The methodological null phosphate rock stone which produces the dry phosphatic fertilizer, the raw materials

摘要

PURPOSE: To achieve the recycling of resources and the preservation of the environment and reduce a production cost and the cost for treating waste material by baking a mixture of a material containing waste phosphoric acid salt generated from a metal surface treating process, silica, and an alkali metal compound or an alkaline earth metal compound at a high temperature. ;CONSTITUTION: A waste phosphoric acid (salt) solution generated in a chemical surface treatment process for steel or aluminum is neutralized with an alkali such as milk of lime and subjected to filtration. The obtained wet cake of calcium phosphate and metal phosphates having 50-80wt.% of water is dried to the water content of 1-10wt.% to obtain a cake of waste phosphoric acid. A raw material mixture obtained by mixing the dried cake with silica, an alkali metal or alkaline earth metal compound, and optionally phosphate rock is added with a calcium compound. After the ratio of P₂O₅ in the waste phosphoric acid cake/P₂O₅ in the raw material mixture is adjusted to ≤50wt.% and the molar ratio of CaO/P₂O₅ in the raw material mixture is to 3-4, the raw material mixture is molten or baked at the temperature of ≥1400°C. The molten or baked material is poured into cold water. The solid is recovered, dried and pulverized.;COPYRIGHT: (C)1996,JPO