| The caustic soda process is easy to bring a large amount of solid waste of calcium carbonate white mud in the process of producing liquid alkali,and the annual discharge is very large,which has become a major environmental problem faced by enterprises.For the treatment of solid waste from caustic soda production,domestic researchers have applied its solid waste in many aspects to make it comprehensive utilization,but the effect is not significant.In order to solve the problem of secondary pollution and waste of resources caused by solid waste in the caustic soda production process,this project develops a new process for the production of ultra-fine calcium carbonate co-production liquid sodium hydroxide.In the process of caustic soda production,the solid waste is no longer by-product,but the calcium in the raw material is transformed into ultra-fine spindle-shaped calcium carbonate with high added value,and the liquid sodium hydroxide is co-produced.Therefore,the new process not only makes full use of calcium resources,but also solves the problem of environmental pollution.So great practical significance,the caustic soda system enables enterprises to achieve good economic efficiency and outstanding environmental benefits.Calcium carbonate is an inorganic salt industrial product.It is one of the most widely used inorganic fillers,and it is non-toxic,harmless and inexpensive,so it plays an irreplaceable role in the national economy.Because the product ultra-fine calcium carbonate has a spindle-shaped special structure,ultra-fine particle size,grade narrow particle size distribution and high dispersibility,it is an ideal toughening and reinforcing inorganic filler,which can partially replace expensive white powder such as titanium dioxide.The filler can effectively cut costs and improve the performance of the product.Liquid sodium hydroxide is a commonly used reagent in chemical experiments,and is widely used in chemical industry production to promote the development of the national economy.It can be widely used in detergent,paper making,artificial fiber and textile,leather making,petroleum refining and other industries to promote the development of various industries.In this paper,quicklime and trona are used as raw materials for digestion and causticization,and the process and process conditions are studied.The effects of digestion and causticization conditions on the morphology of calcium carbonate and the content of sodium hydroxide were studied,and the product was characterized by scanning electron microscopy(SEM).The single factor experiment method was used to investigate the influence of various factors on the product,and the optimal process conditions were obtained as follows: the temperature of digestive water was 84 ℃,the time of smouldering ash was 40 minutes,the ratio of washing water to trona is 4:1,the total amount of trona is 150 mL,the feeding time was 20 minutes,the causticizing temperature is 70 °C,the causticizing time is 2 h,the additive is sodium citrate,and the additive is added in an amount of 1%.Under these conditions,super-fine spindle-shaped calcium carbonate with small particle size,good dispersion,high whiteness and content of 98.70% was prepared,and liquid sodium hydroxide with content of 10.83% was produced in parallel.On the basis of the experimental research,this article has carried on the capacity of 100 kt superfine calcium carbonate production technology design of the plant.It mainly includes the material balance of each process,the heat balance of the main equipment,the selection and calculation of the main equipment,the design of the pipeline and instrument flow chart,the layout of the equipment of the workshop,and the treatment measures of “three wastes”.Material balance sheet,P&ID flow diagram,equipment list and workshop equipment layout are also drawn. |
