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The work outlined in this thesis was sponsored, in part, by Anglo American and concerns the development of new technologies to achieve the concentration and separation of base metal values in chloride hydrometallurgical circuits. New processes for the production of zinc, cobalt and nickel aim to use solvent extraction to achieve the separation of metal values in highly concentrated acid chloride feeds containing iron and this thesis involves new extractants for potential use in these circuits. Anion exchange solvent extraction was chosen as the most practical approach and so a range of new reagents are described which remove zinc(II), cobalt(II) and iron(III) chlorometallates from acid chloride solutions via the reaction: nL(org) + nH+ + MClx n- [(LH)nMClx](org) Chapter 1 reviews the literature which concerns base metal chloride hydrometallurgy, presents a range of commercial processes and discusses the chemistry which underpins them. This chapter also outlines the new Anglo American circuits and the general approach to the design of base metal chlorometallate extractants. In Chapter 2, the analytical methods are discussed. These methods include the solvent extraction experiments that were used to define the behaviour of the new ligands and the techniques that were employed to examine the interactions between an extractant and a chlorometallate anion. Chapter 3 presents a series of five new amido-functionalised pyridine reagents that were designed to investigate the affect of hydrogen bond donor functionality on the extraction of zinc, cobalt and iron chlorometallates. The pyridine nitrogen atom is sterically hindered in the new reagents to suppress formation of inner-sphere complexes. Solvent extraction performance was found to vary considerably with hydrogen bond donor functionality and ligand structure. The ligand 2-(4,6-di-tertbutylpyridin- 2-yl)-N,N’-dihexylmalonamide (L2) was the strongest and most efficient extractant in this series and this was attributed to a ‘proton chelate’ six-membered ring interaction between the malonamide oxygens and the protonated pyridine nitrogen that resulted in a pre-organised array of N-H and C-H donors that could interact favourably with the chlorometallate anion. Chapter 4 explores a series of six new tertiary amine-based ligands which contain varying amido-functionality, e.g. 3-(di-2-ethylhexylamino)-N-hexylpropanamide (MAA). Zinc, cobalt and iron chlorometallate extraction studies show the amide and malonamide-functionalised ligands are notably stronger than the tertiary alkylamine control, tris-2-ethylhexylamine (TEHA). Platinum(IV) extraction is also discussed, showing that some of the new reagents are more efficient than the tren-based ligands previously described,{Bell Katherine, 2008 #93} which were the most efficient known. The enhanced extraction performance of the new ‘MAA-type’ ligands was again attributed to the formation of a ‘proton chelate’ six-membered ring forming [(LH)2MCl4] assemblies in the organic phase. Conditions have been identified which would allow separation of Fe(III), Co(II) and Zn(II) in circuits which use the ‘MAAtype’ reagents. Chapter 5 explores a series of three new malonamide reagents which contain varying alkyl-chain functionality, e.g. N,N’-dimethylhexylpentadecylmalonamide (M1), which are thought to extract chlorometallate anions via protonation of the carbonyl oxygens. Zinc, cobalt and iron chlorometallate extraction studies demonstrate that the malonamide ligands show high efficiency and selectivity for iron over zinc and cobalt. Performance as chlorometallate extractants was found to vary considerably with ligand structure and hydrogen bond donor functionality in all three ligand series, with a number of ligands showing potential for commercial application. Analysis of anion-host interactions suggests that chlorometallate binding in the organic phase probably proceeds via an array of both N-H and C-H weak hydrogen bonding interactions between the extractant and the outer-sphere of the metallate complex.

The use of a new styrene-divinylbenzene copolymer bead, Showdex Polymerpak D-814, as a stationary phase in high-performance liquid chromatography is investigated. Unlike conventional silica-based stationary phases, copolymer beads may be used with both aqueous and organic mobile phases. The effect of the mobile phase on solute retention with the copolymer beads is described. Although the copolymer beads exhibit characteristics of both solid and liquid stationary phases, it is shown that the beads act primarily as a liquid when used with the mobile phases chosen for this work. It is further shown that solute retention on the beads results from dispersion interactions between the solute and the stationary phase. Batch extraction distribution constants are determined to confirm the validity of the distribution model proposed. The chromatographic behavior of a variety of aromatic compounds is described. These range from polycyclic aromatic hydrocarbons to substituted benzenes to phthalate esters. A quantitative measure of the effect of a substituent group on retention is developed from an analysis of the experimental results. This measure is then used to successfully predict the retention behavior of some disubstituted benzene compounds. Some model separations are developed to illustrate the usefulness of this measure. Finally, the implications of this work for gradient elution chromatography are discussed.

A high speed stirring apparatus was constructed for following the kinetics of metal ion extraction by chelating agents. The semi-automated system is capable of measuring reactions with half lives of 20 seconds or more with data being collected every second. Experimental data obtained with the device are superior to those collected by batch shakers, fixed interface cells, falling drop, or other stirring devices. The use of a microporous Teflon membrane phase separator along with the thermodynamic relation, the Gibbs Equation, enabled the measurement of drop sizes in a two phase liquid-liquid dispersion. This allowed the determination of the quantity of interfacial area as a function of stir rate. The effect of interfacial area on the rate of extraction of five different chelating agents with various divalent metal ions was determined in this study. The role of the interfacial area in extraction kinetics was found in a system where diffusional effects are negligible. This information provides an answer to the question of whether the rate determining step of extraction occurs in either the bulk aqueous phase or in the interfacial region. The proportionality between rate and specific interfacial area was employed to find the magnitude of the contributions of the bulk and interfacial components and also allowed the calculation of the individual rate constants. Evaluation of the bulk and interfacial rate constants yields important fundamental information as to the chemical nature and differences between the chloroform/water interface and the bulk aqueous phase. The results appear to illustrate that the interface is a more conducive medium for reaction between metal and ligand than the aqueous phase. The role of foreign species, namely nonionic surfactants, on the rate of extraction was investigated to explore their applicability in solvent extraction. Nonionic surfactants were found to enhance the rates of extraction to different extents in different metal systems.

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A simple process to obtain onion oil by direct solvent extraction was proposed. Several solvents commonly utilized in the food industry were tested for their selectivity in the extraction of the oil of onion. Diethyl ether and methylene chloride appeared to be the most suitable solvents for the extraction operation. The direct solvent extraction method produced a yield of onion oil approximately seven times higher than the yield obtained by the steaim distillation method. A process of fermentation of the ground raw onions was used prior to the solvent extraction operation. This produced an improvement in the onion oil yield of 60% over the normal solvent extraction method. In order to determine the quality of the onion oil obtained, refractive index, specific gravity, melting point, and sulfur content were determined. Sulfur content in the onion oil obtained by the method proposed here had one-third (weight basis) of the sulfur content of commercial onion oil. Two organoleptic evaluations were conducted for commercial onion oil and for the onion oil obtained by direct solvent extraction: odor threshold determination and comparative flavor evaluation. The commercial onion oil showed a lower threshold concentration (1.6 ppb) than the onion oil obtained in the laboratory (8.4 ppb). With respect to the comparative flavor tests, the test panels did not detect a statistically significant difference between the flavor of commercial onion oil and the oil obtained by the method proposed here. / Graduation date: 1982

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A novel technique of direct copper precipitation from a loaded chelating extractant using hydrogen in an autoclave (pressure hydrogen stripping) was studied. In its simplest form, the reaction is given by / {CuL(,2)}(,org) + H(,2)(g) (--->) 2{HL}(,org) + Cu(s). / Kelex 100 (Sherex Chemical Co. - commercial solvent extraction reagent), an alkylated derivative of 8-hydroxyquinoline was used as the basis of the present investigation and represents HL in the above equation. / Two types of experiments were carried out: (a) those designed to study the chemical and thermal response of the extractant at high temperature and hydrogen pressures and (b) those which describe the chemistry and kinetics of hydrogen stripping. / The extractant was found to exhibit excellent chemical stability up to 573 K (300(DEGREES)C) and 2.76 MPa (400 psi) hydrogen in the absence of copper. Its chemical stability was somewhat reduced when loaded with copper. In the latter case, some limited hydrogenation of the quinoline nucleus of the extractant and some of the impurities present (furoquinolines) was observed. The chemical stability of the extractant was found to be enhanced when at least 0.52 M of a long-chain alcohol (decanol) was added to the organic solvent (0.4 M Kelex/kerosene). A slow thermal dissociation of the copper chelate was found to take place within the experimental temperature range studied (443 to 488 K). This resulted in copper precipitation and organic regeneration. / Copper in a powder form was found to precipitate rapidly from loaded Kelex 100/decanol/kerosene solvents by reaction with hydrogen at pressures between 0.52 and 4.00 MPa (75 and 580 psi) and temperatures from 443 to 488 K (170 to 215(DEGREES)C). The overall process has heterogeneous characteristics. Nuclei are provided through slow thermal dissociation of the copper chelate. The freshly produced metallic copper, acting autocatalytically accelerates the precipitation kinetics. Reduction of the Cu(II) chelate to Cu(I) complex appears to be the rate controlling step. / In addition to temperature and pressure, the effects of seeding, agitation, copper concentration, ligand concentration and copper chelate age were investigated. Some physical and chemical properties of the copper powder product were also determined.

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