| The waste liquor of removing arsenic from yellow phosphorus is produced in the process of producing low-arsenic phosphorus by oxidation method. According to' analysis, waste liquor contains phosphoric acid, phosphorous acid as well as arsenic, asenious acid and other impurities.The paper studied to utilize method of the waste liquor with removing arsenic, redox method, concentration and crystallization.In this paper, firstly, the author studied removal of arsenic in the waste liquor by chemical precipitation method with P2S5. The experimental study indicated that the arsenic content in waste water reduced from 230ppm to 0.35ppm, dearsenization rate is 99.85%; The optimum technical conditions for dearsenization as follows: When the waste capacity is 100mL, the De-Arsenic P2S5 quality is 0.081g, reaction temperature is 80℃, reaction time 110min, stirring speed is300r/min.Based on reducibility of phosphorous acid, the paper researched technology of to oxidation sub-phosphoric acid to phosphoric acid in the waste on the basis of studing on oxidizing pure phosphorus acid. The author studied effects of the amount of hydrogen peroxide, temperature, reaction time, reaction solution pH value and the stirring speed on the oxidation ratio of phosphorous acid in the waste liquor by using hydrogen peroxide as oxidant. The optimum oxidation conditions:When the waste treatment capacity is 100mL, the oxidant H2O2 dosage is 30mL, pH value is 7, stirring speed is 350r/min, reaction temperature is 70℃, reaction time is 120min.In this technical condition, the oxidation of H3PO3 in the waste liquor can become H3PO4 by using hydrogen peroxide as oxidant, oxidation rate can reach 87.62%, and the reproducibility was good.This paper also studied the technology of manufacturing diammonium phosphate after arsenic was removed and phosphorus acid was oxidized in the waste liquor of purifying yellow phosphorus. The optimum process conditions manufacturing diammonium phosphate are:the pH value of neutralized phosphoric acid and ammonia is 8.6, the reaction temperature is 85℃, reaction time is 40min, stirring speed is 250 r/min, the crystallization temperature is 25℃. The process under the condition of the system to get them diammonium phosphate product, its appearance is white powder, particle size mainly distributed in the 50.9μm-62.6μm between the chemical analysis and X diffraction analysis showed that the compound mainly (NH4) 2HPO4 form, and the product quality in the P2O5, N to reach GB 10205-2001 DAP product high grade quality requirements.In addition, on the basis of studing solubility of potassium phosphate, sodium salt and ammonium salt the paper carried on separation exploratory experiments of potassium salt in the waste liquid based on the solubility. The studies have shown that the accumulated crystal quality of monopotassium phoaphate (dry weight) is 18.9530g, its recovery rate can reach 91.63% by neutralization waste liquid with potassium hydroxide directly. Samples were proved that there is no sub-phosphate and crystals are orthophosphate by analysis.After removing arsenic and other harmful impurities elements from waste liquor this paper has adopted two ways to use waste water containing phosphoric acid, phosphorous acid and other valuable components, one way is to reduce phosphorous acid as orthophosphoric acid using oxidation and than to be utilization; Another way is to make phosphoric acid and phosphorous acid separate directly or directly produce the phosphate and phosphite then isolate into phosphoric acid and phosphorous acid phosphate, and phosphite. Because the two ways can get the high value use of phosphorous acid and phosphite, this can not only make full use of waste, energy-saving, emission reduction, clean production, protecting the environment but also producing a high economic efficiency, improve process of yellow phosphorus refined dearsenization, therefore the technology researched has a good practical application value. |
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