LIX 64N

LIX 64N Reagent is a water insoluble mixture of substituted oximes, which form water insoluble complexes with metallic cations, principally copper.

Chemical Reactions

LIX 64N Reagent is a hydrogen ion donor, and its chemical reactions when used as a copper extractant may be compared to an ion exchange resin system operating on a hydrogen ion cycle:

As would be expected from the above equation, the extraction of copper from dilute sulfuric acid solutions is pH dependent, and in most cases the extraction coefficient for copper falls below acceptable levels below an equilibrium pH of about 1.2.

Stripping may be accomplished by contacting the copper containing (loaded) organic with relatively strong sulfuric acid. In most cases, an excess acid concentration of 50 g/1 H2SO4 is required to maintain adequate stripping. Spent electrolyte (containing copper) may be used as the stripping agent, and the copper content can be increased to any desired level up to about 100 g/1 Cu for use as strong electrolyte. Electrowinning appears to be the most practical method for subsequent copper recovery.

Chemical and Physical Properties

All values approximate, and may vary slightly from lot to lot.

Solubility

LIX 64N Reagent has been tested at levels of 5, 10 and 25 percent in the following solvents, and found to be completely miscible in all cases except as noted:

Specifications

Not yet established. Manufacturers quality control based on maximum loading capacity and phase separation time requirements with the use of arbitrarily established standard solutions.

Availability

LIX64N Reagent is available in drum quantities (net 400 pounds), five-gallon pails (net 50 pounds) and one-gallon pails (net seven pounds), from our plant in Kankakee, Illinois. Multi-drum quantities to 10,000 pounds available for immediate shipment. Larger than 10,000 pound quantities may be subject to lead time delays, and agreement on a shipping date should be arranged with the manufacturer as far in advance as possible.

Toxicity

Acute toxicity studies were performed on LIX 64N Reagent for General Mills by the Industrial BioTest Laboratories in Northbrook, Illinois. The following results were reported:

Acute Dermal Toxicity (albino rabbits)…………………………………LD50> 10.2 g/kg
Eye Irritation Test (albino rabbits)………………………………………Mildly irritating
Primary Skin Irritation Test (albino rabbits)………………………..Moderately irritating

The complete report is available from General Mills on request.

Since kerosene is normally the diluent for LIX64N Reagent and kerosene is considered a primary skin irritant, normal precautions for handling kerosene should be applied to the mixed organic system. If additional information is desired, write General Mills for the report “Toxicological Review—Kerosene.”

Introduction

Alamine 336 is a water insoluble, symmetrical, straight chain, saturated tertiary amine. The alkyl groups are a C8-C10 mixture with the C8 carbon chain predominating.

Typical Analysis

Tertiary Amine Content……………………………95%
Secondary Amine Content…………………………1%
Primary Amine Content…………………………..0.2%
% Water…………………………………………………0.0%

A reagent grade of Alamine 336, Alamine 336-S, is available in commercial quantities. This product is 99-100% tertiary amine. The commercial price schedule for Alamine 336-S is available upon request.

Suggested Uses

1. Alamine 336 functions as a liquid ion exchange (LIX) reagent in the extraction and concentration of anions from aqueous acidic solutions. Alamine 336 forms metallic complex salts with many metals which are insoluble in water and soluble in organic solvents. Anionic species of the following metals are known examples:
   
   In addition, this reagent extracts both inorganic and organic acids from process and waste stream’s.
2. Corrosion inhibitor for organic systems
3. Additive for petroleum products
4. Chemical intermediate
5. Preparation of organometallic salts
6. Analytical reagent

Chemical Reactions

Alamine 336 is basic in nature and therefore forms amine salts upon reaction with inorganic and organic acids, e. g.:

The amine sulfate salt, like the free amine, is soluble in the organic phase but insoluble in the aqueous phase. This reaction demonstrates how the solubility characteristics and the chemical behavior are both utilized to extract acid constituents from an aqueous solution by amine neutralization.

The anions of the amine salts are capable of undergoing ion exchange reactions with other anions according to the following general reactions:

(A- and B- represent different anionic species)

The extent to which B is transferred to the organic phase by the ion exchange reaction with A- of the amine salt depends upon the relative affinity of these anions for the amine, and not solely upon the solubility of B- in the organic phase, as is the case in true solvent extraction processes.

Reaction 3 is an example of extraction by ion exchange.

It is imperative that the two phases be adequately mixed because the exchange of anions occurs at the interface of the two phases. Since the salts of Alamine 336 function as liquid ion exchange reagents, the choice of reagents is quite large.

An inorganic salt solution containing, for example, NaCl, Na2CO3, (NH4)2SO4 may be used as a stripping agent. It is necessary that the stipping solution be sufficiently alkaline or acidic to reverse the extraction reaction and simultaneously regenerate the organic extractant for recycle. Reaction 4 shows the stripping action of Na2CO3 on the amine uranyl sulfate complex.

In certain cases, the formation (and thus extraction) of anionic complexes is dependent on the concentration of the anion contributing to the anionic complex, as in the formation of CoCl x -y. Water may be used to strip complexes of this type.

Availability

Alamine 336 is available in tankcar and drum quantities, f. o.b. Kankakee, Illinois. Drum quantities are supplied in non-returnable, open head 55- gallon steel drums (I.C.C. 17-H), net weight 360 pounds per drum.

Toxicity

The fatty amines are organic bases and are therefore skin irritants. In the case of direct contact with the skin, it is recommended that the area be washed with dilute acetic acid (2-4%) or vinegar and then with copious quantities of soap and water. An amine “burn” is similar to an alkali burn.

Aliquat 336 is a water insoluble quaternary made by the methylation of a straight chain, saturated, symmetrical tertiary amine.

R is a mixture of C8 and C10 carbon chains, with the C8 predominating.

Suggested uses for Aliquat 336

1. Aliquat 336 functions as a liquid ion exchange (LIX) reagent in the extraction and concentration of anions from aqueous acidic and alkaline solutions. Aliquat 336 forms aqueous insoluble, organic soluble metallic complexes of many metals. Anionic species of the following metals are known examples:
   
2. Corrosion inhibitor for organic systems
3. Additive for petroleum products
4. Chemical intermediate
5. Preparation of organometallic salts

Aliquat 336

The application of Aliquat 336 as a liquid ion exchange reagent (No. 1 above) is dependent upon the exchange of the anion of the Aliquat 336, which is in the organic phase for the sought anion present in the aqueous phase. Therefore, for some LIX applications it may be desirable t0 convert the chloride form of the Aliquat 336 to other salt forms, e.g. sulfate, carbonate, acetate and others, to achieve faster and more complete exchange of anions between the two phases. The many possible salt forms of Aliquat 336 demonstrate the versatility of this LIX reagent as they provide a wide choice of LIX reagents to meet the specific requirements of a particular system. A description of a method for the conversion of Aliquat 336 to the sulfate form follows:

1. Dilute the Aliquat 336 to the desired concentration with an organic diluent, e.g., kerosene.
2. Contact equal volumes of the organic Aliquat 336 solution and 1.5 M H2SO4. Agitate for one minute.
3. Decant the aqueous phase and repeat Step 2 for a total of four contacts.

This procedure will result in complete conversion. If desired, the remaining chloride concentration may be checked by classical chloride determination procedures. Other salt forms of the Aliquat 336 may be obtained by a similar procedure, using the sodium salt of the anion.

Physical and Chemical Properties

Appearance

Aliquat 336 is an amber colored, viscous liquid at room temperatures.

Availability

Aliquat 336 is available in multi-drum quantities from our plant in Kankakee, Illinois. Orders, requests for samples, or further information, should be directed to:

General Mills, Inc.
Chemical Division
LIX® Reagents & Systems
2010 East Hennepin Ave.
Minneapolis, Minn. 55413

Preliminary test work has been completed on the two experimental extractants, XI-52 and XI-54. The preliminary tests included separatory funnel shake-out extraction and stripping isotherms at ambient temperature (-24 °C) and at elevated temperatures (40-50 °C). The aqueous solution used for testing contained the followings:

The organic diluent used in all tests was Escaid 100.

The data for the extraction isotherms are shown in Tables 1 and 2. The isotherms from both tables are shown in Figure 1. Several comparative points can be derived from the data:

1. XI-54 has a greater loading capacity.
2. Neither reagent loads Pb.
3. XI-54 gives the best recovery in an equal number of stages.
4. XI-54 loads a little more nickel and zinc than XI-52, but crowding or loading to maximum should be effective.
5. Heat in extraction seems to decrease loading capacity (by about 2-4%), but recovery is improved making the transfer about equal between hot and ambient systems.
6. Heat has little measurable effect extraction selectivity.

The data for stripping is shown in Table 3 and Figures 2 and 3. As above, comparable features can be found along with some questions. Both reagents can be stripped of copper in a minimum number of stages. However, the scattering of points for each curve suggests that percent stripping is a function of tha copper concentration in the aqueous electrolyte (and to a lesser extent free acid). Stripping isotherms are difficult to analyse, however, because of the organic: aqueous ratios used (no recycles to 1:1 mixing) and because the copper sulfate crystallized after contact (therefore the data in the tables for aqueous analyses were calculated). Further definitions of the stripping behavior should be made dynamically in the continuous laboratory circuit.

In summary, although both reagents look very good, XI-54 appears to be the best choice for most cases of copper ammonia leaching. In some or our tests we found that when XI-54 was loaded with nickel, the nickel-reagent complex precipitated. This was not found with XI-52. Further definitive tests are planned in this area as well as the use of aromatic diluents to keep the complex soluble.

Kinetic tests showed that 95-100% equilibrium was achieved in 30 seconds (for both reagents at both test temperatures). To date tests have not been run on loading capacity, percent recovery, and selectivity as a function of ammonia concentration in the leach liquor. These tests will be run in the future.

Based on the results of the preliminary tests, circuit evaluations should be initiated while using two extraction and two stripping stages. Preliminary data indicate the ammonia is not loaded or absorbed but might transfer by entrainment alone. So, although a wash stage might be required (between extraction and stripping), the cost of neutralization in the wash stage should be minimal compared to LIX® 64N and LIX® 65N. Phase separation is much better with XI-52 and XI-54 such that 100% commercial reagent could be recommended rather than putting a 40% limit on it as in common with LIX 64N and LIX 65N. This added feature should eliminate the need for any aqueous recycles in the extraction circuit and minimize the aqueous recycles in the strip circuit, thus providing a smaller circuit.

Due to the limited inventory of XI-52 and XI-54, samples cannot be issued for the present time.

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