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By P. B. Queneau, J. E. Litz, T. P. McNulty

I. INTRODUCTION Modern hydrometallurgy has its roots in such notable successes as heap leaching for recovery of copper, cyanidation of gold ores, the Bayer process, the Oxland process for tungsten, electrorefining of copper, roast/ leach/electrowin process for zinc, and production of yellowcake from lowgrade uranium ores. Metallurgical testing techniques, sampling and analytical procedures, operating and maintenance practices, and improved methods and materials of construction which were pioneered in these processes have promoted the extension of hydrometallurgy into other applications. Periodically, new tools such as solvent extraction, resin ion exchange, and flocculants have opened new avenues to hydrometallurgists. Conversely, pursuit of more complex mineralization, the rising costs of energy and environmental quality preservation, and declining ore grades continue to create new challenges. For much of this century, it can be fairly said that practically any hydrometallurgical development moved the frontier of technology. The 1970's and 1980fs, however, have seen a significant maturing of hydrometallurgy's role in process metallurgy. Simplistically, this maturing seems to derive from a growing awareness of the strengths and weaknesses of hydrometallurgy and a determined effort to capitalize on the strengths. For example, many of us were among those revolutionaries of the 1960's and 1970's who taught that "chemical smelting" was the answer to the treatment of all sulfides. We now recognize, however, that only in very special cases can hydrometallurgy offer economic advantage over the generally less energy-intensive pyrometallurgical systems. The maturing of hydrometallurgy does not, however, signal stagnation. Important innovations are being studied and developed in most extractive areas, and a number are approaching or have achieved commercialization. From our company's perspective, that of an organization dealing with the development of the most economic solutions to metallurgical problems, innovation must be defined as the commercially successful reduction of an idea to practice. There appears to be no shortage of ideas, nor has there ever been a shortage. Many ideas now being implemented were conceived decades ago, but reduction to practice was foiled by the lack of such technology as responsive process control and economical materials of construction capable of withstanding highly corrosive or erosive environments. Commercialization of a new process is a particularly challenging undertaking. Even if technical risks are reduced to a minimum through careful and thoughtful process development, there are inevitable uncertainties in feed characteristics, variable costs, and product prices. Commercialization takes courage, both on the part of innovators who may be staking their careers or reputations and of investors who may face financial disaster in the event of project failure. This paper discusses innovative programs and recently commercialized processes which either have been discussed in the literature or disclosed to Hazen Research staff in private nonconfidential conversations with contacts in industry. Regarding this latter category of information, relative ease of communication has resulted in many of our observations being of North American origin.

Jan 1, 1985

By Thomas J. Peters

At the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines and U.S. Geological Survey conducted a mineral investigation of about 85,470 acres of the Diablo Mountain Wilderness Study Area, to determine mineral resources and mineral resource potential. The study area is in Lake County Oregon, about 45 miles northwest of Lakeview. Fieldwork was conducted in 1986, 1988, and 1989. Geologically, the study area lies on the northwest edge of the Basin and Range physiographic province, a region of fault block-formed mountains and basins characterized by interior drainage. Consolidated rocks are mostly Tertiary basalt and tuffaceous sedimentary rocks. Low-lying areas are covered by Quaternary alluvial-fan, sand-dune, playa, lacustrine, and landslide deposits. The principal structural features are normal faults that have large vertical offsets; these faults are typically concentrated at the margins of large horst and graben. The 34,310-acre "additional," or western part of the area was mainly studied in 1988 and borders the east shore of saline Summer Lake. In this portion of the study area there is potential for undiscovered resources of soda ash, boron compounds, and sodium sulfate as well as by-products, which include magnesium compounds, salts, potash, bromine, lithium, and tungsten associated with brines. No energy or mineral resources were identified in the study area, but brines within lake and playa sediments contain concentrations of chemical components suitable for the production of soda ash, boron compounds, and sodium sulfate. Possible by-products include potash, salts, bromine, lithium, magnesium compounds, and tungsten. Limestone from the study area could be used in the recovery process of brine components or agricultural uses. The study area includes thermal springs and lies within 2 miles of the Summer Lake Known Geothermal Resource Area. Local production of geothermal power by the binary process may be economically feasible. Soda ash, soda ash products, and boric acid are widely used in fluxing metals, and have important applications and markets in the aluminum industry in the northwest and the developing Chinese counterpart. Evaporite commodities are essential to many "backbone" industries, and to many new applications and advanced materials. Markets for brine mineral products appear to be undergoing steady and strong growth, especially in the Pacific Northwest and in Pacific Rim countries. Soda ash produced near the study area would be 55 percent closer by rail to marine export at Portland, Oregon, than trona deposits of the Green River District (Wyoming). Soda ash and a daughter product, caustic soda, and sodium borohydride will receive increased application in the bleaching of paper pulp for environmental reasons. Caustic soda, used in many industrial processes, is more environmentally friendly when derived from soda ash than when produced from sodium chloride salt, because of the absence of a chlorine by-product. Producing soda ash from brines, a type of in situ" mining, can be done with minimal environmental degradation, and mining natural soda ash is environmentally as well as economically preferable to synthetic soda ash production.

Jan 1, 1995

By J. A. Baicker

A 2 1/2 inch diameter probe containing a high resolution gamma ray spectrometer was developed for downhole ore grade assays to depths of 6,000 feet. Tests have been conducted on the characteristics of this tool for in-situ determinations of uranium by means of natural gamma ray counting, and of copper, silver, gold, iron and coal quality by means of neutron-induced gamma rays. Application of the technique for improved carbon-oxygen logging in oil fields is promising. The probe contains a cryogenically cooled high purity germanium detector and a 4,000 channel spectrum analyzer. Gamma ray spectra are digitally transmitted up the cable to the truck-mounted data processing system. We found that uranium can be assayed directly in different types of formations independently of the degree of geochemical disequilibrium by counting the relatively weak 1.001 MeV gamma ray of protactinium-234m. Neutron activation work shows that in-situ determinations of copper, silver, iron and coal quality are technically feasible. In carbon-oxygen oil well logging the technique allows an accurate determination of carbon, oxygen, hydrogen, chlorine, silicon, calcium and iron, and shows promise of providing an improved oil/water differentiator.

Jan 1, 1982

By A. E. Koski

This paper describes the implementation of specialized software in mine planning at the Cleveland-Cliffs' managed Empire Mine on Michigan's Marquette Iron Range. The application puts together years of mining experience on the eastern end of the Marquette Range beginning in the early 1960's. The Empire Mine, in its thirty-fifth year of production, uses the software to model a complex and highly variable low grade magnetite ore body, capturing the economics of mining and processing to the final product. With special attention given to geostatistical methods, the software is used for all geologic modeling, ore reserve estimation, ore control, pit design and short and long range planning.

Jan 1, 1999

By Daniel R. Walton

This paper covers several points of interest to mine engineers and planners involved in evaluating or conducting geostatistical coal reserve estimates. In particular, the ability to optimize borehole drilling locations and minimize drilling costs is addressed. Also discussed is the concept of confidence intervals for estimated coal characteristics obtained through geostatistical estimates and their importance in decision-making for mine planners. Finally, a discussion is presented on how geostatistics enables identification of invalid data points and actually forces strict attention to data editing and proper geologic interpretation.

Jan 1, 1982

By Eric Hansen, Todd Wanless, Chris Mueller, Shannon Dunne, Scott Elmer

Between 2010 and 2018, Houston added more than 1 Million residents; the third largest rate of growth in the nation. With growth, the region faces new challenges with water supply, capacity of its wastewater system, and regional drainage. While tunnel construction has been limited in Houston since the Clean Water Program of 1990s, it is about to see a resurgence to improve water supply reliability and to reduce flood risks and sanitary sewer overflows. This paper examines the challenges with “going deep” below the built urban environment and related to high ground water; stiff, fissured clays; flowing silts and sands; faults; hazardous materials; and abandoned well fields.

Jun 13, 2021

By James P. Savely

This paper describes the development of a trim blast design to improve the stability of a final pit wall. Description is given of the effects of rock characteristics, rock type, and pit plans on the blast design. Currently, six benches have been mined with trim blasting. A more stable final wall has resulted and the successful program has reduced mining costs over an extended time period. Low cost blast monitoring and field observation were used to determine peak particle velocity and blast damage. Using criteria developed from this relationship, trim blasts were designed and evaluated.

Jan 1, 1986

By Tim O’Neil

Big and getting bigger. Barrick Gold Corp., the third-largest gold producer in the world, began production in September — ahead of schedule — at its Meikle Mine. At a scheduled full production rate of 12.4 t/a (400,000oz/year), it will be the largest producing underground gold mine in the United States. The $180-million Meikle Mine is located on Barrick’s Goldstrike property in Nevada and has 205 t(6.6 million oz) of gold reserves. The compact Meikle deposit has an average ore grade of 23 g/t (0.68 oz/st), making it one of the highest-grade mines in the country.

Jan 1, 1996

By W. Douglas Gould, Mei-Lin K. Stichbury, Jeffrey G. Bain, Blowes David W.

The mechanisms of release of arsenic in gold mine tailings were investigated. The highest concentration of dissolved As (75 mg/L) was observed near the base of the tailings impoundment, in close association with a peat layer. Elevated concentrations of reduced iron and hydrogen sulfide were also measured at the base of the impoundment. High numbers of iron-reducing and sulfate-reducing bacteria were detected at depths within the impoundment which correlated with dissolved As, Fe and H2S. The data presented in this paper suggest that arsenic is released from the tailings by bacterially-mediated reductive dissolution of As-bearing iron minerals.

Jan 1, 2000

By N. S. Tanious

Retrievability of emplaced nuclear waste from the geologic repository is a performance objective imposed by Federal Regulations. This requirement is designed to provide confidence in the Department of Energy's repository design by keeping the option of retrieval open if the engineered or natural systems prove inadequate for containment and long-term isolation of high-level nuclear waste. This paper presents a summary of current Nuclear Regulatory Commission Staff thinking on the design of the repository for retrieval, and level of retrievability demonstration that may be required during site characterization. However, this paper does not represent official U.S. Nuclear Regulatory Commission position on this topic.

Jan 1, 1989

By M. D. Scott

Lornex Mining Corporation operates an open pit porphyry copper mine in the Highland Valley southwest of Kamloops with a rated capacity of 43 500 TPD (48,000 TPD). It went into production in April 1972. Its concentrator consists of two grinding and flotation circuits in parallel each composed of a 6 000 KW (8,000 HP) 9,75 m (32 foot) diameter by 4,724 m (15'-6") semi-autogenous primary mill feeding two 3 000 KW (4,000 HP) 5,029 m (16.5 foot) diameter by 7,01 m (23 foot) secondary ball mills each feeding a bank of flotation cells. ,The original tailings system picked up the tailings from the flota¬tion circuits in a concrete collection box in the mill and carried the 36% solids density by weight slurry 488 m (1,600LF) through a 1100 mm (42 inch) diameter wood stave pipeline on a .46 percent slope to three 99,06 m (325 foot) diameter center drive thickeners. From the collection box under the thickeners the tailings line con¬sisted of three sections, carrying 50% solids density slurry. The first section consisted of 1460 m (4,800 LF) of 910 mm (36 inch) asbestos cement pipe for gravity flow from the thickener under flow elevation of 1252,4 m (4,109 feet) to the first pump station at elevation 1207,6 m (3,962 feet). Eight concrete drop boxes were used to limit the maximum slope on the pipeline to 0.5 percent.

Jan 1, 1976

By W. A. Rickelton

The first commercial use of phosphine derivatives as solvent extraction reagents began in the mid 1970's with the construction of several plants to recover uranium from wet process phosphoric acid. The process eventually adopted by all of these plants used the well known trioctylphosphine oxide (TOPO) in synergic combination with D2EHPA to extract U(6+). This prompted the development of other phosphine - based reagents and led to the discovery of a variety of interesting commercial and potential applications which are summarized in this paper. The applications include cobalt-nickel and niobium-tantalum separation and the selective recovery of silver and zinc.

Jan 1, 1994

By F. G. Miller

To improve coal flotation Bethlehem Steel Corporation's Research Department has been working on a number of related problems based on both physical and chemical factors. The ideal is of course full understanding of the interrelated effects of both sets of factors. However, detailed studies5 of each physical factor have produced immediately usable results in commercial coal flotation and are providing the bas is for our current work on the effect of chemical factors. Since these detailed studies provided the basis for the present investigation of froth sprinkling, their key results are highlighted here. For example, for a highly floatable bituminous coal, particle floatability was shown to be directly related to the percentage of coal surface available for bubble attachment and inversely related to particle mass. The data also underscored that in a given size range the addition of mineral matter to a particle makes flotation more difficult both by adding to the mass of the particle and by decreasing the amount of coal surface available for bubble attachment. Size also affects particle floatability in that as the size of particles of a given specific gravity increases, mass increases and the ratio between coal surface area and mass of the particle decreases. Flotation tests showed that any recovery of the coarsest particles in a coal feed is accompanied by progressively higher recovery of finer and finer particles. Consequently, fine high-specific-gravity particles are recovered with the coarse good coal. As a result, when the entire 14M x 0 size range is processed by froth flotation, the good coarse coal is contaminated with high-specific-gravity fines. It is the small quantities of these fines that must be rejected from the froth product if flotation efficiency is to be increased above its present level.

Jan 1, 1968

By Sibley C. Burnett

Early attempts to apply superconductivity to the beneficiation of kaolin required very large refrigerators to remove the heat generated during rapid charging and discharging of the magnet. In the early 1990's, Advanced Cryo Magnetics, Inc. developed and patented methods to reduce this pulsed heating by a factor of fifteen. Small, helium refrigerators and cryo-coolers are now used. Along with savings in electric power, superconductivity allows operation at higher magnetic fields and greatly improves separation process efficiency. New designs offer enormous reductions in weight, size and capital cost as compared to older copper magnets. Application of this technology to minerals other than kaolin is emerging.

Jan 1, 1999

By D. J. Barratt

What is meant by "Minimizing Risk"? This paper explores some of the factors encountered in plant design which can affect the success of a mineral processing plant in terms of its planned output, quality of product and recovery. Any deficiency in either one of these objectives means lost revenue at the start of a project and reduced present value for the mine life. Time is money. Related factors such as project conception, feasibility studies, capital cost and operating cost estimation and mining studies have been covered in a recent paper (1) from which material for this paper has been drawn. What follows is a discussion of the principal factors which can influence the success of a project with particular emphasis placed on processing concepts.

Jan 1, 1983

By E. W. Sawyer

Attapulgite is a magnesium aluminosilicate clay mineral which exhibits unique, processing-enhanceable physical and chemical properties that are related to its current commercial uses. Properties of commercial interest are gelling, absorption, adsorption, binding, acid neutralization and many others. Major industrial applications are: (1) absorption by heat treated grades utilized in industrial oil and grease absorbents and in agricultural pesticide carriers; (2) gelling of aqueous liquid products by colloidal grades for stabilization and viscosity control in salt water drilling fluids, suspension fertilizers, liquid animal feed supplements, paints and tape joint compounds; (3) adsorption by heat treated varieties for the removal of catalysts, color bodies and other polar compounds from hydrocarbon streams; (4) gelling of organic liquids by colloidal attapulgite/surfactant blends in oil-type paints, fibrated and nonfibrated asphaltic coatings and mastic compositions, and (5) the binding of feeds and molecular sieve sorpents with colloidal type attapulgite products. These applications and other less common uses and potential uses will be discussed along with, the necessary selective mining and plant processing features related to each property and application.

Jan 1, 1986

By Douglas J. Pendrell, Marvin D. Simmons, E. Raymond Boc

The U. S. Army Corps of Engineers is in the early stages of design for an estimated 14 m (46 ft) diameter tunnel in northeast New Jersey. This tunnel will carry flood waters from the upper end of the Pompton River in Wayne County, to an outlet in Newark Bay, a distance of 33 km (20.5 miles). The tunnel will be constructed by a tunnel boring machine (TBM), the size of which is unprecedented at the present time. The alignment is through Triassic and Jurassic sandstones, siltstones, and shales that include three beds of basalt that range in thickness from 76 to 310 m (250 to 1020 ft).

Jan 1, 1991

By John C. Braithwaite

Gold production commenced in New Zealand during the gold rush of 1861, and recovery to date is over 900 tonnes, almost 60% of which was alluvial. New Zealand pioneered development of bucket line dredges during the 1880's. The advent of the modern hydraulic excavator and increased gold price led to a resurgence in alluvial production with about one hundred plants in operation in 1988. The processing plants are mainly floating, with throughputs of 50-100m3/hr fed by backhoes of 20-40 tonne operating weight. Some larger plants with more sophisticated recovery systems have commenced over the last few years, with the largest using a 180 tonne backhoe.

Jan 1, 1989

By A. W. Fletcher

A nickel-copper sulphide concentrate was treated in a pilot plant at Warren Spring Laboratory during 1961, by a hydrometallurgical roast-leach- solvent extraction process devised to cleanly separate the metal values, and produce acid sulphate liquors containing the metals. It is shown that 86 percent of the nickel and 95 percent of the copper could be leached from the calcine, after a sulphatizing roast on finely ground flotation concentrate. Iron was removed from the leach liquor by limestone neutralization with a small loss of values. Copper and nickel were separated by solvent extraction with naphthenic acid in kerosene after partial neutralization of the iron-free liquors with ammonium hydroxide. Hydrogen sulphide and chlorine were used to remove zinc (and residual copper) and cobalt impurities respectively. The recovery of pure copper and pure nickel, by electrowinning, from the acidic solvent extract strip liquors finally produced, appears technically feasible.

Jan 1, 1964

By R. T. Swinderman

"Virtually every article you read on safety has a statement to the effect: “It’s obvious that safety pays”. If it is so obvious, why is it so hard to answer these questions? • How does the Maintenance or Operations Manager convince the Plant Manager to spend money from the annual budget for safety improvements? • How does the Plant Manager influence Corporate to prioritize safety improvements? • How does an engineering firm persuade the owner to spend more on design and equipment up front to reduce risk? There are many cultural and structural reasons why it is so difficult to prove the obvious. In my opinion the main culprits are: the almost universally used ‘Low Bid’ process, variations in reporting incident statistics between industries and countries, and, the Generally Accepted Accounting procedures (GAAP) [or International Financial Reporting Standards (IFRS)]. Conventional wisdom is it’s smart not to spend more than you need to meet the minimum regulations and maximize production. But buying on price alone often harms people, degrades the environment, and reduces the company’s bottom line. How can this be? You met the minimum safety requirements and saved money by buying on price. Don’t those savings go right to the bottom line? When you buy on price you get minimum quality, minimum compliance and are often backed corner with no reasonable options to rectify the problems that arise from buying on price instead of buying on long term life cycle cost. Culturally few companies actually ‘walk the talk’. It is trendy to have giant billboards at plant entrances proclaiming world class compliance with quality and safety standards. Annual reports are embellished with safety slogans and sustainability statements. Behind the front gates and the glossy annual reports the message is clear: produce or be replaced. Only a few companies go beyond the window dressing and actually endorse, from the top down, continuously improving their safety culture. Those that do embrace safety, show significant performance advantages over their competition that are reflected in their safety, productivity and environmental records and, ultimately their financial statements and share price. Current accounting (and reward) systems make it unlikely financial managers will accept non-conventional approaches to justifying expenditures on safety because they are driven to report “hard” numbers that can be documented and are within the “GAAP or IFRS Rules.” But in reality, accountants quantify soft or intangible costs all the time in their financial statements. Justifying safety investments is greatly enhanced by quantifying what most financial managers would call intangible costs. Government agencies have no problem assigning intangible costs to justify regulations to improve safety. How many times have you heard that the regulation is justified because the cost to industry is X while the benefit to the society is 2 or 3X? How can they say that without including intangible costs? We find it hard to believe these government claims of benefits to society because we have been trained to think about saving hard direct costs to justify investments."

Jan 1, 2017