CN-122010435-A - Device and method for dechlorination of gypsum and separation of fly ash

Abstract

The invention relates to the technical field of solid waste treatment and resource utilization, in particular to a device and a method for removing chlorine from gypsum and separating fly ash. Preparing gypsum raw materials containing chlorine and fly ash into emulsion, placing the emulsion into a reactor, applying direct current to carry out electrochemical treatment to remove chloride ions in the anode, stopping electrifying, carrying out gravity sedimentation layering by utilizing density difference, and sequentially separating supernatant, fly ash slurry and bottom purified gypsum. The device comprises a reactor, an electrochemical system and a layered discharge device, and a nickel molybdenum oxide catalyst can be optionally matched to improve dechlorination efficiency. The method integrates dechlorination and impurity separation into the same flow, does not need a large amount of water washing, avoids the generation of high-chlorine wastewater, can obviously reduce the chlorine content of gypsum and effectively separate the fly ash, greatly improves the purity and whiteness of the desulfurized gypsum, and realizes the efficient recycling of solid wastes.

Inventors

• ZHANG YEQING
• Zhang Yuxiaole

Assignees

• 淄博彧源机电科技有限公司

Dates

Publication Date

20260512

Application Date

20260331

Claims (10)

1. 1. A method for dechlorinating gypsum and separating fly ash, which is characterized by comprising the following steps: a) Mixing gypsum raw materials containing chlorine and fly ash with water to prepare gypsum emulsion; b) Placing the gypsum emulsion in a reactor, applying direct current to the gypsum emulsion through a cathode and an anode arranged in the reactor, and performing electrochemical treatment on the gypsum emulsion to remove chloride ions in the gypsum emulsion, so as to obtain a treated mixture; c) After stopping applying the direct current, carrying out gravity sedimentation layering on the treated mixture; d) Separating the layered material to obtain purified gypsum.
2. 2. The method of gypsum dechlorination and fly ash separation according to claim 1, characterized in that in step b) the electrochemical treatment further comprises flowing or contacting the gypsum emulsion over a catalyst disposed between the cathode and anode.
3. 3. The method for dechlorination of gypsum and separation of fly ash of claim 2, wherein the catalyst is a nickel molybdenum oxide mixture.
4. 4. The method for dechlorination of gypsum and separation of fly ash according to claim 3, wherein the mass ratio or mole ratio of nickel to molybdenum in the nickel-molybdenum oxide mixture is 1:1, and the catalyst is supported on a ceramic honeycomb carrier.
5. 5. The method for dechlorination of gypsum and separation of fly ash according to claim 1, wherein the energy density of the direct current applied in the step b) is 1mW/L to 2kW/L, and the treatment time of the direct current applied in the step b) is 10 seconds to 1200 seconds.
6. 6. The method for dechlorination and separation of gypsum and fly ash according to claim 1, wherein in the step d), the separation step comprises sequentially discharging supernatant liquid of the upper layer, slurry of the middle layer and slurry of the bottom layer after sedimentation and delamination.
7. 7. A gypsum dechlorination and fly ash separation device, comprising: A reactor body for containing a gypsum emulsion; an electrochemical system, comprising: an electrode assembly comprising at least a pair of cathodes and anodes disposed within the reactor body; the direct current power supply is electrically connected with the electrode group and is used for supplying power to the electrode group; and the separation and discharge device is used for carrying out layered discharge on the settled layered materials after the treatment is finished.
8. 8. The gypsum dechlorination and fly ash separation apparatus of claim 7, further comprising a catalytic system comprising a catalyst disposed between the cathode and anode.
9. 9. The apparatus for dechlorination of gypsum and separation of fly ash according to claim 8, wherein the catalyst is a nickel molybdenum oxide mixture and is supported on a ceramic honeycomb carrier.
10. 10. The apparatus of claim 7, wherein the cathode and anode are made of one or more materials selected from the group consisting of nickel, molybdenum, silver, copper, platinum, stainless steel, carbon, and graphite.

Description

Device and method for dechlorination of gypsum and separation of fly ash Technical Field The invention relates to the technical field of solid waste treatment and resource utilization, in particular to a device and a method for removing chlorine from gypsum and separating fly ash. Background Wet desulfurization (FGD) of flue gas from coal-fired power plants is a main technique for controlling sulfur dioxide emission, and the yield of by-product desulfurized gypsum (mainly comprising calcium sulfate dihydrate, caSO 4·2H2 O) is huge. In theory, the desulfurized gypsum is a high-quality resource with higher grade, and can replace natural gypsum to be used for producing building material products such as gypsum boards, gypsum mortar, cement retarders and the like. However, in practical application, the recycling utilization rate of the desulfurized gypsum is not ideal, a large amount of gypsum is piled up, and not only precious land resources are occupied, but also environmental risks exist. The main bottleneck limiting the high-value utilization of the waste water is the impurities contained in the waste water, wherein chlorine ions (Cl -) and fly ash are the most harmful. The harm of chloride ion is that the chloride ion in the desulfurized gypsum is mainly derived from fire coal and process water. High levels of chloride ions (up to 10000ppm in some areas) can cause a series of serious problems for downstream products and production processes: The quality of the product is affected, and chlorides such as calcium chloride, magnesium chloride and the like have strong hygroscopicity, and can cause the phenomenon of 'halogen return' of gypsum products (such as gypsum boards and plastering gypsum), namely surface moisture absorption, frosting and water discharge, thereby causing the problems of blackening, mildew, falling off and the like of a facing layer and seriously affecting the attractiveness and durability of a building. In the production process, high-concentration chloride ions can cause serious corrosion to metal equipment such as a stirrer, a mould and the like, so that the service life of the equipment is shortened. More seriously, when used for preparing concrete admixture or plastering mortar, chloride ions in gypsum migrate and corrode reinforcing steel bars in buildings, and structural safety poses a long-term threat. The fly ash is fine particles generated in the coal burning process, and part of the fly ash enters a desulfurization system along with flue gas and is mixed into gypsum. The presence of fly ash has a major impact: The purity and whiteness of the product are directly reduced by the incorporation of the fly ash, and the color of the fly ash is usually gray black, so that the whiteness of the gypsum product is obviously reduced, and the product cannot meet the requirements of high-grade building materials or chemical raw materials on the color. The product performance is that unburnt carbon and other components in the fly ash can influence key performance indexes such as setting time, mechanical strength and the like of the gypsum product. In order to solve the problems, the prior art mainly adopts a water washing method. Although the water washing method can remove part of chloride ions, the water washing method has the defects of huge water consumption, large amount of wastewater with high chlorine content which is difficult to treat, secondary pollution, limited efficiency for removing the chloride ions adsorbed on the surface of gypsum crystal and difficult to effectively separate fine fly ash with the size similar to that of gypsum particles. Therefore, developing an economic, efficient and environment-friendly gypsum purification technology to realize the synchronous removal of chloride ions and fly ash has become a technical problem to be solved urgently in the industry. Disclosure of Invention According to the defects in the prior art, the invention aims to provide a device for removing chlorine from gypsum and separating fly ash, which organically combines two processes of removing chlorine and separating impurities into one core device, has short process flow and relatively simple operation control, can be designed into intermittent or continuous production, and meets the requirements of different scales. The invention also aims to provide a method for dechlorinating gypsum and separating fly ash, which can remarkably improve the purity and quality of gypsum, reduce the negative influence on the environment and realize the high-value and resource utilization of solid wastes such as desulfurized gypsum. The invention is realized by adopting the following technical scheme: the method for dechlorinating gypsum and separating fly ash comprises the following steps: a) Mixing gypsum raw materials containing chlorine and fly ash with water to prepare gypsum emulsion; b) Placing the gypsum emulsion in a reactor, applying direct current to the gypsum emulsion through a cathode and an