Process for making glycol ether compositions useful for metal recovery
View Patent ↗Glycol ether compositions useful for metal recovery by froth flotation and processes for making the compositions are disclosed. In one process, dipropylene glycol methyl ether (DPM) is propoxylated to give a composition comprising 4 to 15 wt. % of DPM and at least 20 wt. % of tripropylene glycol methyl ether (TPM). In another process, the glycol ether composition is made from a distillation residue which comprises DPM, TPM, and a basic catalyst. Extraction of the residue with water to remove some of the basic catalyst is followed by propoxylated to give a composition which comprises less than 15 wt. % of DPM, at least 20 wt. % of TPM, and one or more PO-based glycols. In comparative froth tests, glycol ether compositions of the invention meet or exceed the performance of commercial frothers.
1. A process which comprises:
(a) extracting a distillation residue comprising DPM, TPM, and at least 5 wt. % of a basic catalyst with water under conditions effective to provide an extracted residue comprising DPM, TPM, less than 15 wt. % of water, and less than 1 wt. % of the basic catalyst; and
(b) reacting the extracted residue from step (a) with propylene oxide in an amount effective to produce a glycol ether composition comprising 4 to 15 wt. % of DPM, at least 20 wt. % of TPM, and one or more PO-based glycols.
2. The process of claim 1 wherein the PO-based glycols are selected from the group consisting of propylene glycol, dipropylene glycol, tripropylene glycol, and mixtures thereof.
3. The process of claim 1 , wherein the DPM comprises one or more isomers.
4. The process of claim 1 , wherein the DPM comprises ARCOSOLV® DPM.
5. The process of claim 1 , wherein the basic catalyst comprises a catalyst selected from a group consisting of alkali metals, alkali metal hydroxides, alkali metal alkoxides, and double metal cyanide catalysts.
6. The process of claim 1 , further comprising removing the basic catalyst prior to the extracting.
7. The process of claim 1 , further comprising removing the basic catalyst, prior to the extracting, by water washing.
8. The process of claim 1 , wherein the reacting comprises a temperature within a range of 50° C. and 200° C.
9. The process of claim 1 , wherein the glycol ether composition is a frother.