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By R. Salimi

Tricalcium aluminate hexahydrate (TCA) is used as filter-aid for security filtration in the Bayer alumina process. TCA is typically produced on-site by mixing Bayer liquor with slaked lime. Specific properties are required from the TCA to ensure adequate filter throughput, lifetime and importantly effective reduction of solid/colloidal impurities from the solution. The effect of reaction time on morphology and particle size distribution of tricalcium aluminate was studied for a batch experiment at simulated process conditions. It was found that reaction time plays a critical role on the morphology, crystal structure (diameter and crystallinity) and particle size distribution. In the early stages of the reaction, nucleation dominates the crystallization process followed by growth dominated by agglomeration up to a mean particle size of 10 µm. The particle morphology shifted from an irregular shape to more spherical throughout the course of the reaction.

Jan 1, 2014

By P. H. Oliver

"The current theory of how explosives fracture rock offers no explanation for the improvements in fragmentation and the reduction of fly rock and back break which occurs when an adequate inter-row delay time is used. Nor does it explain why fragmentation improves with rectangular drill patterns where the hole spacing may be as much as four times the hole burden.A new theory of rock fragmentation is proposed which builds on the existing theory. It offers rational explanations for the many blast effects which the current theory does not address and the need for adequate timing delays between rows. It improves on the design of inter-row delay timing by defining the length of free-blasted face needed in front of a hole *Retired from Inco Ltd., Sudbury, Ontario when selecting the delay element which will provide an adequate inter-row delay time."

Jan 1, 2003

By Mauro Chiesa

An Overview on the Presentation A.The Markets ?Mining Industry ?Capital Markets ?A Six-Cell Matrix of Strategic Options B.De-Risking The Mining Assets ?The Value-Added ?The Assets: Current and in Development ?The Feasibility Study C.(Questions, and answers) Post-Crunch: Some Maxims ?Three Metal Market Models No Longer Prevail ?New models are uncharted: ?be prepared?(ref: Lord B-Powell). ?Capital markets are pricey & uncertain: be your own financier first ?focus on value and on cash-flow (not oz, lbs, tonnes, LOMs, etc) ?Know your banker/financier(and it should know mining) ?In the past, it was ?know your borrower? ?It?s a buyer?s market that wants the ?right deal?: so cast a big net: ?Data must be current, concise and consistent ?3rdparty validation of feasibility work is now a ?passport? ?The risk matrix, with de-risking, is as important as the ?math?

May 1, 2011

By Sergio Bustos

A significant expansion project is under way at KATCO?s Torkuduk In Situ Leaching (ISL) operation to increase uranium production up to about 4000 tU/year. Higher flows and lower uranium concentration are expected in the rich solutions coming from the well fields. Therefore, extra adsorption and elution columns and modified operating conditions are required to deal with the increased demand for uranium transfer from the ISL solutions to the eluate solution, which goes to the uranium precipitation section. Resin adsorption and elution performance have been interpreted and projected by using Mac Cabe-Thiele equilibrium diagrams. The resin load, the adsorption mass transfer coefficient, the adsorption zone height and the eluate concentration have been estimated for the expected changing operating conditions associated to the future mine plan. This information has allowed to improve the present operation results and to define the main process design criteria for the expansion project.

Aug 1, 2010

By B. C. Legg, G. L. Tiley

"Many of the ore bodies presently being developed are in remote locations and are, or will be, served by electrical power supply systems of limited capacity.The largest single components of the electrical systems of an underground mine are usually the production hoist drives; the power demands of these drives vary continuously throughout each hoisting cycle.Before 1970mine hoists were driven by either wound rotor induction motors or DC motors in conjunction with motor generator sets.Static Power conversion equipment now costs less to purchase and install and is claimed to be more efficient than motor generator sets. On the debit side, however, it can adversely affect the hoist motors, it operates at relatively low power factors, and it produces harmonic currents.This pa per discusses the effects of static equipment on both DC motors and AC power systems, and evaluates the relative consumption of the three classes of drives."

Jan 1, 1993

By Rodrigo Craig Cerello

The Brazilian economy has always presented a strong correlation with the mineral activity. Since colonization days, due to the territorial expansion caused by the explorers search for gold, mining in Brazil became a basic sector of national economy. Currently, the Brazilian mineral sector¹ estimates a 550% production increment (Figure 1A) in the last 10 years, reaching the US$ 50 billion value, reflecting the increased global demand for raw materials from mineral origin. According to the Brazilian Constitution², mineral resources belong to the Federal State and, consequently, their exploitation must be authorized, under penalty of engendering federal crime. Furthermore, activities of this nature are prone to cause environmental degradation such as, but not limited to, deforestation, pollution, soil deterioration and water contamination. The GPEMA represents the forensics group of the Brazilian Federal Police responsible for the technical analysis of traces related to crimes against the environment and consequently, illegal mining cases.

Aug 1, 2013

By Y. Vermeulen, J. Simoes, P. Guillo, A. Di Donate

New design techniques have been developed to optimize continuous casting (CC) refractory components. The overall objective is to increase CC productivity as well as steel quality by using optimized refractory from tundish-to-mold. These techniques allow the prediction of steel and refractory chemical interactions and, thus, steel chemistry evolution as well as build up and corrosion occurrence. Specific fluido-dynamic models (CFD) have also been developed to better take into account the physical parameters at the steel/refractory interface and to optimize steel flow control. The CFD model can be coupled with refractory chemical interactions to simulate steel chemical evolution. These two different approaches result in shape and material modifications. They are completed by dedicated thermal stress analysis in order to improve thermal shock resistance. The mechanical FEA evaluations take into account specific mechanical behavior of refractory components as well as high temperature evolution of their properties.

Jan 1, 2004

By Xiao Huang, Jean-Francois Thibault, Ali Merati, Prakash C. Patnaik

Single-crystal nickel-based superalloys are the current state-of-the-art technology for the manufacture of turbine blades. This technological improvement of the turbine blade has brought a considerable increase in its cost. Repair and overhaul of service stressed single crystal turbine components is an economic necessity for life cycle cost reduction of engines since the cost associated with replacement is significantly higher than its counterpart polycrystalline component. This paper will first review the recently reported research in developing repair technologies used for DS and SX components. These techniques repair the crack or defect while at the same time ensuring that the mechanical properties do not deteriorate and, more importantly, that the single-crystal microstructure is not jeopardized. It will then be followed by a brief overview of the research conducted and initiated by the authors with regards to the repair of single crystal alloys.

Jan 1, 2004

By C. Bissue, G. M. Castillo

Newmont’s Phoenix mine started production in March of 2006. Due to the extreme hardness of the ore, the mill has struggled to meet throughput projections. Grinding studies showed that optimizing the existing circuit would not achieve budgeted throughput. These studies also showed that the pebble crusher was being underutilized due to the inability of the SAG mill to break the rock. The concept was developed to supplement the feed to the existing pebble crusher with a secondary crusher. Models of this process looked favorable so a portable crusher was installed to test the process. The temporary crusher was successful at increasing the throughput by 7% and based on the operating data, plans are currently being developed to install a permanent secondary crushing system in front of the SAG mill. This paper will review the results from the test crusher and the flow sheet for the permanent secondary crusher.

Jan 1, 2012

By Yongqiang Liu

Background For refractory gold ores with high carbonate contents ! Acid pressure oxidation ! High acid consumption (if low sulfur content) ! Low oxidation efficiency due to CO2 in autoclave ! Problems with slimy precipitates (gypsum, etc.) ! Alkaline pressure oxidation ! Difficulty in fixing arsenic ! Low gold dissolution due to iron hydroxides/oxides coating ! High reagent costs Summary ! Carbonate and sulfide minerals had similar floatability across the pH range tested (5 - 12) using sodium oleate as a collector; ! Thioglycollic acid or citric acid depressed the flotation of pyrite but could not depress chalcopyrite when used alone; ! Combination of thioglycollic acid and citric acid had a much stronger depressive effect, and the mixture depressed chalcopyrite as well as pyrite between pH 8 and 11 without affecting the flotation of calcite and dolomite; ! Calcite could be separated from chalcopyrite and pyrite; dolomite could be separated from pyrite but not from chalcopyrite under the tested conditions.

Apr 1, 2005

By Niels Verbaan, Ron Molnar, David Dreisinger

"An acidic chloride leach solution was generated from the treatment of an ore containing the following value elements: silver, gold, indium, gallium, copper, zinc and lead. Iron was also co-extracted into solution as a ferric chloride species. Iron extraction was a significant component of the overall acid consumption of the leaching process. The recovery of iron by solvent extraction and water stripping was investigated. Tri-butyl-phosphate (TBP) was very effective at recovering iron from the leachate. The water strip solution could be decomposed to produce ferric oxide (hematite) and hydrochloric acid for recycle via hydrothermal hydrolysis or pyrohydrolysis.INTRODUCTION The Malku Khota deposit is situated in the eastern part of the Bolivian Altiplano at elevations between approximately 3,800 and 4,580 meters above sea level (Figure 1). The project is located 98 km east-southeast of Oruro, and 85 km south of Cochabamba in a relatively remote area."

Jan 1, 2016

By William DeWit

When rivers are contaminated from industrial operations, as often occurs near repositories of spent mine tailings, decision-support tools can be critically important in evaluating the effectiveness of various engineering impact-management measures. Even where data describing river flows and quality are sparse, simple mixing-zone models can be constructed that can contribute greatly to understanding how impact-management measures can differentially affect existing river-chemistry regimes. There can be circumstances where accumulated surface waters near contaminated land can bear contaminant loadings that could be acceptable to river regimes if there were methods available to evaluate optional discharge rates and to predict post-mixing consequences on river chemistry. Nomographs can be constructed to evaluate discharge regimes that appear capable of releasing contaminated accumulated pond water without compromising water quality in a nearby river. River-mixing zone models also contribute to predicting rates of acceptable discharge and release to the receiving environment.

May 1, 2011

By Paul Clayton

Case Study ? Site: BMA Saragi Coal Mine Queensland Australia ? Model: Marion 8050 ? YOM: Mid 1970s ? Boom: 97M ? Bucket: Original capacity of 100 Tonnes upgraded to 125 tonnes at time of filtration upgrade. ? Apps: Swing, Hoist & Drag Gearboxes ? Oil: Oil Castrol Alpha TT1200 Viscosity of 1208 cSt @ 40° C (104° F) 720ltr Oil Volume Trial and Installation Justifications ? To reduce gearbox overhauls. Typical schedule being 5 years. ? Bucket upgrade from 100 tonnes to 125 tonnes. Increased gearbox demand and stress. ? Increase of overhauls out to 10 years + ? Saving per Dragline estimated to be US$8-10M in downtime and maintenance if successful. ? In compliance with BHPBilliton Global Maintenance FLAC program ? Fuels, Lubricants, Air and Coolants ? Cost Justification ? Downtime: 4 days ? Lost production: $420,000 ? Cost of parts: $162,000 ? Labour and misc: $41,000 Gearbox failure cost $623,000

May 1, 2008

By D. Lessard, S. Nantel

"Surface crown pillars are important Canadian,mining structures. Mines operating in the Canadian Shield usually have several, forming a first line of protection from surface elements.Detailed technical information from twenty-four Canadian hard rock mines show that the deposits dip steeply and are generally either single or multiple veins. Considerable overburden usually cap the deposits. The rock mass is often altered and intersected by important discontinuities.The designs for these types of pillars lack basic data and are based on experience rather than a scientific approach. Regardless of the competence of the rock mass, the surface crown-pillar thickness to width ratios (an unscientific design tool used by the industry) are usually less than five. Rock bolting is, in almost every case, used as a support measure. However, there are many openings neither backfilled nor monitored.The characteristics of openings with surface crown pillars are also examined."

Jan 1, 1988

By D. G. Ingram

This paper reviews the operating and maintenance practices at Bethlehem Copper from the commencement of operations in November 1962 to the present. Cost data and wear life of major components are also discussed.

Jan 1, 1979

Caterpillar Inc The world's largest manufacturer of construction and mining equipment, diesel and natural gas engines and industrial gas turbines. Technology leader in logistics, construction, transportation, mining, forestry, energy and electric power generation.

Aug 1, 2013

NANA Accepts Mining ­ 1974 - Leadership presented mining option to people ­ Community meetings; recognized need for cash economy ­ 1979 - Poll shows consensus in favor of mine development ­ 1980 - Shareholders approve mining; Congress approved land selections

May 1, 2002

By M. Samuels

"Block and panel cave mining methods are being increasingly proposed as they allow massive, deeply situated ore-bodies to be mined economically at a time when discovery rates of significant near surface deposits are declining. Cave-to-Mill, a mine-to-mill approach for block cave mines, defines ore block models with respect to both mine and mill performance. A cave-to-mill study for the New Afton block caving operation focused on identifying value opportunities related to fragmentation and sorting for a future lift as development progresses deeper. The lack of selectivity and potential for dilution associated with the block cave mining method results in many caving operations having to mine and either dispose of or process material that is below cut-off grade at certain stages of production. As an outcome of the study, the variation in cave fragmentation size and the sensitivity of mill throughput to feed size was examined. To evaluate the amenability of bulk and particle sorting, Prompt Gamma Neutron Activation Analysis and X-Ray Fluorescence sensors were tested. A conceptual bulk and particle sorting flowsheet is presented. Grade data from regular underground sampling was used to predict the performance of a bulk sorter. A heterogeneity analysis of material reporting to drawpoints helped to identify areas of the extraction level that experience high variations in grade and thereby stand to benefit from dedicated ore and waste material handling systems should underground bulk sorting be implemented.INTRODUCTION Block and panel caving are low-cost underground mass mining methods that are suitable for excavating weak, massive and steeply-dipping orebodies. Accordingly, cave mining methods have predominantly been used to mine copper porphyry and diamond bearing deposits. Due to the increasing depletion of near-surface orebodies, it is expected that block and panel caving methods will be increasingly used in the copper-gold industry. Their implementation holds significant potential to extend the life of existing open-pit operations by providing an economic means to access ore located at depths that are beyond the practical limits of open-pit mining. Examples of cave mines proposed for British Columbia include the Kwanika Mine, Red Chris underground, Kemess Underground project, and the Iron Cap and Mitchell cave mines of the Kerr-Sulphurets and Mitchell (KSM) project (Moose Mountain Technical Services, 2017; Imperial Metals, 2017; Golder Associates, 2017; Tetra Tech, 2016)."

Jan 1, 2018

"In response to mine head grades declining and orebodies becoming more complex, Glencore Technology has developed an alternative method for recovering economic minerals once leached into solution, rather than relying on conventional flowsheet options. The method involves the precipitation and separation of base metals from solution with limestone or lime. The final grade of these precipitate is not usually high enough to attract favourable terms of sale due to dilution from gypsum and sulphate salts. A set of operating conditions have been developed to allow the separation of the base metal precipitate from gypsum by exploiting the difference in particle size. A high-grade oxide product can be easily separated from the gypsum stream at very low cost. This process was originally developed by Glencore for zinc and copper systems. This paper reports on the successful application to nickel and cobalt, and this process has significant advantages over the incumbent precipitation process utilising magnesia.INTRODUCTION During evaluation of transitional and oxide zinc ore deposits during the 1990’s, Noranda Inc. (now Glencore) developed a sulphate based ore leach process to extract zinc into solution. For flowsheet development, conventional schemes dictated that once the zinc was dissolved in an acidified solution it was recovered by means of purification or solvent extraction followed by electrowinning and casting to produce zinc ingots. The deposits Noranda evaluated were high grade but had a relatively short mine life (10 years) and economic analysis showed that the projects couldn’t sustain the investment of a full zinc refinery. Compounding this problem was the lack of power supply infrastructure and the high power cost in the region. Noranda then evaluated alternative means of recovering zinc from solution. Laboratory testwork showed that a high-grade zinc precipitate (+50 wt% Zn) could be produced as an oxide, carbonate or sulphide by contacting acidified zinc sulphate solution with a number of reagents including soda ash, sodium hydroxide, and sodium hydrogen sulphide. Economic evaluation showed that the cost of the reagents are prohibitive, especially when the final product is still a metal intermediate (ZnO, ZnCO3 or ZnS). Noranda then continued to focus on fine zinc oxide precipitation for supply into the automotive tyre industry as this product would attract favourable terms of sale as a premium on Special High Grade (SHG) zinc."

Jan 1, 2017

By Arthur Notman

For the period January 1st, 1942, to January 1st, 1946, the American Bureau of Metal Statistics records the gold production of the world as 118,788,000 fine ounces. If we include 1946 at the same rate as 1945 (26,- 590,000), we arrive at a total of 145,378,000 fine ounces in the past five years . Included in these figures are estimates of Russian output at 4,000,000 ounces per annum for the five years, and 1,300,000 ounces per annum for Korea and Japan. The remaining 120,000,000 ounces represent the aggregate production from official reports of the other gold producing areas of the world, with the exception of the 1946 figures, as noted above. At $35.00 per fine ounce, this represents $5,188,230,000. According to the reports of the Federal Reserve System of the United States, on December 31st, 1941, the monetary gold reserves of the United States were $22,736,- 600,000 (at $35.00 per fine ounce) , while on October 31st, 1946 (latest available) , they had fallen to $20,402,000,000, a decline of $2,334,600,000. Adding this decline to the value of the new production for the five years, we have a total of $7,522,830,000, which has been absorbed by the rest of the world since Pearl Harbour, a rate of absorption of over $1,500,000,000 per annum. This has taken place at a rime when the advocates of purely managed currencies had convinced many people that gold performed no really essential function in the world's economy, and that we could get along perfectly well without it. It was pointed out that gold could not be eaten, it could not clothe our nakedness, it could not shelter us from storms, and, therefore, it was a non-essential, even though it could be used to settle international balances of trade. Apparently, the world as a whole still regards it as preferable to the paper promises of governments, however sound, relatively, they may appear. Actually, we have no way of measuring the true strength of this feeling, because the principal governments of the world have made it legally impossible for their citizens to own gold, except in the form of ornaments.

Jan 1, 1947