solid-liquid separation to obtain solid aluminum fluoride ointment, discharging the aluminum fluoride ointment into an aluminum fluoride ointment box, drying by a flash evaporation dryer at the drying temperature of 550 ℃ and the discharging temperature of 180 ℃, conveying the materials into a finished product bin through a secondary conveying process, naturally cooling and packaging to obtain the finished product of aluminum fluoride.

(3) Mother liquor obtained by filtering after adsorption reaction is discharged into a waste water tank, and is used for replenishing water for an aluminum fluoride production tail gas washing system after being cooled to 25 ℃ through circulating cooling, so that the cyclic utilization of water is realized.

(4) And (3) allowing redundant mother liquor in the waste water tank to enter a neutralization tank, wherein the concentration of hydrofluoric acid in the mother liquor is 0.5-1 g/L, adding lime for neutralization reaction, and arranging 2 neutralization tanks in series to ensure full reaction, wherein the pH value at the end point of the reaction is 6-7, the reaction temperature is 25 ℃, and the reaction time is 1.0 h.

(5) And filtering the solid-liquid mixture after the reaction is finished by a plate and frame filter to obtain solid calcium fluoride ointment, mixing the calcium fluoride ointment into wet fluorite, drying the mixture to be used as a production raw material of anhydrous hydrofluoric acid, discharging the filtrate filtered by the plate and frame filter into a water storage tank for supplementing water to a cooling system, reducing the consumption of primary water and realizing the economic recycling of the water.