Study On Process Optimization Of Nickel Recovery From Electroplating Sludge

With the development of science and technology and the improvement of economic strength in our country,the electroplating industry is developing rapidly in our country.This means that more and more electroplating wastewater will be produced,and electroplating sludge,as a solid waste produced after electroplating wastewater treatment,contains a variety of heavy metal elements.The content of valuable metals in electroplating sludge can even exceed some rich ores.If electroplating sludge is directly treated as hazardous waste for landfill treatment,there will not only be leakage,environmental damage,and human health safety issues,but also resources.Of waste.Among them,electroplated nickel has high uniformity,wear resistance and corrosion resistance,so it is widely used in industrial production.Electroplating sludge is listed as the seventeenth category of hazardous waste in my country’s "National Directory of Hazardous Wastes",so its harmless disposal and resource treatment are widely concerned.In this paper,the nickel-containing electroplating sludge treated by an environmental protection company in Lianyungang was used as the raw material,and sulfuric acid was used as the leaching agent.After acid leaching,electrolysis,extraction,stripping,and chemical precipitation,the process of obtaining nickel carbonate products was studied.First of all,this article studies the basic properties of electroplating sludge,and determines its moisture content,leaching toxicity,corrosivity,p H and heavy metal content.Research shows that:(1)the moisture content of electroplating sludge is51.6%,the p H value of electroplating sludge is 7.88,and the leaching toxicity of nickel is 0.624 mg/L;(2)the dry sludge contains 42.34% nickel and 4.74% iron.By studying the basic properties of electroplating sludge,it lays a foundation for the leaching of electroplating sludge and the recovery of heavy metals.Secondly,research on the acid leaching,electrolysis,extraction-reverse extraction-precipitation and nickel recovery process of electroplating sludge.(1)Research and analyze the solid-liquid ratio,leaching temperature,leaching time,p H,raw material particle size and The influence of factors such as the number of acid leaching on the leaching rate.The electroplating sludge was tested with a 4mol/L sulfuric acid solution,a liquid-to-solid ratio of 2:1(m L:g),and a rotation speed of25r/min.The results showed that the leaching rate of Cu and Ni in the electroplating sludge under this condition Reaching over 99%,the experiment measured 0.072g/L nickel ion and 0.068/L copper ion.The residual sulfuric acid concentration in the leachate is about 1mol/L,which meets the requirements of the electrolysis production process.(2)The influence factors of the electrolysis of the leachate,the best electrolysis parameters are obtained through experiments: the voltage is 1.6V,and the electrolysis time is 3h.Under these conditions,there is almost no conversion of ferrous ions and trivalent chromium ions,which meets the process parameters.In addition,the number of times that the nickel in the filter residue is returned to leaching is investigated.The experiment shows that the process parameters are better when the number of times of returning to the leaching of the filter residue is 12 times.(3)In the process of extracting nickel with extractant,study the influence of controlling the initial concentration of nickel,p H of the aqueous phase,extraction equilibrium time and other factors on the extraction of nickel.Studies have shown that the p H of the solution is 4.5,the concentration of P204 extractant is 3.0 mol/L,the phase ratio is controlled at 1:2,and the extraction equilibrium time is 3 minutes,and the extraction rate of nickel reaches 96%.(4)Sulfuric acid was used for back extraction.The results showed that the concentration of sulfuric acid was 1 mol/L,the ratio of O/A was 2:1,and the back extraction time was 3 minutes.At this time,the back extraction rate reached 99%.Finally,soda ash was added.Produce nickel carbonate precipitation.(5)The waste slag generated from the treatment and disposal of electroplating sludge is transformed into regenerated gypsum through process technology.The mixture of regenerated gypsum,clay,mountain soil and coal gangue are used to make bricks,and the leaching toxicity of the bricks is determined.Its leaching concentration is 0.06mg/L,which realizes the harmlessness and resource utilization of waste residue.After calculating the benefits of this process,an average of 931 yuan per ton of electroplating nickel-containing sludge can be saved.This method provides an idea for recovering nickel from electroplating sludge,realizes the resource utilization of solid waste,and meets environmental protection requirements.