SU1118707A1 - Method of extracting nickel from rinsing water of electroplating process - Google Patents

Abstract

METHOD FOR EXTRACTION OF NICKEL FROM washing water GALVASH1CHESKIH PRODUCTION comprising sorption nickel of said water elution nickel sorbent sulfuric acid solution, washing the cation exchanger with a solution of alkali, differing ayuschiys in that, with a view to reducing the consumption of reagents and the level of impurities in the filter, simplifying technology sorption lead to a phosphonic acid cation exchanger, elution of nickel is carried out with an equivalent amount of sulfuric acid solution absorbed by the metal, and after washing with alkali, the cation exchanger is washed with citrate neutral Nym buffer solution.

Description

00

o Kj The invention relates to a process for recovering nickel from washings of nickel processes for reuse in a process. A known method of nickel separation from nickel wash waters using ion exchange sorbents Nickel-containing wash waters are passed through a cation-exchange filter in the H or Na form and elute nickel with sulfuric acid at a concentration of 15% and more fl. The disadvantages of this method are significant dilution of the concentrate, increase loads on the cation-exchange filter due to the wash water of the anion exchanger, high losses of nickel and consumption of reagents. The closest to the proposed technical essence and the achieved result is a method for extracting nickel from the wash water of electroplating plants, including sorption of nickel from these waters, eluting nickel from the sorbent with sulfuric acid solution, washing the cation with alkali solution C2. . However, this method is characterized by a significant consumption of acid and alkali, low efficiency of the sorption process, insufficiently complete neutralization of the acidic concentration and the presence of sodium ions in it, complicating its use for nickel bath correction, complexity and complexity of the technology due to the use of filtration and separation of hydroxide. The circuit of the invention is to reduce the consumption of reagents and the content of impurities in the filtrate, simplifying the technology. This goal is achieved by the fact that, according to the method of extracting nickel l from the washing waters of electroplating plants, including the sorption of nickel from these waters, eluting the gel from the sorbent with a solution of sulfuric acid, washing the cation exchanger with an alkali solution, adsorbing on the phosphoric acid cation exchanger, zyroirovanie not. equivalent to the absorbed metal is carried out with a solution of sulfuric acid, and after washing with alkali, the cation exchanger is washed with citrate neutral buffer solution. The method is carried out as follows. As a sorbent in the proposed method, an industrial phosphonic acid cation exchanger of the KRF-20t80 brand is used. having the structure -c1Hg-dHCation exchangers of this type have a high affinity for the hydrogen ion, which determines their low nickel capacity in the H-form. In the proposed method, a preliminary sequential treatment of the sorbent with alkali solutions and citrate buffer solution is carried out, allowing the sorbent to be converted into a form that is actively absorbed by nickel. In this form, the concentration ratio in the sorbent reaches 1.2 at pH, below the pH of precipitation of nickel hydroxide, and the citrate buffer solution is removed from the column with a small volume of water (1-2 volumes of sorbent), which provides a partial capture of citrate by the sorbent, and its buffer the action appears to be maintained during the sorption process. In this case, the sorption process proceeds at a constant pH according to the 2RHNa + Ni (RH) 2Ni + 2Na scheme without further hydrolysis of the Na form. A significantly smaller association of sodium ion with a functional group as compared with the hydrogen ion leads to an acceleration of the sorption process and to a decrease in the residual concentrations of nickel in the filtrate. During desorption, nickel is replaced by hydrogen quantitatively. This makes it possible to obtain a concentrate with a given final nickel concentration, choosing dn elmirovaniya quantities of sulfuric acid solution equivalent to the absorbed metal 2-6%. When nickel is eluted with sulfuric acid of the indicated amount, the adsorbed iron impurities remain in the column. Their removal is carried out with citrate buffer solution in the preparation of the sorbent for the next cycle.

31

It is possible to reuse the date buffer solution after acid correction.

Example 1. A sorption column containing 1 l of the KRF-20t80 cation exchanger is treated with 2 liters of 4% NaOH solution (contact time 20 min). After removing the alkali solution, the column is poured with a solution of citrate buffer (pH 6.6, NaOH 6.1 g / l, citric acid 10.5 g / l). After removing the citrate buffer solution, the column is filled with water and 215 l of nickel-containing wash water of the composition is passed through it, g / l: -H1 0.4; 0.25; Na 0.07; Fe 0.002, at a rate of 150 l / h (contact time 0.01 h) to saturate with nickel. The concentration of nickel in the filtrate is 0.08 mg / l. The amount of nickel absorbed is 86 g or 1.46 mol. 1.46 moles of sulfuric acid (83.2 ml of 94% acid in 3.5 liters of water) are taken for elimination. The resulting concentrate, the composition of which is given in table. 1, is used to adjust nickel plating baths. The sorption column is washed with 10 l of water. The washings are combined with the source nickel-containing waters and the next process cycle is repeated. In subsequent cycles, the following column capacities for nickel are 85, 81, and 86 g / kg. In each subsequent cycle use the same solution of citrate buffer.

Example 2. The sorption column was treated as described in Example 1. Nickel was eluted with 4% sulfuric acid. A concentrate is obtained with a nickel content of 47 g / l, pH 4.5, | degree of desorption of liquor is 98.5%.

Example 3. Sorption kolonnu treated according to example 1.

.707 -4

The residual nickel concentration in the filtrate is less than 0.01 mg / L. Elution of nickel is carried out with 2% sulfuric acid. Get a concentrate with a Nickel content of 23 g / l, pH 4.8, the degree of desorption of 98%.

Example 4 The sorption column was treated as described in Example 1. Nickel was eluted with 6% sulfuric acid. A concentrate is obtained with a nickel content of 68 .g / l, pH 4.3 ,. the degree of desorption of 99%.

The proposed method allows to obtain a concentrate with a lower content of impurities (free sulfuric acid and iron) in comparison with the prototype with lower reagent consumption, as well as to reduce the concentration of nickel in wastewater to the level of sanitary norms (Table 1). In the proposed method, a substantial simplification of the technology is achieved, so the number of main stages of treating nickel-containing wash water and the resulting concentrate is reduced from 8 to 3 (according to the prototype, the following stages of gel hydroxide precipitation, filtering of the precipitate, sorption of nickel, neutralization of part of the concentrate, separation of hydroxide occur nickel, neutralization of the acid concentrate with nickel hydroxide, preparation of the column, and proposed: conversion of the sorbent to the active form, sorption of nickel, nickel zylation.

The proposed method does not use filtering processes that are very laborious and difficult to mechanize.

Comparison of sorption characteristics for various methods of pretreatment of sorbents is given in table. 2

Table 1

The nickel content in the concentrate, g / l for example

one

2

3

48.6

The content of free sulfuric acid in the concentrate, g / l,

pH of concentrate

Iron content in concentrate, mg / l

The residual concentration of nickel in the filtrate, mg / l

Consumption per 1 kg of nickel, kg

20 0.4

0,002

Claims (1)

METHOD FOR REMOVING NICKEL FROM RINSING WATERS OF ELECTRICAL PRODUCTION, including sorption of nickel from these waters, elution of nickel from a sorbent with a solution of sulfuric acid, washing of cation exchange resin with an alkali solution, characterized in that, in order to reduce the consumption of reagents and impurities in the filter, simplify the technology, sorption is carried out on phosphonic acid cation exchange resin, nickel is eluted with an equivalent amount of sulfuric acid absorbed by the metal, and after washing with alkali, the cation exchange resin is washed with neutral citrate Fern solution. 1.1187I7_