KR100661812B1 - The preparation method of dithiapentamethylene diamine adsorbent for precious metals - Google Patents

Abstract

The present invention relates to a method for producing a dithiapentamethylene diamine adsorbent, and comprises reacting ammonium chloride, sodium sulfide and hydrochloric acid to produce NH ₄ HS, and reacting NH ₄ HS with formaldehyde.

Description

The preparation method of dithiapentamethylene diamine adsorbent for precious metals}

The present invention relates to a method for preparing a dithiapentamethylene diamine adsorbent used as a noble metal adsorbent. Specifically, the present invention is used to adsorb and extract precious metal ions such as gold, silver, platinum and platinum group metals from a solution containing various metal ions. It relates to a process for producing a dithiapentamethylene diamine adsorbent.

Conventionally, the noble metal adsorbent (trade name: SRAFION NMRR), which has been generally used, is yellow and has a isothiourea group as a copolymer of styrene and divinylbenzol (2%). This adsorbent exhibits selectivity for platinum group metals. Adsorption capacity in 0.05M HCl solution is as follows (g / g): Pt-0.488, Pd-0.218, Rh-0.190 and Ir-0.158 [A sorption concentrating platinum metals and gold in flowing systems of the analysis. L.V.Bagachyova, I.A.Kovalyov, etc 17 International Cheenyatv meeting in chemistry, the analysis and technologues of platinum metals, Moscow, on April 17-19, 2001].

However, this extraction method using conventional adsorbents has a lethal bond that there is a significant load on incineration of adsorbents after adsorption. Incineration of a large amount of adsorbent requires a lot of energy, and incineration of an electric furnace requires a high temperature of 870 ° C or higher.

Accordingly, the present inventors can incinerate at a relatively low temperature, thereby saving energy, and have excellent selectivity and adsorption capacity for noble metals, and particularly, dithiapentamethylene diamine as a noble metal adsorbent having excellent adsorption performance regardless of liquidity such as acid or alkali solution. Adsorbents have been developed.

However, in the conventional literature, dithiapentamethylene diamine (S ₂ N ₂ (CH ₂ ) ₅ ) has not been used as a noble metal adsorbent, and there is no publication about the preparation method thereof. Deliepin [Goerge Walker "Formaldehyde", the USSR, Moscow, the State chemical publishing house, 1957) has published a method for preparing pentamethylenediamine sulfide of the following structural formula.

In addition, K. Lefer and R. Lefer (Russian Patent No. 2160232 C1 (1999.7.14)) disclose a compound of the following structural formula which melts at 200 ° C., which can be prepared from ammonium sulfide and formaldehyde.

Jacobson produced an isomer product that melted at 183 ° C. of the same structure S ₂ N ₂ (CH ₂ ) ₅ from a 37% aqueous solution of formaldehyde, ammonium chloride, and sodium sulfide. The product can be easily removed from ethylenedichloride by fractional crystallization.

From the study of the state of aqueous formaldehyde solution, the aqueous aldehyde solution is the equilibrium of monohydrate CH _2- (OH) ₂ of methylene glycol, hydrated low molecular weight polymer or polyoxymethylene glycol of general formula HO- (CH ₂ O) H. It can be seen that it forms a mixture. The condition of equilibrium depends on the temperature and the content of formaldehyde in the solution. In a study by Goerge Walker "Formaldehyde", the USSR, Moscow, the State chemical publishing house, 1957, the equilibrium reaction at 30% formaldehyde concentration, 20 ° C, pH = 2.6-4.5 is as follows:

_{HOCH 2 OCH 2 OCH 2 OH ↔} CH 2 + OCH 2 OCH 2 O - + H + + OH -

It is therefore an object of the present invention to provide an optimal process for preparing dithiapentamethylene diamine (S ₂ N ₂ (CH ₂ ) ₅ ) adsorbents.

The object of the present invention is achieved by a process for producing a dithiapentamethylene diamine adsorbent consisting of reacting ammonium chloride, sodium sulfide and hydrochloric acid to produce NH ₄ HS and reacting NH ₄ HS with formaldehyde.

Hereinafter, the present invention will be described in detail.

1) Firstly, ammonium chloride, sodium sulfide and hydrochloric acid are reacted to obtain NH ₄ HS.

NH ₄ Cl + Na ₂ S + HCl = NH ₄ HS + 2 NaCl

2) Formaldehyde is added and reacted to obtain dithiapentamethylene diamine and water.

NH ₄ HS + 5 CH ₂ O = S ₂ N ₂ (CH ₂ ) ₅ + 5H ₂ O

The detailed mechanism of this reaction is as follows.

The aqueous NH ₄ HS solution produces ammonium hydroxide and hydrogen sulfide by reaction:

NH ₄ HS + H ₂ O = NH ₄ OH + H ₂ S

The resulting ammonium hydroxide reacts with formaldehyde to form methylolamine:

2NH ₄ HS + 2CH ₂ O = 2NH ₂ -CH ₂ -OH + H ₂ O

Methylolamine again condenses to form azomethine NH = CH ₂ which promotes ring linkage:

2NH ₂ -CH ₂ -OH = 2NH = CH ₂ + 2H ₂ O

The reaction of azomethine with formaldehyde leads to ring linkage.

Here, reaction with hydrogen sulfide, which was produced as a by-product from the first hydrolysis reaction, forms dithiapentamethylene diamine (S ₂ N ₂ (CH ₂ ) ₅ ):

The dithiapentamethylene diamine adsorbent produced by the production method of the present invention is stable even in strong acids and strong alkalis and does not decompose. One gram of adsorbent can adsorb about 0.55-1 grams of precious metal.

Example 1

153 g of Na ₂ S * H ₂ O (1 mol, Na ₂ S content 51%) was dissolved in 340 ml of water. 53.5 g (2 mol) of NH ₄ Cl was dissolved in 240 mL of water. 86 mL of HCl was added to the aqueous ammonium chloride solution. NH ₄ Cl + HCl aqueous solution was added to the Na ₂ S aqueous solution as a cooling stream. 214 g of aqueous formaldehyde solution was added to the resulting solution. The reaction was continued until aggregation of the adsorbent occurred. The product was left to solidify for 48 hours, filtered and dried at 70 ° C. for 24 hours. The adsorbent cured during drying. The dried adsorbent was milled and passed through a pole. 67 g of a pale yellowish white powder adsorbent was obtained. Yield 76%.

As can be seen above, NH ₄ HS is prepared by reacting ammonium chloride, sodium sulfide and hydrochloric acid by the method of the present invention, and NH ₄ HS is reacted with formaldehyde to prepare a dithiapentamethylene diamine adsorbent. Can be. The dithiapentamethylene diamine adsorbent prepared by the present invention is decomposed at a relatively low temperature as compared to the conventional adsorbent, so that it is very economical because it does not require much energy consumption to incinerate the adsorbent. In addition, the adsorbent of the present invention has a high selectivity for precious metals among the metal ions and shows an excellent adsorption capacity improved by about 20% or more compared to the conventional adsorbent.

In addition, the adsorbent of the present invention has a feature that can be used irrespective of the liquidity of a solution such as an acid or an alkali, particularly a strong acid or a strong alkali.

Claims (1)

Ammonium chloride and sodium sulfide hydrate, and hydrochloric acid 1: 1: 1 were reacted at a molar ratio of 1 producing the NH ₄ HS, and the NH ₄ HS formaldehyde and 1: 5: D is configured by reacting in a molar ratio of thiazol pentamethylene diamine Manufacturing method.