372595899

JPRS-UMS-92-003 16 March 1992

EXTRACTIVE METALLURGY, MINING

43

magnets and the process indicators of a magnetic sepa-ration process requires knowing the naturę of the change in the key parameters of the magnetic field in the separatoris live zonę. Analytic methods of describing the said parameters by proceeding from the condition of the equipotentiality of the poles’ surface is available for use with electromagnctic magnetic-gravitation separators. This condition of equipotentiality is violated in magnetic systems consisting of fiat permanent magnets because the force lines in such cases are not at a 90° angle to the pole surface. A new method of calculating the distribution of magnetic potential in a system of permanent magnets has been developed to allow for the force lines that occur when fiat permanent magnets are used. The new method is based on the familiar method of mirror representations and is modified to allow for two additional assumptions. These assumptions are as fol-lows: 1) the opposing magnetic Circuit planes do not distort the permanent magnets’ field, and 2) the magnetic Circuit has a resistance of zero. An analytical description of a system of two magnets located in a homogeneous medium with a magnetic permeability of Po is then derived by using the concept of complex magnetic potential. To estimate the error of their new method, the researchers tested it on physical models of magnetic systems using KSP-37 permanent magnets with an induction of 0.1 T on the central part of their surface. The new method proved to be highly reliable in describing the magnetic field in the interpolar gap of a system consisting of fiat permanent magnets. The new method was deemed effective for quickly determining the optimal magnet dimensions and distance and angle of the gap between the two magnetis in both wedge-shaped and piane open systems. The new method has been used to develop a number of fiat permanent mag-net-based magnetic-gravitation separators that are being used successfully to enrich gold-containing microsec-tions. Figures 5; referenccs 2 (Russian).

The Effect of pH on the State of Fatty Acid Collectors of Heavy Metal Ions in Solutions

927D0090A Ordzhonikidze IZYESTIYA WSSHIKH UCHEBNYKH ZA YEDENIY: TSYETNA YA METALLURGIYA in Russian No 2, Apr 91 (manuscript received 28 Aug 90) pp 2-5

[Article by L.D. Skrylev, V.F. Sazonova, T.L. Skryleva, and Ye.A. Yakhova, Physical and Colloidal Chemistry Department, Odessa State University]

UDC 622.765:541.183

[Abstract] The authors of the study reported herein performed a mathematical analysis demonstrating that a quantitative link between the pH of aqueous Solutions of alkaline metal soaps and their critical concen-tration of micelle formation may be easily established by considering the process of micelle formation from the principles of phase equilibrium and by assuming that the “solubility product” concept is applicable to micelles of soaps. They presented both calculated and experimental data confirming that there is a straight-line dependence (with a slope of Vi to the abscissa) existing between the log of the critical concentration of micelle formation of alkaline metal soaps and the pH of their Solutions within the rangę of pH values ensuring adequate stability of the soap micelles and meeting the requirement that [H*] >> K*. (KJ being the total concentration of RCOO* ions and RCOOH molecules in a saturated soap solution. This finding led them to further hypothesize that when [H*] » K* still holds true but the micelle solution also contains fatty acids, the dependence between pH and the log of the critical concentration of micelle formation will be described by an equation represented by a straight linę with a slope of 1 to the abscissa. This did not tum out to be the case, however. Instead, the critical concentration of micelle formation remained virtually unchanged as the pH changed. This led the authors to hypothesize that in media with a rather high concentration of hydrogen ions, the dissociation of fatty acids is essentially completely suppressed, and the critical concentration of micelle formation of fatty acids is in fact not dependent on the pH of the medium. The studies performed thus led the researchers to conclude that the colloid-chemical State of fatty acid ion collectors of heavy metals in a solution (which by and large determines their technological characteristics) depends on the pH of the solution. They further concluded that when the solution’s pH drops below a certain limit (as determined by the naturę of the collector) there is a marked decrease in the collectoris critical concentration of micelle formation that in tum has an adverse impact on its effectiveness. Figures 2; references 10 (Russian).