Annual Meeting Preliminary Program - Full Brochure (PDF) - SME

amount of the organic leaving the system through the aqueous raffinate solution.
Some of the methods used have included operational adjustments,
Jameson Cell, coalescing packs and picket fencing. Each of these solutions
has had some effect on the amount of organic entrainments lost through the
raffinate. Implementation of the methods above has led to significantly
reduce organic entrainment at two Phelps Dodge, SXEW plants in New
Mexico. Similar methods were adopted at other Phelps Dodge sites with
continued success. This paper provides insight as to the methods tested and
results recorded for the two New Mexico sites.
2:45 PM
The Effect of Particle Size and Other Process Variables in the Stripping
of Gold Cyanide from Activated Carbons
F. Elnathan, S. Zheng, C. Lin and J. Miller; Metallurgical Engineering
Department, College of Mines and Earth Sciences University of Utah, Salt
Lake City, UT
Activated carbon is being used extensively for the recovery of gold from
cyanidation plants. However, gold losses on fine activated carbon particles
and the attendant high carbon inventories are quite significant. The effect of
particle size and other process variables on the stripping of gold cyanide from
activated carbon has been studied and will be discussed with respect to chemistry
and procedures for elution.
3:05 PM
Hydrometallurgical Design Considerations at the Safford Leach Project
L. Todd; Freeport McMoRan Americas, Safford, AZ
The Safford Leach Project located in Graham County, Arizona began construction
in 2006 and will begin production in early 2008 at an annual design
production rate of 109,000 tonnes of cathode copper. The project includes
open pit mining, three-stage crushing, agglomeration with sulfuric acid,
conveyor stacking, heap leaching, solution extraction and electrowinning to
produce cathode copper from low-grade oxide ores. The project employs a
number of design features to control project capital and operating costs and
incorporates experience from existing properties. Design considerations of
the hydrometallurgical recovery circuit are discussed in this paper.
3:25 PM
Improvement of Silver Leaching from High Silver Grade Ores Using
the Celp
G. Deschenes; CANMET, Ottawa, ON, Canada
The leaching of silver from high purity silver, high purity silver minerals
(acanthite, stephanite and pyrargyrite) and a mixture of silver minerals was
determined under various conditions and compared to a new leaching process
called “CANMET Enhanced Leaching Process (CELP)”. In the absence of
sulphide minerals, increased dissolved oxygen of the slurry produced the
fastest silver leaching kinetics. For a slurry containing acanthite, a 23% improvement
in silver extraction (from 76% to 99%) was obtained with the
CELP whereas silver extraction increased from 75% to 90% for the slurry
with pyrargyrite. No improvement was obtained for the slurry with stephanite
(99% extraction in 72 hours). However, the silver leaching rate was much
faster with the CELP. The slurries containing the mixtures of minerals
showed improvements of 21% Ag (from 75% to 96%) and 37% Ag (from
56% to 93%) with the CELP. Leaching of a high grade gold/silver ore with
the CELP resulted in higher silver and gold extractions while using a lower
cyanide concentration.
3:45 PM
Electrochemical Study of Gold Cementation onto Copper in Thiosulfate
Solutions
J. Lee 1 and B. Hiskey 2 ; 1 Newmont Metallurgical Services, Newmont
Mining, Englewood, CO and 2 Materials Science and Engineering, University
of Arizona, Tucson, AZ
The electrochemistry of gold cementation in thiosulfate solution with rotating
disk electrode and electrochemical quartz crystal nanobalance has been
investigated. Sodium thiosulfate of 0.25M solution is used for standard condition
at pH 9.5 and initial gold and copper concentrations are changed.
Mixed potential was recorded under various conditions to investigate passivation
phenomena. The characteristics of the potential curves vary according to
the parameters showing different passivation patterns. Evans’ diagrams were
plotted by superimposing polarization diagrams of the gold reduction and
copper oxidation. Corrosion currents increased with increasing gold concentration,
disk rotating speed, and thiosulfate concentration as expected by
kinetic study.
32
Mineral Valuation:
Recent Case Histories and Analysis of Methods
2:00 PM • Monday, February 25
Chairs: E. Moritz, Gustavson Associates, Boulder, CO
J. Gustavson, Gustavson Associates, Boulder, CO
2:05 PM
When Partial Takings Take More Than You Think
R. Frahme; Appraisal, Gustavson Associates, Boulder, CO
Appraisers are often asked to develop an opinion of the value of a partial taking.
It is incumbent upon the appraiser, in the review of the condemnation
documents, to form an independent opinion of the larger parcel(s), the part(s)
to be taken and the remainder(s). Sometimes, the project causes the remainder(s)
to have no economic value. In such cases, the purported “partial taking”
may be tantamount to a total taking and must be appraised as such. This
paper relates some of an appraiser’s experiences in such determinations.
2:25 PM
Use of Comparables Sales in Appraising Coalbed Methane Properties
E. Moritz; Gustavson Associates, Boulder, CO
There has been a surge in interest in the acquisition and development of
coalbed methane properties. Depending on the location, coalbed methane
projects require economies of scale and other considerations in order to be
attractive. The appraisal of such acreage can be complex especially if the
acreage is undeveloped and some distance from production. This paper
describes the use of comparable sales as one method to approach a value in
the appraisal of coalbed methane properties. Case histories from certain areas
of the Rocky Mountains are presented.
2:45 PM
Property in Transition — Appraisal of Mining and Upscale Residential
Use, Saguaro National Park, AZ
J. Gustavson; Gustavson Associates, Boulder, CO
The claim named Comet 1 is located on Yuma Mine Road near Tucson. The
Saguaro National Park nearly surrounds the parcel with unfriendly, private
neighbors to the north. A Validation Examination was provided. Patenting
was recommended by BLM for gold-lead mining. Interior found no legal reason
why the mining patent would not be issued. Appraisal includes other
value since residential land value will surpass that of mining. Maximally productive
use then changes to residential. FMV is estimated as the sum of transitional
mining and long-term residential use. The former was estimated on a
lease basis similar to appraisal in temporary takings, where Fair Market
Rental Value may be estimated. Claim changed to residential use after 5 years
of mining. Adjustment was made for availability of access through mining
use. Cost of access by necessity and construction of road are included in the
mining use. Reclamation for residential purpose is included. Value was adjusted
based on appreciation in Tucson residential market. The transitional
value and the long-term value were added, yielding the FMV. Both private
owner of claim and NPS agreed to the FMV for purchase by the NPS.
Mining & Exploration: Surface Mining: Big Pits
2:00 PM • Monday, February 25
Chair: T. Swendseid, Phelps Dodge Sierrita Inc, Green Valley, AZ
2:05 PM
Suncor’s Big Rocks, A review of mine productivity initiatives
L. Hale; Mining, Suncor Energy, Fort McMurray, AB, Canada
Suncor Energy operates a large open pit mine as part of an integrated oil production
facility in Northern Alberta. The 2008 mine plan calls for over 450
million tonnes. Mining Oilsand presents a unique set of challenges and a
combination of specialized equipment and mining techniques make this an
interesting application of technology. This paper will introduce Suncor
Energy and review our mine hauler tire life program and a number of productivity
initiatives that were successful in allowing our mine to meet our aggressive
growth and production plans.