Selective separation recovery technology of heavy metal in electroplating sludge containing chromium

Abstract

The invention relates to a selective separation recovery technology of heavy metal in electroplating sludge containing chromium. The selective separation recovery technology of the heavy metal in theelectroplating sludge containing the chromium specifically comprises the steps that (1) the sludge containing the chromium and carbonate are subjected to mix roasting under a certain temperature, andiron sources are supplemented appropriately; (2) hydrothermal reaction is carried out on a solid obtained in the step (1) and an alkaline mineralizing agent; (3) after solid-liquid separation is carried out on turbid liquid obtained in the step (2) by using magnetic force, a diluted acid solution (pH is 3.5-5.0) is added into the solid for calcium removal, and concentration and crystallization arecarried out for recovering the chromium after liquid dezincification; and (4) after the magnetic separation of the turbid liquid in the step (3) is carried out, mixed reaction is carried out on the solid and a concentrated acid solution (pH is 2-3.5); and after the magnetic separation of the obtained turbid liquid is carried out, the solid is a nickel ferrite product, and copper is recovered in aliquid mode. According to the selective separation recovery technology of the heavy metal in the electroplating sludge containing the chromium, doping regulation and control of metal elements in thesludge in spinel class materials (M (II) N (III) 2O4 (M=Ni, Cu, Zn, Ca; N=Cr, Fe, Al)) is realized through comprehensive regulation and control of the roasting temperature and a hydrothermal mineralizing agent, so that the selective separation recovery technology of the heavy metal is realized. Meanwhile, after the sludge is subjected to a roasting / hydrothermal combined technology, the solid has higher magnetic force, and the difficulty of solid-liquid separation in the technology is reduced.

Description

technical field [0001] The invention relates to a selective separation and recovery process for heavy metals in chromium-containing electroplating sludge, and belongs to the field of solid waste disposal and resource utilization. Background technique [0002] Electroplating sludge refers to heavy metal-containing sludge waste generated after electroplating sewage treatment, and is included in the seventeenth category of hazardous waste in the national hazardous waste list. At present, wastewater treatment plants mainly use chemical reduction, flocculation and precipitation treatment for chromium-containing electroplating wastewater, that is, using a reducing agent (such as ferrous sulfate) to first reduce Cr(VI) to Cr(Ⅲ), and then adding a precipitant (such as quicklime) to reduce Cr(VI) to Cr(Ⅲ). Cr(Ⅲ) was removed from wastewater in the form of Cr-OOH precipitation. In addition to Cr(III), the obtained electroplating sludge often contains iron oxyhydroxides. At the same t...

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