Process optimization of nickel extraction from hazardous waste

Abstract

Zinc plant residue is a hazardous waste which contains high quantity of nickel and other valuable metals. Process parameters such as reaction time, acid concentration, solid-liquid ratio, particle size, stirring speed and temperature for nickel extraction from this waste were optimized using factorial design. Main effects and their interactions were obtained by the analysis of variance ANOVA. Empirical regression model was obtained and used to predict nickel extraction with satisfactory results and to describe the relationship between the predicted results and the experiment results. The important parameters for maximizing nickel extraction were identifi ed to be a leaching time solid-liquid ratio and acid concentration. It was found that above 90% of nickel could be extracted in optimum conditions.

PROCESSING OF SPENT ZINC-MnO2 DRY CELLS IN VARIOUS ACIDIC MEDIA

“…This result is in agreement with literature data for D2EHPA. 25,27,28,31,42 The graph log D as a function of log [D2EHPA] (Figure 3) shows that the slope is close to 2 for all leachants. The extraction reaction is well established in sulfuric medium: ).…”

“…This is the normal behavior found in sulfuric medium. 25,27,30,31 More than 95 wt.% of Zn(II) was extracted in one stage at pH 2 (HF and HCOOH) and 2.5 (H 2 SO 4 ). More Mn(II) was extracted as pH increased (H 2 SO 4 >> HCOOH > HF), also in agreement with literature data.…”

“…14,16,19 Sulfuric acid is by far the most used leachant. 2,[25][26][27][28][29][30][31][32] It provides high zinc recovery whereas most manganese remains in the insoluble residue (Mn(III) and Mn(IV) compounds). A reductant (such as hydrogen peroxide, sulfur dioxide, oxalic acid, carbohydrates etc.)…”

“…It has been acknowledged as a versatile renewable reagent for green and sustainable chemical synthesis and processes. 41 Leached Zn(II) can be separated from Mn(II) by chemical precipitation, 22,24 solvent extraction (SX) 2,[25][26][27][28][29][30][31]42 or electrowinning. 16,24 Zn(II) extraction using D2EHPA (di-(2-ethylhexyl)phosphoric acid, a cation exchanger) has been studied since the 1980s.…”

SEPARATION OF ZINC FROM MANGANESE BY SOLVENT EXTRACTION FROM ACIDIC LEACHATES OF SPENT ZINC-MnO2 DRY CELLS USING NEUTRAL ORGANOPHOSPHORUS EXTRACTANTS

“…5 Hydrometallurgical processes are usually based on the dissolution of metal phases (essentially Zn and Mn oxides) in aqueous alkali or acidic media. 3,22 Sulfuric acid is by far the most used leachant, followed by hydrochloric acid 10,17,[23][24][25][26][27][28][29][30] Since Mn(IV) is insoluble in acidic and alkaline media, reduction of tetravalent manganese is an important issue in acid leaching step. A reductant (such as hydrogen peroxide, sulfur dioxide, oxalic acid, carbohydrates etc.)…”