the mixed waste acid before granulating the foregoing results are listed in the table 3 the weight of liquid in waste acid can be reduced by the method for solidifying and stabilizing waste acid of the invention in the step of s 230 the weight of waste acid containing phosphoric acid before condensing is 1571 g total weight of waste acid containing fluoroboric acid is 215 g applied amount of barium hydroxide is 210 g and the weight ratio of the applied amount of the total solidifying agent to the mixed waste acid is 30 1 after solidifying the compression strength of the solidified product which formed after 3 days and after 28 days are 25 kg and 28 kg cm 2 respectively furthermore in the water resistance test of the sample which the compression strength is 74 kg per square centimeter the result of compression strength after dipping in water for three months is 53 5 kg cm 2 it indicated that the solidified product of waste acid formed by the method of the invention has improved weather resistance and water resistance characteristics as shown in table 4 the granule is formed by the first solidifying agent and the efficiency of solidification would not be influenced in the steps shown in fig2 a half of waste acid is inactivated and then another half of waste acid is combined therewith to solidify heat of acid base reaction and rapid setting caused by heat can be prevented to influence the quality of the solidified product of waste acid so that the compression strength of the solidified product can be improved fig3 shows a basic flow.