Linear Polarization Measurements at High Temperatures in Hypersaline Geothermal Brines

Linear Polarization Measurements at High Temperatures in Hypersaline Geothermal Brines

Author:

Publisher:

Published: 1978

Total Pages:

ISBN-13:

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The Bureau of Mines conducted a series of in situ linear polarization measurements in high-temperature, high-pressure hypersaline geothermal brines at the Bureau of Mines Geothermal Test Facility in the Imperial Valley of California. The measurements represented an evaluation of the linear polarization technique for obtaining instantaneous corrosion rates of materials of construction in flowing hypersaline hydrothermal fluids that rapidly form scales on exposed surfaces. A special method was devised for use with the linear polarization technique that resulted in obtaining corrosion rates for 1020 carbon steel, 316 and 430 stainless steel, titanium, various nickel-based alloys, and aluminum 6061 under strong scale-forming conditions. The measurements also provided information on scale-deposition rates in various geothermal environments. Exploratory in situ potentiostatic polarization measurements were made in the flowing brines to qualitatively determine scale-deposition effects on the electrochemical measurements.


Cobalt and Nickel Removal from Zinc Sulfate Electrolyte by Solvent Extraction and Precipitation Techniques

Cobalt and Nickel Removal from Zinc Sulfate Electrolyte by Solvent Extraction and Precipitation Techniques

Author: Richard G. Sandberg

Publisher:

Published: 1978

Total Pages: 500

ISBN-13:

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Sphalerite concentrates prepared during processing of Missouri lead ores contain small percentages of cobalt and nickel which adversely affect zinc electrolysis. The Bureau of Mines has evaluated solvent extraction and precipitation techniques to remove and recover cobalt and nickel from zinc sulfate solution prior to zinc electrolysis. Prepared zinc sulfate solutions containing about 190 gpl of zinc and 50 ppm of both cobalt and nickel were treated using various combinations of complexing reagents, solvent, pH, concentration, time, and temperature. The following complex reagents gave the best results a-nitroso-ßnaphthol, ß-nitrosos-a-napthol, 1,2 cyclohexane dione dioxime (nioxime), di-2-pyridyl ketone oxime, and dimethglyoxime. These reagents in suitable solvents lowered the cobalt and nickel levels to