Method for coagulating boric acid and borate solution and coagulant used in this method

摘要

PROBLEM TO BE SOLVED: To disclose a method for coagulating a mixture by forming in advance polyborates from boron species in boric acid and borate solution and then mixing uniformly an inorganic coagulation agent with a special composition into the solution and the coagulating agent used in this method. SOLUTION: The pH value of a boric acid or borate solution is controlled to 7 to 10 and the solution is concentrated so that the water content in the solution is below 30% and all boron species are kept in solved state to form a polyborates solution with high polymerization factor. Then, chemicals such as divalent or higher metal oxide, hydroxide or salts or one kind or complex powder of several kinds of complex of those chemicals is uniformly mixed with the borate solution as coagulating agent to prepare a slurry capable of hardening, and the slurry is coagulated.