Research Of Preparation Of Urea Potassium Phosphate From Wet-process Phosphoric Acid By P-K-bearing Shale

Soluble potassium resource is much shortage in our country,while insoluble potassium mineral resources is so rich.Developing insoluble potassium,which can add potassium resource,is attached great importance.This paper used a kind of waste ore bed during phosphate mining,potassium — containing shale and low — grade phosphaterock were up and below it.Developing and utilizing this kind of potassium-containing shale could add soluble potassium resources in markets.What's more,much of phosphate rock is lowgrade.Combined potassium —containing shale and low—grade phosphate rock to make salts contained potassium and phosphorus was mentioned in this paper,which solved the problem of wasting potassium resources and the rational use of low—grade phosphate rock.Analysis methodsof sodium tetraphenylborate gravimetric method and quimociac gravimetric method werementioned in this paper.It studies the effects of extracting potassium under the normal temperature and pressure,from potassium-rich shale and phosphate rock by coupled sulfuric acid and phosphoric acid.Then process of wet phosphoric acid technology on urea potassium phosphate was explored,as well as the process of pretreatment and clarification on potassium dihydrogen phosphate.The main experimental results were as follows:(1)It was a process of extracting potassium under the normal temperature and pressure,which was from potassium-rich shale and phosphate rock by coupled sulfuric acid and phosphoric acid,the optimum conditions were obtained: mass ration of potassium-rich shale to phosphate ore of 0.8,ratio of liquid-to-solid was 3,concentration of sulfuric acid was 50%,reaction temperature was 120?,and reaction time was 5h,extracting ratio of potassium of 76.08% was obtained.The orthogonal experiment can concluded that the order of the influence of several factors on the experimental sequence is reaction time,sulfuric acid concentration,mass ratio,ratio of liquid-to-solid.(2)Pretreatment of synthesis technology on potassium dihydrogen phosphate for lowering the acidity of reaction fluid,the effects of reaction temperature,reaction time and washing times on reaction between mines and acid solution were studied.The optimum conditions were that reaction temperature of 40?,reaction time of 2h and washing four times.What's more,Using p-k bearing shale was better than phosphate ore for lowering the acidity of reaction fluid.(3)Technology of liquid phase and solid phase countercurrent was used during cycling experiments for lowering the acidity of reaction fluid with p-k bearing shale,extracting ratio of phosphorus of 86.05% and ratio of potassium of 52.24% was obtained.118.32% of the theoretical amount of sulfuric acid was accounted for actual consumption of sulfuric acid.(4)Clarification thickening process of synthesis technology on potassium dihydrogen phosphate,pH of mother liquid was adjusted by using potassium hydroxide,also the effects of decreasing acidity of mother liquid on content of iron,aluminum,magnesium was studied.The pH of 4.0-4.2 was best for reaction.Heated,concentrated and filtered,then purity of urea potassium phosphate could obtain 98.89%,which was better.(5)Process of urea potassium phosphate by using urea and potassium dihydrogen phosphate was explored,included reaction temperature,reaction time,reaction rotating velocity and crystallization time.the optimum conditions were obtained: reaction temperature was 70?,reaction time was 80 min,reaction rotating velocity was 200r/min,and crystallization time was 12 h.