New Products, Chelating, and Selective Resins

Chelating / selective resins contain specially oriented ionic and non-ionic groups that selectively capture specific ions from complex mixtures. The wide variety of available mechanisms allow for the development of new commercial separations and processes. DOWEX™ chelating resins are capable of high selectivity, making them suitable for tough jobs while lowering operating costs.

Dow is deeply committed to the development of new types of selective separations media which are commercially important. Below is a partial listing of Dow's developmental products and experimental projects.

DOWEX M-4195 Chelating Resin: Today, DOWEX M4195 chelating resin is used to facilitate the difficult separation of nickel from cobalt in cobalt refining facilities at INCO in Port Colbourne, Ontario, and Anglo Vaal's new state-of-the-art Chambishi Metals Plc, cobalt refinery in Zambia, Africa. Chambishi Metals Plc will process their slag dump over the next 30 years with the new $100 million cobalt plant. Chambishi metals will produce between 2,000 and 4,000 tons of cobalt and more than 5,000 tons of copper a year from the slag dumps. See the references below for details on the separation of nickel from cobalt refining streams.

DOWEX M4195 chelating resin is uniquely suited for recovering nickel from very acidic process streams. Several proprietary nickel-processing techniques are under development and are expected to have significant impact on the nickel mining industry.

Nitrate Selective Resins: Dow offers a triethylamine based nitrate selective resin, the DOWEX NSR-1 resin. DOWEX NSR-1 resin offers better selectivity for NO₃^- over other anions like SO₄⁼ and Cl^-. Nitrate selective resin gives better operating capacities for NO₃^- than either Type I or II anion resins. DOWEX NSR-1 resin meets the NSF / ANSI Standard 61.

Boron Selective Resin: Boron selective resin (BSR) is a weakly basic anion exchange resin having n-methyl-D-glucamine funtional group which is extremely selective for boron via a chelation-like mechanism. This chemistry is based on the cis-diol group, which will bind the boron in a five membered borate ester ring complex as illustrated in Figure 1, depicting Dow's styrenic boron selective resin, DOWEX BSR-1. The resulting boron complex is fairly stable and can bind and hold boron at very low concentrations, even in the presence of other ions. The complex can be broken and the resin regenerated by displacing the borate with either hydrochloric (HCl) or sulfuric (H₂SO₄) acid, water rinse, and then converting the resin back to the free base form by washing with sodium hydroxide (NaOH), followed by water washing to an application appropriate pH. The resin is regenerable and can be useful for several hundred process cycles, depending upon the quality of the incoming feed waters.

Of the various commercially available boron selective resins on the market today, DOWEX BSR-1 is the only one to currently carry the NSF / ANSI Standard 61 certification (Drinking Water System Components). DOWEX BSR-1 is a uniform particle sized resin as shown in Figure 2, with a particle size of 550+/-50 microns. The uniformity of this resin offers both faster uptake and elution kinetics for boron.

Figure 1	Figure 2

XZ-91419 Gold Selective Resins: Gold recovery from mining cyanidation leach solutions with anion exchange resins has long been common practice in the gold mines of the former Soviet Union (FSU). Today Western mining companies are discovering the economic benefits of gold recovery via ion exchange

Dow produces a gold selective resin, specifically designed from use in Resin-in-pulp and Pump-cell processing. The resin is XZ 91419.00** developmental resin, manufactured under exclusive license from South Africa's premier mining technology house, MINTEK. New process development using XZ 91419.00 can be fully supported through contractual arrangement with MINTEK's expert technical staff. For information on who to contact about the use of XZ 91419.00 in gold mining applications, e-mail Dr. Charles Marston at cmarston@dow.com.

Chloromethylated Copolymers: Dow's wide variety of copolymer beads are the building blocks for all of our separation media. A common way to activate styrenic copolymers is through chloromethylation where a CH₂Cl group is attached to the benzylic ring structure. Nucleophylic groups can be attached to the plastic backbone to create entirely new classes of separations media or catalysts. Dow offers a 2% gel, chloromethalyted resin for your development needs.

Acid regenerable copper chelating resin - Because of Dow's keen interest in mining applications, we have modified the chemistry of DOWEX M-4195 resin, making a new chelating resin that retains a high copper selectivity, yet allows for acid elution of the copper from the resin. New low cost copper recovery processes are envisioned and currently under pilot testing. An early version of this resin, which can be found in trade literature, is referred to as XFS-43084 or DOW 2N.

We Welcome New Interests: If you have a commerical separation opportunity and would like to discuss your needs with our staff of experts, please use our Feedback Form.

DOWEX Chelating Resins

Product	Description	Type	Matrix	Total Exchange Capacity* eq/l (kgr/ft3)	Available Forms
DOWEX M4195	Chelating resin for copper, nickel, and cobalt processing.	Chelating Resin	Styrene-DVB, Macroporous		Bis-Picolylamine
DOWEX NSR-1	A strong base, nitrate selective, anion exchange resin.	Triethylamine Strong Base Anion	Styrene-DVB, Macroporous	0.9 (19.7)	Cl-
DOWEX RSC	Highly selective for removal of radium and barium from water.	Barium Doped	Styrene-DVB, Gel	.65 meq/mL	H+
XUS 43578.00	Chelating resin for copper, nickel, and cobalt processing.	Chelating Resin	Styrene-DVB, Macroporous		Bis-Picolylamine
XZ 91419.00**	A large bead, gold selective strong base anion exchange resin for the recovery of gold from cyanidation leach solutions (manufactured under license from MINTEK)	t-Butylamine	Styrene-DVB, Gel	0.23 - 0.33 eq/l	Cl-