Processes for removing hydrazine from hydroxylamine solutions
AssigneeCytec Technology Corp.
InventorsMorris LEWELLYN, Alan S. ROTHENBERG, Haunn-Lin Tony CHEN, Lino G. MAGLIOCCO, Thomas P. SASSI
Life of this patent
Estimating the term…
Abstract
The present invention relates to processes for reducing or eliminating the amount of hydrazine from a hydroxylamine-free base containing hydrazine by treating said hydroxylamine-free base with a scavenger agent, and to the hydroxylamine-free base thereby obtained, as well as to its use for producing microdispersions containing a hydroxamated polymer for use as a flocculant in the Bayer process.
Claims16
A process for reducing the amount of hydrazine from a hydroxylamine-free base containing hydrazine, the method comprising treating said hydroxylamine-free base with a scavenger agent selected from compounds of formula I and/or II
- wherein
- each of X1 and X2 is individually chosen from:
- H, OH, NR″2, OR′″, SH, halide or an optionally substituted hydrocarbyl group, with the proviso that not both of X1 and X2 are OH groups, wherein each R″ is independently chosen from:
- H or an optionally substituted hydrocarbyl group;
- R′″ is an optionally substituted hydrocarbyl group wherein two R′″ groups can also form an optionally substituted ring system;
- or R′″ is an alkali metal or NRV4, wherein each RV is independently chosen from:
- H or an optionally substituted hydrocarbyl group;
- X3 is chosen from:
- O, NR′, S, or PR′, wherein R′ is chosen from:
- H, OH, alkali metal, NRIV2 or alkyl, wherein each RIV is independently chosen from:
- H or an optionally substituted hydrocarbyl group;
- R is chosen from:
- CR1R2 where each of R1 and R2 is independently chosen from:
- H or an optionally substituted hydrocarbyl group, wherein R1 and R2 together can also form an optionally substituted ring;
- R3C═CR4 where R3 and R4 together form an optionally substituted ring;
- and
- R5R6C—CR7R8 where R5 and R7 together form an optionally substituted ring, and wherein each of R6 and R8 is independently chosen from:
- H, or an optionally substituted hydrocarbyl group,
- with the proviso that R1 can form a ring system with X1.
A hydroxylamine-free base solution containing less than 500 ppm of hydrazine based on hydroxylamine-free base and which contains less than 1 equivalent weight of by-product salt per equivalent of hydroxylamine.
A hydroxamated vinyl polymer water-in-oil microdispersion comprising at least one hydroxamated vinyl polymer and less than 1 equivalent of by-product salt per equivalent of hydroxamate group present on the polymer.
A hydroxamated vinyl polymer water-in-oil microdispersion comprising at least 18% by weight of polymer calculated on the basis of the vinyl polymer before hydroxamation.
Dependencies are inferred from the claim text.