FILTER DEVICE FOR WASTE HYDROCHLORIC ACID PICKLING LIQUID

摘要

PURPOSE:To remove SiO2 contained in waste hydrochloric acid pickling liquid used for pickling a steel material and to enable effective use thereof as a raw material for a high-grade ferrite magnetic material by passing said waste liquid through a filter device constituted of an acid resistant tank packed therein with silica gel powder. CONSTITUTION:The waste hydrochloric acid pickling liquid contg. much Fe-component used for pickling a steel material is admitted into an acid resistant tank 1. An acid resistant plate 3 for holding filter media is placed in the tank 1 apart a space 9 from a base 1a and a filter layer 5a consisting of silica gel powder 5 having <=4mm. grain size is provided thereon via an acid resistant filter 4 as the filter medium through which the liquid is passed. The greater part of the SiO2- component contained in the waste liquid is selectively adsorbed and removed therefrom when said liquid passes through the above-mentioned filter layer 5a. The waste liquid contg. virtually no SiO2-component gathers in the space 9 and is taken out through a liquid discharging port 26. The waste liquid is subjected to a roasting treatment or crystallization treatment to recover iron oxide which is used as a raw material for pearlite as a magnetic material.