Abstract stone coal vanadium industry in recent decades is newly created, its production process is not yet fully mature, the corresponding supporting environmental protection technology and equipment is not complete. This paper firstly proposes the closed-loop treatment technology and process of acid wastewater, and provides reference materials for the technical research of the Vanadium Process Research Institute and the Vanadium Plant. Key words stone coal extraction vanadium acid wastewater closed loop treatment Before the turn of the century, vanadium products were in a slow upward trend. As of the mid-1990s, China's vanadium production capacity was 1.3-1.5 million tons, mainly concentrated in large enterprises. The environmental pollution problem was not serious. After the mid-1990s, with the The international vanadium price has risen sharply. At the beginning of this century, China's total output of vanadium pentoxide was about 20,000 tons. Currently, the production capacity of 50,000 tons is conservatively estimated. Especially after the 21st century, China's vanadium industry is developing more rapidly. With the development of the vanadium industry, the environmental problems have become increasingly serious. Although the country has formulated corresponding industrial policies, it is mainly ordered to close some small vanadium plants and improve the industry access policy. However, some pollution accidents in the vanadium industry have occurred in Hunan and Shaanxi, and the local ecological environment has been seriously damaged. These accidents are mostly vanadium-bearing vanadium-type enterprises. The production process of vanadium-added vanadium has been at the stage of exploration, and it has been transformed from a small-scale production mode with a short production history. The large-scale industrial production process is not yet fully mature, but with the constraints of resources and environment, the investment in stone coal vanadium extraction equipment is small, the production cost is low and comprehensive utilization, and there will be a certain scale of development. 1. Current status of treatment of vanadium acid waste water from stone coal 1.1 adsorption tail liquid ingredients The tailings of vanadium leaching solution of stone coal after vanadium extraction by resin or the raffinate after extraction of vanadium contain a large amount of residual acid and sulfate. According to the analysis of the ore components of many vanadium plants, the chemical composition of the tail liquid can be indirectly understood. It can be seen ore composition liquid, the first type is of SiO2, the second category is AL, Fe, Mg metal, the third category is S, P anionic, fourth category is H2SO4. The calcination, additive and sulfuric acid concentration have a great influence on the impurity content in the raw liquid, but the composition is almost the same. Stone coal stone composition (%) 1.2 tail liquid lime neutralization treatment Lime neutralization treatment is a commonly used method for extracting vanadium from stone coal. Acidic tail liquid and lime are neutralized under alkaline conditions. Metal oxides and calcium hydroxide form metal oxide precipitates and water are separated, sulfur, phosphorus anions and calcium. Generating new salt still However, it is dissolved in the tail liquid and cannot be separated; sulfuric acid and lime form calcium sulfate dissolved in the tail liquid, and silica is also dissolved in the tail liquid. Therefore, the use of lime neutralization does not separate the impurities from the tail liquid, but only plays a role in adjusting the pH value. The lime neutralization method does not separate and waste resources, which is an undesirable treatment. It is difficult for the chemical precipitation method to separate impurities from the sulfuric acid system, and the residual sulfuric acid is separated from the tail liquid by a retardation method. 2. Adsorption tail liquid closed loop treatment process 2.1 Process flow The pH of the acid immersion liquid is about 0.5-1.0, and the vanadium content is about 1-5g/L. After ion exchange or extraction, the acidic tail liquid contains a large amount of metal impurities and impurities such as SiO2. These impurities are dissolved in the acidic tail liquid. In the acidic system, heavy metal ions do not precipitate and cannot be separated. The residual acid in the tail liquid and the corresponding sulfate are separated by an acid recovery machine, and the recovered regenerated acid is returned to the leaching process to supplement a part of the new acid for recycling. The neutral wastewater enters the sewage station, and the mud cake separated by flocculation and pressure filtration is used as a resource for recycling. The wastewater can be discharged from the leaching slag flushing water or treated with the integrated wastewater, or can be treated as an acid recovery machine after the membrane treatment. The system is closed loop. 2.2 Acid separation and recycling Using the principle of special packing retardation separation, the acidic tail liquid enters the acid separation and recovery equipment, the filler blocks the sulfuric acid on the filler, the metal ions flow out with the solution, and the tail liquid becomes near neutral metal wastewater. According to the user's demand, the next step is to proceed. In the process, the sulfuric acid on the filler is dissolved in water, and the solution is discharged to form a regenerated acid, which is returned to the acid leaching step for recycling. Acid stock separation data Acid tail liquid separation curve Acid tail liquid separation solution 3. Summary The residual sulfuric acid in the tail liquid is the main reason that hinders the treatment effect. The acid separation and recovery equipment separates the residual acid from the tail liquid and recovers it and returns it to the production process, which not only turns waste into treasure, saves resources, but also extracts vanadium wastewater for stone coal. Governance, realize closed loop of adsorption tail liquid, solve key technologies and equipment, and lay a foundation for the next step of resource recovery and diversified production of vanadium plants.
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