Research On Dilute Sulphuric Acid Concentration Technique In Acid Making With Gas And Design&Application Of Industrial Plant

As one of the fundamental and most important chemical materials in chemical industry,sulfuric acid is honored as “Mother of Chemical Industry”, while smelting off-gas acid occupieslarge proportion in the sulfuric acid production industry. According to statistics[1], smeltingoff-gas acid occupies26.7%of the total and is showing a year-on-year growth of10.4%. Alongwith the development of nonferrous metallurgy toward large scale and industrialization, thematched system for acid making with gas will be larger and larger and acid making will alsooccupies an important position in Chinese sulfuric acid industry gradually[2]. It is expected thatsulfuric acid produced by smelting gas will be increasing stably during the “Twelfth Five-year”period.Furnace gas purification section of acid making with gas mostly adopts the5%dilute spentsulfuric acid (referred to as “waste acid” for short, similarly hereinafter) generated duringacid-washing process, with the amount of about20-100L/t[3]. Such waste acid contains notonly sulfuric acid and a lot of mine dust, but also harmful substances, including arsenic,fluorine, etc., which may cause seriously results if not properly treated. However, theconcentration of waste acid can better avoid the production of waste residue and effectivelyrecycle the sulfur resource in waste acid. In the meanwhile, concentration of waste acidgradually attracts more and more attention as people enhance environmental protectionawareness and enterprises improve economic benefits, therefore research on recycle ofconcentrated waste acid is of very great significance. On such basis, this thesis aims atdeveloping a new technique of processing waste acid from acid making with gas, with thedesign and implementation divided into three stages: first is sulfuration and purification ofwaste acid, the second refers to design of industrial plant for concentrating dilute sulphuric acidand the last stage is industrial pilot test of concentrating the sulfurized and purified waste acid.During the purification, sulfuration method is mainly used for purifying waste acid so as toremove arsenic, fluorine and other detrimental impurities in waste acid; during the design ofindustrial plant, industrial pilot test unit for concentrating dilute sulphuric acid is designedthrough theoretical calculation and in combination with practical situations; and duringconcentration stage, the concentration unit is installed and commissioned with experiment performed to discuss the factors influencing dilute sulphuric acid concentration anddemonstrate its application in actual cases.