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roasting operations. Sulfur oxide releases from the autoclave vents are notsignificant because iron dissolved in theacidic autoclave slurry catalyzes thecomplete-oxidation of sulfide to sulfateinstead of more volatile sulfur dioxide.
In other parts of the process atMcLaughlin, atmospheric emissions arevery similar to more conventional goldrecovery operations. However, the regulatory climate in the environmentallysensitive area of California surroundingthe mine made it necessary to forecasttypes and quantities of substances thatwould be released from all anticipatedair emission sources, and to verify thoseforecasts by performing source tests onthe commercial operating facility. CH2MHILL successfully completed the sourcetesting program following plant startupand stabilization in 1985. This is believed to be the first time a commercial
gold recovery facility has been so exthe atmosphere.
The McLaughlin Mine gold recoveryprocess also has several other favorable attributes, contributed in part by autoclaving. One important feature is thatby oxidizing the sulfide fraction of theore, the potential for acid formation inthe tailings is removed. This eliminatesthe need for extraneous measures forcontrol such as enhanced containmentstructures.
Another benefit provided by autoclaving is a reduction in reagent consumption in the carbon-in-pulp (CIP)circuit. This is achieved by bypassingreagent-consuming constituents that aredissolved during autoclaving around theCIP circuit (via the decant neutralization/precipitation circuit in Figure 1). Anadditional benefit is that, because reagent consumption is reduced, process
tailings contain lower concentrations ofresidual reagents. These levels are fursuming components are recombinedwith CIP tailings for placement in thetailings impoundment.
The process at the McLaughlin Minehas earned acceptance for preservingenvironmental quality in an environmentally sensitive region of Californiawhile proving to be efficient and economic as well.
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UMC Book Review Program
Metallurgical Calculations - Part IVA.E. Morris, James StephensonUniversity of Missouri-Rolla Rolla Research Center, U.S. Bureau of Mines
The exclusive book reviews appearing in Journal of Metals each month are anexceptional member service. A cooperative effort with the University Materials Council (UMC) enables the Journal to maintain the most comprehensive review programanywhere in the field of materials engineering. The UMC represents the departmentheads of the metallurgy and materials science schools in the United States.
The UMC book review program operates through designated contact persons atparticipating universities, who disseminate review books acquired by the Journal. Ifyou are interested in being part of our mailing list, please contact Shirley Miller at(412) 776-9070.
than the main oxide lower the temperature of its transition to intrinsic conduction, reduce the breadth of theforbidden zone and raise the reactivityof oxides. The study of the admixtureinfluence on properties of metallic oxides has clearly revealed a link betweenelectrophysical properties and reactivity. The established regularity of admixture influence on electrophysicalproperties and the reactivity of metallicoxides makes it possible, in principle,to control the process of interaction between metallic oxides and other agents.
Researchers have revealed the common electronic nature of the conductivity of metallic oxides and their reactivity.Their work indicates that a rise in theconcentration of free electrons in thesystem, necessary to intensify physicaland chemical processes, can beachieved by introducing donor additivesand other physical methods of influencebesides traditional heating. This discovery can be applied to intensify physicaland chemical processes in metallurgy,chemical technology, the production ofcomposites, semiconductor materialsand other economic sectors.
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JOURNAL OF METALS. January 1987
MAINFRAME SYSTEM:SHIMPO·GOTO
SHIMPO-GOTO Version III is writtenin FORTRAN 77 and is used for calculating molar amounts of variousphases at equilibrium in large chemicalsystems at a given temperature andpressure. The package allows a moreflexible input than Versions I or II. Inaddition, heat balance calculations maybe done by providing input of molal heatcontents, temperatures of transformation for components below their reaction temperature, and heat contents ofcharge components. All data must becarefully prepared before execution, andthere is no way to change data after
entry because of batch processing. Mostconference attendees found the program to be the most difficult to evaluate,even with the assistance of workshoppersonnel. Once correct input of datawas achieved, the results were quicklyand accurately attained.
The has been the fourth installment ofan eight-part series which is examiningsome of the programs featured at theComputer Software for MetallurgicalCalculations Conference, which tookplace late in 1985 at the University ofMissouri-Rolla.
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