JP2002224501A - Method for recovering organic solvent bis(2-butoxyethyl) ether - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for simply and efficiently recovering bis(2- butoxyethyl)ether (hereinbelow, referred to as DBC(dibutyl carbitol)) being an organic solvent for extracting gold from an aqueous solution while reducing equipment cost or running cost. SOLUTION: An aqueous solution wherein DBC is suspended or dissolved is mixed with a non-polar organic solvent to extract DBC by the non-polar organic solvent and the non-polar organic solvent having extracted DBC is subjected to back extraction using hydrochloric acid and this hydrochloric acid is diluted with water to liberate and precipitate DBC to recover the same as oil drops. As the non-polar organic solvent to be used, hydrocarbon liquid at the normal temperature is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of recovering bis (2-butoxyethyl) ether (hereinafter referred to as DBC) as an organic solvent for gold extraction from an aqueous solution, and more particularly to a method for recovering gold from a chlorine leaching solution of copper electrolytic slime. The present invention relates to a method for recovering DBC from an aqueous solution containing DBC generated in the recovery step of (1).

[0002]

2. Description of the Related Art In a process of recovering gold from a chlorine leaching solution of copper electrolytic slime, DBC is mixed with a chlorine leaching solution of copper electrolytic slime as described in JP-A-9-316561 and Japanese Patent No. 3087758. Thus, gold is extracted, and this gold-containing DBC is washed with hydrochloric acid, and then reduced to recover gold as a simple substance.

[0003] In this gold recovery step, an aqueous solution in which DBC is suspended or dissolved, such as a raffinate, is generated.
It is necessary to recover DBC from this aqueous solution. DBC is easy to dissolve in water or aqueous solution.
Since / l also dissolves, it is desirable to recover DBC by a process in which DBC is brought into contact with water in consideration of economy.

A method of recovering DBC which has been conventionally used is described in J. A. E. FIG. Hoffmanet al., “HY
DROMETALLURGY '94 ”, CHAPMA
N & HALL (1994) 69; Fetter.
K. C. Sole et al., "Js Afr. In
st. Miningand Metall ”, (199
7) As described in 169, a distillation method of recovering DBC by heating an aqueous solution containing DBC and cooling the vapor of an azeotropic mixture of water and DBC is common.

[0005]

However, the above-mentioned method of recovering DBC by the distillation method requires a large-scale facility, requires a large installation area, requires a large facility cost, and has a particularly large amount of gold. When an acidic liquid such as a liquid is handled, special materials are required, so that the equipment cost is further increased.

Further, the distillation method has a problem that the running cost is high due to the large energy consumption, and the economical efficiency is impaired when a small amount of organic solvent is to be recovered. Further, by heating and concentrating the solution, crystals and precipitates are easily formed, which causes a trouble that the piping of the device is blocked.

The present invention has been made in view of such a conventional situation,
It is an object of the present invention to provide a method for simply and continuously recovering DBC, which is an organic solvent for gold extraction, from an aqueous solution while reducing equipment costs and running costs.

[0008]

In order to achieve the above object, the present invention provides a method for recovering an organic solvent bis (2-butoxyethyl) ether by suspending or dissolving bis (2-butoxyethyl) ether. The bis (2-butoxyethyl) ether is extracted into the non-polar organic solvent by mixing the aqueous solution with the non-polar organic solvent, and the non-polar organic solvent from which the bis (2-butoxyethyl) ether is extracted is reversed with hydrochloric acid. Bis (2-butoxyethyl) ether is recovered in hydrochloric acid by extraction.

In the method of recovering the organic solvent bis (2-butoxyethyl) ether of the present invention, the non-polar organic solvent is a liquid hydrocarbon at ordinary temperature. Further, in the method for recovering the organic solvent bis (2-butoxyethyl) ether of the present invention, the bis (2-butoxyethyl) ether containing the back-extracted bis (2-butoxyethyl) ether is diluted with water to obtain the bis (2-butoxyethyl) ether. (Ethyl) ether is separated out and separated and collected as oil droplets.

[0010]

DETAILED DESCRIPTION OF THE INVENTION In general, organic solvents have different solubility in water depending on their molecular structure, types of functional groups, etc. In the case of non-polar organic solvents which do not completely dissolve in water, they are more hydrophilic than organic solvents. Lipophilicity is prevailing. Therefore, when an aqueous solution in which a certain organic solvent A is dissolved and a non-polar organic solvent B that does not completely dissolve in water are mixed, the organic solvent A in the aqueous solution is extracted into the non-polar organic solvent B. Further, the extraction ratio of the organic solvent A from the aqueous solution to the non-polar organic solvent B changes depending on the salt concentration, the acid concentration, and the like in the aqueous solution.

[0011] In the case of bis (2-butoxyethyl) ether (DBC) as an organic solvent, when the acid concentration in an aqueous solution containing DBC, particularly hydrochloric acid concentration, increases, the extraction rate of DBC into a non-polar organic solvent is greatly reduced. I understood that. The method of the present invention applies this principle by extracting DBC in an aqueous solution having a low free hydrochloric acid concentration with a nonpolar organic solvent, and thereafter mixing the nonpolar organic solvent from which the DBC has been extracted with an aqueous solution having a high free hydrochloric acid concentration. Recovers DBC from a non-polar organic solvent into an aqueous solution.

Next, the method of the present invention will be described in detail step by step. The aqueous solution in which DBC is suspended or dissolved is typically used in a step of recovering gold from a chlorine leaching solution of copper electrolytic slime, a raffinate in which gold is extracted by DBC, or a hydrochloric acid of DBC containing extracted gold. It is calculated as a cleaning liquid.

[0013] DBC is soluble in water like other organic solvents, but the solubility decreases as the acid concentration in the water decreases.
However, even if the acid concentration is reduced as much as possible, the solubility of DBC in water is reduced to a practical level of 0.0 ng / l order,
That is, it is difficult to reduce the amount to 0.1 g / l or less.

In the method of the present invention, first, an aqueous solution containing DBC having a reduced hydrochloric acid concentration is mixed with a non-polar organic solvent, whereby DBC in the aqueous solution is extracted into the non-polar organic solvent, and is easily extracted. Dissolve the amount of DBC in the aqueous solution to 0.3.
It can be reduced to the order of 0 ng / l or less. As for the mixing ratio between the aqueous solution containing DBC and the non-polar organic solvent, if the phase ratio O / A is 1/50 or more, the amount of DBC dissolved in the aqueous solution can be reduced to the order of 0.0 ng / l by extraction. it can.

The nonpolar organic solvent used for extracting DBC can be used without any particular limitation as long as it is hardly soluble in water. However, hydrocarbons are preferable in consideration of the water solubility of the nonpolar organic solvent itself. Considering the risk of loss due to volatilization and the danger of ignition, third petroleum hydrocarbons such as kerosene are more preferred. An aromatic hydrocarbon has a higher extraction ratio of DBC from an aqueous solution than an aliphatic hydrocarbon, but on the contrary, the reverse extraction of DBC into an aqueous solution tends to be worse.

Next, DB extracted in a non-polar organic solvent
C is back-extracted with hydrochloric acid. The higher the concentration of hydrochloric acid in the aqueous solution for back-extracting DBC, the higher the back-extraction rate. However, when the concentration of hydrochloric acid is 7 mol / l or less, the back-extraction becomes incomplete, and therefore the concentration is preferably 8 mol / l or more. The mixing ratio of the nonpolar organic solvent from which DBC is extracted and hydrochloric acid is preferably a phase ratio O / A = 1/1 or less.

The raffinate after the extraction of DBC into the non-polar organic solvent by the method of the present invention is supplied to the step of recovering the valuable metals contained therein. In addition, D obtained by back extraction
The hydrochloric acid containing BC can be used as it is or diluted with water, and can be used as a hydrochloric acid cleaning solution for DBC containing extracted gold by repeating the process of extracting gold from the chlorine leaching solution of copper electrolytic slime.

Furthermore, the hydrochloric acid from which DBC has been recovered by the method of the present invention is diluted with water to lower the concentration of hydrochloric acid in the aqueous solution, thereby lowering the solubility of DBC and causing DBC to separate out as oil droplets. It is also possible to separate and collect DBC. The aqueous solution having a low hydrochloric acid concentration after separating and recovering DBC can be repeatedly used as diluted hydrochloric acid used in a step of extracting gold from a chlorine leaching solution of copper electrolytic slime.

In the present invention, the organic solvent to be recovered is DB
Although the method is limited to C, it goes without saying that the method of the present invention can be applied to other organic solvents that are hardly soluble in water but easily soluble in hydrochloric acid.

[0020]

【Example】Example 1  Gold raffinate containing 1.4 g / l DBC (copper electrolytic slime
Raffinate extract of gold from DB leachate by DBC) 200
20 liters of kerosene and 250 liters of kerosene
Place in a tank and stir for 15 minutes with a stirrer.
The DBC dissolved and suspended in the gold raffinate in kerosene
Extracted. After that, stop stirring and let stand for 30 minutes.
Oil-water separation was performed.

Only the aqueous phase (gold raffinate) was extracted from the bottom of the tank, and 200 liters of gold raffinate containing 1.4 g / l DBC was newly added to the remaining kerosene, followed by stirring for 15 minutes. Was performed. When this operation was repeated seven times, the DBC concentration in kerosene was 97 g / l, and 98.8% of DBC in the gold raffinate could be recovered.

Next, 20 liters of kerosene from which DBC was extracted and 20 liters of concentrated hydrochloric acid were stirred and mixed by a stirrer for 10 minutes, and only the aqueous phase was extracted. Then, 20 liters of concentrated hydrochloric acid was newly added and stirred and mixed for 10 minutes. . By repeating this operation three times, 91% of DBC was back-extracted into concentrated hydrochloric acid.

The hydrochloric acid in which DBC obtained by back extraction is suspended is diluted with water so that the hydrochloric acid concentration becomes 1.5 mol / l, and is used as a washing liquid for the organic phase of gold extraction in the gold solvent extraction step. And the DBC suspended or dissolved in the raffinate
90% or more could be repeated in the system.

[0024]Example 2  The composition of the used gold raffinate and the washing solution of the extracted organic phase is shown in Table 1 below.
Shown in This gold raffinate is DB in 11,570 liters
9.17 kg of C are dissolved and 4.64 kg are suspended. Ma
In addition, the washing liquid was used to convert DBC to 4.12k in 3,227 liters.
g dissolved and 1.17 kg suspended.

[0025]

[Table 1]

The raffinate solution and the washing solution are fractionated, and an alkylnaphthalene-based solvent (Exxon Chemical Co., Ltd.) is used as a non-polar organic solvent.
DBC was extracted using 60 liters (trade name: “Solvesse 200” manufactured by K.K.). The extraction was performed using a mixer settler while stirring and mixing in one stage of extraction, while Solvesso 200: raffinate = 1: 50, and Solvesso 20
The cleaning was performed at a flow rate of 0: washing liquid = 1: 50. D extracted
The non-polar organic solvent containing BC (Solvesso 200) was continuously stirred and mixed in two stages using the same mixer settler in the organic phase / water phase countercurrent, and the DBC was back-extracted with concentrated hydrochloric acid.

In the above extraction step, the gold extraction residue 1,1570
13.52 kg of DBC was extracted from 1 liter, and 5.12 kg of DBC was extracted from 3,227 liters of the washing solution. In the back extraction step with concentrated hydrochloric acid, 2.3.
kg of DBC was distributed in concentrated hydrochloric acid.

The hydrochloric acid in which DBC produced by the back extraction was suspended was diluted with pure water so that the hydrochloric acid concentration became 1.5 mol / l, and was repeatedly used in the process as a washing liquid of the gold extracted organic. As described above, when an aromatic solvent is used, extraction of DBC is easy, but there is a tendency that back extraction is slightly difficult.

[0029]

According to the present invention, DBC, which is an organic solvent for gold extraction, can be converted from an aqueous solution containing DBC generated in a step of recovering gold from a chlorine leaching solution of copper electrolytic slime with a small equipment cost and a running cost. It can be collected easily and continuously.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D056 AB17 AC02 BA04 CA06 CA14 CA17 CA20 CA26 CA28 DA03 4H006 AA02 AD16 BB11 BB31 BB43 BB44 BC33 BC37 BE01 GP01 4K001 AA04 DB28

Claims (6)

[Claims] An aqueous solution in which bis (2-butoxyethyl) ether is suspended or dissolved is mixed with a nonpolar organic solvent to extract the bis (2-butoxyethyl) ether into the nonpolar organic solvent. Then, the non-polar organic solvent from which bis (2-butoxyethyl) ether has been extracted is back-extracted with hydrochloric acid, whereby bis (2-butoxyethyl) ether is recovered in hydrochloric acid.
-Butoxyethyl) ether recovery method. 2. The method for recovering bis (2-butoxyethyl) ether as claimed in claim 1, wherein the non-polar organic solvent is a hydrocarbon that is liquid at room temperature. 3. An aqueous solution in which the bis (2-butoxyethyl) ether is suspended or dissolved and a nonpolar organic solvent are mixed at a phase ratio of O / A = 1/50 or more. The method for recovering the organic solvent bis (2-butoxyethyl) ether according to claim 1 or 2. 4. A method according to claim 1, wherein the non-polar organic solvent from which the bis (2-butoxyethyl) ether is extracted and hydrochloric acid are mixed in a phase ratio O / A =
4. Mixing at a ratio of 1/1 or less.
4. The method for recovering the organic solvent bis (2-butoxyethyl) ether according to any one of the above. 5. The concentration of hydrochloric acid used for back extraction is 8 mol / l.
The method for recovering an organic solvent bis (2-butoxyethyl) ether according to any one of claims 1 to 4, wherein 6. Diluting the back-extracted hydrochloric acid containing bis (2-butoxyethyl) ether with water,
Bis (2-butoxyethyl) ether is precipitated by free separation,
The liquid is separated and collected as oil droplets,
5. The method for recovering the organic solvent bis (2-butoxyethyl) ether according to any one of 5.