System for preparing aluminum compounds using waste sulfuric acid and method thereof

A system for preparing aluminum compounds using waste sulfuric acid, comprising:

• a storage tank, configured for storing and supplying a waste sulfuric acid solution;
• a first reaction tank, communicating with the storage tank via a first feed pipe for receiving the waste sulfuric acid solution, an aluminum source being added into the first reaction tank, the aluminum source reacting with the waste sulfuric acid solution to form an aluminum sulfate solution, the first reaction tank further communicating with a delivery pipe and an impurity removal via a first discharge pipe, thereby directing the aluminum sulfate solution to the delivery pipe or the impurity removal device, the impurity removal device being configured for removing insoluble impurities from the aluminum sulfate solution;
• a second reaction tank, communicating with the impurity removal device via a second feed pipe for receiving the aluminum sulfate solution from which the insoluble impurities have been removed, a sulfate being added and mixed with the aluminum sulfate solution to form an aluminum sulfate double salt solution;
• an evaporator, communicating with the delivery pipe and a second discharge pipe of the second reaction tank for evaporating and concentrating the aluminum sulfate solution from the first reaction tank to form a saturated aluminum sulfate solution or for evaporating and concentrating the aluminum sulfate double salt solution from the second reaction tank to form a saturated aluminum sulfate double salt solution;
• a crystallizer, communicating with the evaporator and the impurity removal device for receiving, cooling and crystallizing the solution from the evaporator or the impurity removal device, thereby obtaining aluminum sulfate crystals or aluminum sulfate double salt crystals;
• a crushing device, communicating with the crystallizer via a crystal conveying pipe for crushing the aluminum sulfate crystals and the aluminum sulfate double salt crystals;
• a screening device, communicating with the crushing device via a transport pipe for sorting the crystals with a particle size less than 50 mesh to be recycled as seed crystals back to the crystallizer and the crystals with a particle size greater than 50 mesh to be output as finished products.