Study On The Preparation Of Chlorine-free Potash By Electrochemical Decomposition

A chloride-free potash fertilizer is a kind of potassium-free potassium fertilizer,mainly including potassium sulfate,potassium nitrate and potassium carbonate.As a major source of potassium,potassium chloride is widely used in tomato,tobacco,potato and other crops.However,there are some limitations in the existing preparation process of chlorine-free potash,such as complex operation conditions,high energy consumption and serious environmental pollution.In this paper,KCl and acid-root salt(nitrate,carbonate and sulfate)were used as raw materials to design a four-compartment electrodialysis membrane reactor,which was prepared by electrochemical decomposition.Firstly,three kinds of potassium chloride(potassium sulfate,potassium carbonate and potassium nitrate)were prepared by electrochemical decomposition in intermittent operation mode.Secondly,on the basis of the intermittent operation mode,the process route of continuous production without chlorine fertilizer was designed,and a green,efficient and economical road was developed for the production of chlorine-free potash fertilizer.The first chapter is the introduction part,mainly elaborates chloride potash production status and the advantages and disadvantages of various existing methods,this paper introduces the several different types of electrodialysis device and mass transfer process,analyzes the electricity production with no fertilizer is the advantage of double decomposition method,puts forward the main purpose of this paper,the research significance and research content.The second chapter mainly discusses the current density,the raw material I cationic type,raw material in the I anionic species on the double decomposition method in the intermittent operation in the process of preparation of no fertilizer product performance and process energy consumption,the influence of current efficiency.The results showed that,firstly,when the current density increased from 10 to 25 mA/cm2,the energy consumption increased from 0.41 to 0.64kW·h/kg,and the product purity of KNO3 increased from 92.36%to 95.91%.Secondly,compared with MgSO4 and Na2SO4,when using(NH4)2SO4 as the source of sulfuric acid,the product quality current of the process is relatively high,while the energy consumption is relatively low.Again,this paper discusses the influence of different anion material NaNO3,Na2CO3 and Na2SO4,The order of average energy consumption is EK2CO3>EK2SO4 ? EKNO3,while that of average current efficiency is ?k2SO4>?K2CO3>?KNO3.in addition,compared with the other two kinds of fertilizer,KNO3 product purity is relative taller;Finally,the economic evaluation results show that the electrochemical decomposition method has a good application prospect in the preparation of chloro-free potash,especially for the production of KNO3 and K2CO3 products.The third chapter mainly discusses the current density,initial concentration-KNO3 isolation room solution and KNO3 compartment water flow on the electrical double decomposition method for continuous operation in the process of preparation of potassium nitrate process energy consumption,product quality,the influence of current efficiency,etc.The results show that,firstly,the purity of KNO3 products increased from 92.70%to 95.93%as the current density increased from 10 to 25 mA/cm2.Meanwhile,the product solution Cl-content decreased,energy consumption gradually increased and current efficiency increased.Second,as the initial concentration-KNO3 isolation room solution rises,the final product concentration solution · KNO3 in every room to rise,is beneficial to reduce the cost late evaporation,the percentage content of K+ in almost the same products,at the same time,the percentage of product impurities in Cl-almost unchanged,current efficiency changed little;Finally,there is little effect on the current efficiency and the percentage content of K+ in the product,and the percentage content of the impurity Cl-.The product solution was purified by graphite electrolysis,and the effect of voltage drop and Cl-initial content on the purification of product solution was investigated.The results show that increasing the voltage drop can shorten the time of the product.Cl-initial content is low,and the product standard time is relatively short.The fourth chapter is the summary and prospect of this paper,experimental innovation and features.Chapter four is the summary and prospect of this thesis,experimental innovation and features.To sum up,the results of this paper show that the electrochemical decomposition method provides a green,efficient and economical way for the production of chlorine-free potash fertilizer.However,the experiments involved in this paper are preliminary studies in the laboratory,and the real implementation of industrial production requires further study of the pilot and even industrial large-scale production.