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金回收: 使用TULSION® 杜笙离子交换树脂从氰化物溶液中回收金.
Gold Recovery : From cyanide liquor USING TULSION® ION EXCHANGE RESIN.
简介/ INTRODUCTION :
传统上使用活性碳吸附金子。珍贵的金会被活性碳吸附于表面,再藉由洗涤或直接焚烧以回收金。
Conventionally activated carbon is used for extracting the gold from the mother liquor commonly contacted with beds of activated-carbon. The precious noble metal loaded on the activated carbon is recovered by elution or simply by incineration of the carrier at high temperature.
使用离子交换树脂回收贵金属比活性碳还具有多方面的优势, 因为藉由特殊制造过程中, 我们可以在其结构上的有效官能基上置入具有选择性的离子,以选择性的吸附此贵重金属。
Ion exchange resins are more versatile substrates than activated carbons can be used, because specific functional groups can be afixed on the resin matrix, for better selectivity, during the synthesis. These resin can be tailor-made to improve the gold carrier features such as selectivity, resistance to poisoning by calcium or organic materials and loading capacity.
因此, 由于具有经济考虑优势, 离子交换树脂普遍被使用于贵金属回收。而大部份使用阴离子交换树脂来交换吸附贵金属。
Therefore the ion exchange resins are economically adopted for the gold recovery. Mostly Anionic type of ion exchange resin are used that adsorb the gold.
用氰化物萃取金的过程中, 金会以阴离子的氰化金型式存在, 既Au(CN)2- ; 再经由强碱或弱碱的阴离子交换树脂交换回收。如Tulsion®A-23（强碱）,Tulsion®A-27mp（强碱）及Tulsion®A-2X mp (弱碱) 。
The gold extracted by cyanidation is in the form of anionic aurocyanide complex Au(CN)2 - and can be recovered from the pregnant solution by ionic exchange with strong or weak base anion exchange resin ,such as Tulsion®A-23,Tulsion® A-27MP and Tulsion®A-2XMP
(a) 强碱离子交换树脂方面的应用:
此型的强碱型阴离子树脂具有四级铵的官能基,在高pH 值的溶液中,藉由交换氯离子的相反离子来吸附Au(CN)2
- ; 其反应机构如下:
(a) STRONG BASE ANION:
These resins contain quaternary ammonium functionality which, when contacted with the high pH leachate stream, adsorb the aurocyanide anion via exchange for the resin's chloride counter-ion:
XxxNR3 *X + Au(CN)2 xxx NR3 * Au(CN)2 + X
再藉由更强的阴离子树脂或是用其它的化学反应, 将吸附的金洗涤出。通常最经济实惠的替代反应是用氰化锌或是用硫代氰酸盐将金洗出, 如下:
Elution of the adsorbed gold complex can be accomplished by displacement with a more strongly adsorbed anion or by chemical reaction. Competitive displacement is typically done with either zinc cyanide or thiocyanate:
XxxNR3*Au(CN)2 + SCN+ xxxNR3*SCN + Au(CN)2
XxxNR3*Au(CN)2 + Zn(CN)42+ [xxxNR3*]2 Zn(CN)4 + 2 Au(CN)2
不管以上是用何种方法洗涤出金错化物,此强酸型阴离子树脂最终都必须用硫酸或硫酸铁将其转换回硫酸盐型式,以利下一次的金吸附的反应机构模式。其回复的反应机构如下:
In either case, the resin must then be converted back to the sulfate form prior to return to adsorption service, typically with sulfuric acid or ferric sulfate. however, the preferred method of elution is by chemical reaction with thiourea:
XxxNR3*Au(CN)2 + SC(NH2)2 + 2H2SO4 xxxNR3*HSO4 + 2 HCN
+ [ Au {SC(NH2)2}2] + HSO4-
b) 弱碱型阴离子交换树脂的应用:
另一种是用弱碱型的阴离子交换树脂。由于此弱碱型的阴离子树脂都是以自由基型式存在, 所以必须先用酸处理之后, 再用来吸附金。其反应机构如下:
b) WEAK BASE ANION:
An alternative approach to the above is the use of weak base anion exchange resins which, because they are normally supplied in the "free base" form, need to be treated with acid prior to contact with the leachate stream. A typical cycle is conceptually as follows:
XxxNR2 + HX xxxNR2H*X-.
XxxNR2 H+X + Au(CN)2 XxxNR2 H+Au(CN)2 +XXxxNR2
H+Au(CN)2 + NaOH XxxNR2 + Na+Au(CN)2 + H2O
因为弱碱型阴离子的高交换容量及可以得到较高的处理量, 于小型的操作系统模式, 通常都会用焚烧来取代洗涤的方式来回收金。
Because of the high capacity available with ion exchange resins and the high loading that can therefore be obtained, in most small scale operations it is often an option to consider incineration of the loaded resin rather than elution.
通常弱碱型阴离子交换树脂最被常用于此贵金属回收。
Commonly the Weak base anion ion exchange resins are used for this application
建议杜笙/ Tulsion®离子交换树脂型号:
RECCOMENDED TULSION PRODUCT :
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产品/ PRODUCT 型式/ TYPE
Tulsion® A-23 AU 强碱凝胶型阴离子具有四级铵官能基
A strong base gel-type resin containing quaternary-amine functional groups
Tulsion® A-27MP 强碱巨孔型阴离子具有四级铵官能基
A strong base macro porous resin containing quaternary-amine functional groups
Tulsion® A-2XMP S 弱碱巨孔型阴离子具有四级铵官能基
A weak base macro porous resin containing tertiary amine functional group