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By Warren N. Warhol

The mutual growth of the rare earth industry and the Mountain Pass Operations was no coincidence. It was the commercial availability of rare earths on a scale first made possible by the capacity of the Mountain Pass Operations that spurred research and development efforts toward new applications for rare earths. The first important demand on Mountain Pass was europium oxide for the activation of red phosphor for color television tubes in 1964. Since that time, other rare earths have become even more important, and Molycorp is continuing to supply an ever widening variety of rare earth concentrates and compounds. We enjoy saying that rare earths are not really rare, and that they are not earths, either. Of course, we are talking about the 15 metallic elements with atomic numbers 57-71, called the lanthanides, which occur in nature always together in very similar proportions. Their scarcity can be gauged by the fact that there is more cerium in the earth's crust than there is tin, and more europium than cadmium. The word "earths" comes from the early chemical term for oxide. The rare earths were discovered as oxides, and the term has persisted.

Jan 1, 1980

By D. C. Hatch

At the MacIntyre Development of the Titanium Division of National Lead Company a magnetite-ilmenite ore together with gabbro-anorthosite waste is mined from an open pit by shovels and trucks. The ore from the pits is trucked to ore stockpiles for blending ahead of the crusher and to free the mine from crusher delivery schedules. The ore stockpiles are blended to yield a 16.5 to 17.0 % TiO, crusher feed. This requires mining on an assay cut-off rather than a visual grade cut-off. Highly mineralized ore runs from 20 plus % TiO2 and 30 plus % Fe to 15 % TiO2 and 40 plus % Fe as the ratio of ilmenite to magnetite changes. There are three major ore types in the present pit with magnetite ratios varying from about one to one up to three times as much magnetite as ilmenite. Ilmenite and magnetite together liberate from gangue down to about 10 mesh and this is the basis of the magnetic cobbing. Below 10 mesh the ilmenite and magnetite start to separate and ore cobbing pulleys will not hold the ilmenite.

Jan 1, 1968

By Gregg J. Hodges

The Stillwater pt-pd mine and flotation mill are located about 130 km (80 miles) southwest of Billings in Stillwater county, M6ntana~ The pt-pd ore zone stretches about 43 km (27 miles), but varies in thickness from 0 to 6 meters (0 to 20 feet, but generally 3-6 feet) and dips 55-90,degrees from horizontal. The ore is hosted in basic, layered igneous rocks containing about 1% sulfide minerals which include chalcopyrite, pentlandite, pyrrhotite, and minor pyrite. The pt-Pd minerals are intimately associated with these sulfide minerals and are found as precious metal sulfides, tellurides, bismuthnides, and arsenides as well as native Pt metal. Approximately 90 different precious metal minerals have been found, but about 80% of the pd is in solid solution in the pentlandite. The ore assays about 0.1% Cu, 0.1% Ni, 6.2 g Pt/tonne (0.18 Troy ounce Pt/short ton (opt)), 21.3 g Pd/tonne (0.62 opt Pd), 0.21 g Au/tonne (0.006 opt Au), and 0.21 g Rh/tonne (0.006 opt Rh). The ratio of pd to Pt in the Stillwater ore and concentrates is about 3.5.

Jan 1, 1988

By J. E. Osmanski

This semantically ambiguous title purports to describe an examination of the question of automation and its effect on the industrial worker. More explicit titles might be "Painless Automation" or "Mechanization without a Sting" or, if I may steal a few phrases from the title of a recent interview Pith John L. Lewis, "More Machines, Fewer Men -- Is the Union Happy About It?" Automation has become the biggest ?scare word? for many industrial workers and their unions since "wage stabilization.? "To many a union orator," reports TIME of January 4, "automation is the sinister business of eliminating jobs." TIME might better have phrased this description by saying that many unions regard automation as the attempt to eliminate not jobs, but workers, The recent steel dispute was hung up for so long primarily because of the problems evolved of increased job efficiency through automation and job changes. Everywhere today there is heard the cry of our need for maintaining full employment within the context of an expanding economy echoing against the sheer reality of automation's displacement of thousands of workers through a rapid acceleration of productivity.

Jan 1, 1960

By Jon G. Baird

The suggestion of the use of measurements of trace amounts of mercury as a guide to the location of sulphide ore deposits was first made by the Russian, A. A. Saukov (1), in 1.946. Since Saukov's original work, many others have studied the abundance of mercury in nature, the association of mercury with sulphide ores and methods by which very minute quantities of mercury can be measured in air, soil, rocks, water and plants. The most abundant of the mercury bearing minerals is cinnabar (HgS). Native mercury is also found and sulpha-salts like tetrahedrite are known to have important mercury contents. Other sulphides of base metal deposits contain mercury in amounts ranging from parts per million to as much as one or two percent. (2) The mercury content of sulphide-free rocks is usually less than a few hundred parts per billion (1 ppb - 10-9), Soils usually contain less than 100 ppb and water less than 1 ppb of mercury. Normal atmospheric air contains about 1 nanogram (10-9 grams) of Hg per cubic metre although higher concentrations can be observed near mercury occurrences, sulphide deposits and volcanic exhalations.

Jan 1, 1973

By E. F. Young

An integrated steel company is an industrial complex ranging from raw materials mining, through pyrometallurgical smelting and refining, and hot shaping, to product finishing and coating. Within this complex is a great variety of operations which use vast quantities of water, and a variety of water uses which can result in pollution of many different types. The industry has recognized most of its problems for some time, and has spent a great deal of money and effort in reducing and eliminating pollution. A recent survey by AISI showed that the industry has spent, within the last 15 years, two hundred forty millions of dollars on water pollution control, and has authorized spending eighty-seven millions more on this type of non¬productive facilities. While much still remains to be done, I think the record to date is one we can be proud of. In this presentation, we will attempt to outline a number of the water pollution problems encountered in an integrated steel company and to show what types of corrective action have been and are being taken, using Jones & Laughlin Steel Corporation as an example.

Jan 1, 1968

By R. W. Bartlett

Computer deterministic models for predicting the time dependent extraction of copper by leaching fragmented rock (both in situ and heaped or piled) have been presented in the last two years by Bartlett1, Braun, Lewis and Wadsworth2 and Roman and Co-Workers.3 All of these models involve aqueous diffusion within the pores of the rocks from which the metal is being extracted. The rate of chemical dissolution of the ore mineral within the rock will also affect the kinetics in the case of sulfide copper ores and some of the more refractory oxide copper ores. Simulation is also needed for fine grain disseminated gold ores and low grade uranium ores that may be heap leached. The development of such leaching models has two major purposes: First, extraction estimates must be made for tong time periods particularly for situations where laboratory and field tests either cannot be made or where there is insufficient time for field testing. Second, the results of simulated leaching should indicate the relative importance of the extraction controlling parameters and, thereby, provide a better understanding of the complex leaching phenomena on heaped material being leached, and guide further experimental work.

Jan 1, 1974

By Diane M. Jordan Tom M. Malloy

As part of the Mine Waste Technology Program (MWTP), a large-scale column test utilizing bacteria and a sulfide ore was conducted at McClelland Laboratories, Inc., in Sparks, Nevada. The MWTP is funded by the U.S. Environmental Protection Agency (EPA) and is jointly administered through an interagency agreement with the U.S. Department of Energy (DOE). The project was intended to illustrate the viability and feasibility of biodegradation technologies to reduce the cyanide to the regulatory level of 0.2 parts per million (ppm) within an acceptable time frame and with low operational costs.

Jan 1, 1999

By James Whitlock, Michael Robert Wilcox

The volume of recently published material in praise of various refractory gold ore treatment methods is impressive. The authors are unfailingly bright, focused and thorough, and as each paper concludes, the reader is tempted to abandon other methods and embrace this truly better way. But there are many "better ways," many different ores, many different environmental requirements and many differ­ent economic circumstances. As we approach each set of cir­cumstances, it would be useful to have an objective way of comparing various methods in order to identify the most promising approaches. This discussion attempts to provide that.

Jan 1, 1991

By Wolfgang Baum

The selection of roasting technology is a complex task which is primarily dependent on the ore mineralogy. Key roasting parameters are directly linked to mineralogical characteristics of the feed and vary considerably between different ore types even in the same deposit. In addition to sulfide refractoriness, other refractory conditions frequently exist. Together with various mineralogical features of the feed, they may complicate roasting testwork and process design. For most roasting scenarios, the critical economic factors are gold recovery, capital cost and environmental performance. This paper will show how these economic factors are influenced by the mineralogical ore characteristics.

Jan 1, 1992

By F. W. DeVries

The preoccupation with cyanide as an environmental issue has been described as virtually an obsession for state and federal agencies enacting regulations for environmental protection. This seems likely to continue in legislative planning, as well. This is despite the fact that the only significant group of cyanide-related incidents has been the bird-mortality occurrences, predominantly in arid areas, and these have been greatly reduced by a concerted effort by operators. What follows is a brief list of areas for which the industry may need either additional information or plans for defensive strategies over the next two to five years.

Jan 1, 1991

By Ian Larkins

The Ruby Hill Mine agglomerates crushed low-grade ore (nominally -1 .5'') with high-grade filtered tailings (filter cake, nominally 80% -65#). Cement is added as a binding agent. The agglomerated ore is then conveyed and stacked on the heap. In 1998 approximately $480 000 was spent on cement for agglomeration. Cement for mill pH control and agglomeration was the largest single reagent cost at Ruby Hill. In an effort to reduce agglomeration costs a test-work program was initiated to investigate alternative binders and optimum binder additions. This paper summarizes the test­work results to-date.

Jan 1, 1999

By Hans von Michaelis

Very little has been published about Cia de Minas Buena­ventura. Don Alberto Benavides Quintana, now in his seventies, founded the company in 1953. This venerable gentleman is a Doyon of the Peruvian mining industry and more has been known about him than about his company. Buenaventura is a highly profitable gold producer with excellent potential to expand gold production in joint ventures with Newmont, Southern Peru Copper (ASARCO), and BRGM as well by developing their own new gold mines. On September 15, The Wall Street Journal published an article titled "Peru's Big Rebound Sets Off Foreign Investors' Enthusiasm."

Jan 1, 1995

By Brian T. Field

Development of cost effective technology for whole ore roasting of refractory gold ores is an important requirement to increase recovery rates as ore grades become more carbonaceous and sulfidic in nature. It is important that the industry focus on the further development of cost effective, environmentally sound technologies to roast this ore. Traditional technologies have centered around bubbling and circulating fluidized beds with and without oxygen enrichment. Fuller Company has developed a process to flash roast refractory ores in its pilot plant with the R&D results, commercial scale up issues, and indicative economics discussed herein.

Jan 1, 1993

By Marshall A. Koval

The future of mining in the United States is in question. The cumulative effects of federal, state and local environmental legislation threaten its survival as the cost of compliance skyrockets. Legislation has created pol ari zat ion between government and industry followed by court action, further increasing costs and delays on permitting and remediations. Regulations often call for excessive and rigid requirements that result in unrealistic compliance goals costing tens of millions of dollars. The costs often exceed the value of the remedy. A growing concern is that proper scientific methodologies and engineering practices are being sacrificed because of political and public pressures.

Jan 1, 1991

By Chris Cox, David Green

Outokumpu has developed the HG or High Grade flotation cell over the past decade. This machine gives upgrading and selectivity performance superior to conventional mechanical cells while maintaining their simplicity, ease of operation and recovery characteristics. The HG design is available in a tank cell configuration which provides a number of benefits in plant design and operation. This paper will describe the HG Tank Cell and the "Virtual Column" concept. Results are given from the operation of the HG Tank Cells at Lac Minerals - Est Malartic in Quebec, Canada. Further discussion of applications for gold recovery is also provided.

Jan 1, 1993

By G. Petrakis

The selection of suitable species of plants for the rehabilitation of mining disturbed lands is one of the most crucial decisions to be made concerning the success of planting revegetation. Native plant species are best suited for use in the work of reintroducing vegetation in rehabilitated areas. By using such species an increase in the success rate of rehabilitation is attained not only as regards yield due to their better growth ability (they are adapted to local climatic conditions), but also because of a better adjustment to and better visual harmonization with the surrounding unspoiled areas.

Jan 1, 2002

By Qingxia Liu, Chen Tingzhong, Chen Jin, Yang Xiaosheng

It is common problem (Huan Xinsheng, etc.,l992)for most iron ore concentrators in China that the concentration of thickened tailings is lower than the need for economical transportation. To solve the problem, two methods of improving the properties of the existing thickeners and using separate thickening technique have been applied in three iron ore concentrators. However, in the case of the Daye iron concentrator a new technique of cyclone-flocculated sedimentation was developed by present authors and verified by experiments. The new technique employs efficient hydrocydone designed by authors in conjunction with a low cost flocculant named KLP.

Jan 1, 1995

By Maurício Covcevich Bagatini, Maycon Athayde

Water consumption reduction in pellet feed operation is of paramount importance. Compared with traditional ball mills, high-pressure grinding rolls (HPGR) play an important role in Blaine surface area (BSA) generation to improve agglomeration properties, although stability is still a challenge. Grindability improvement of existing operation has a direct impact on the performance of the filtering and pelletizing operation. The results of this study, as a pregrinding operation, can be applied not only in new operations but also in existing ones, helping the operator control process variation in a more effective way while ore hardness increases. 

By J. Cooper, M. W. Staub

Environmental management systems (EMSs) have been in use for more than a decade. US mining companies are only just beginning to adopt EMSs. This lag is primarily due to lack of market forces and lack of evidence that EMSs add value over standard compliance programs. Several recent studies concluded EMSs improve environmental performance and reduce costs. State and federal regulatory agencies are using EMSs as an innovative tool to streamline the regulatory process and achieve continual environmental improvements. The climate is right for the mining industry to adopt an EMS model that improves environmental performance and takes advantage of new regulatory programs.

Jan 1, 2004