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By K. J. Sollman

As a class, silicate minerals have likely found the broadest, if not largest volume, use in combination with polymeric binders of all industrial minerals. Among the silicates, calcium metasilicate, wollastonite, enjoys a front runner position in a near universal sense. It is a viable and desirable part of composites ranging from thin films to large moldings; from a common filler/extender for paint for your garage to a reinforcement for the exterior surfaces of a luxury vehicle affordable to very few. This article is focused upon the variations in particle morphology and the surface characteristics which, by way of commercial examples and discussion of active research programs, make this environmentally benign mineral so unique.

Jan 1, 1993

By C. D. Harrison

This paper presents the results of 18 high-G centrifuge tests performed at the Electric Power Research Institute's Coal Cleaning Test Facility in January 1985. These tests, using -28 mesh (0.6mm) froth flotation product, show that the high-G, solid-bowl centrifuge can produce clean-coal moistures of less than 12 percent at solids recovery rates exceeding 98 percent. The high-G centrifuge achieved these low moistures by applying centrifugal forces up to 2,000 times gravity. Because these forces are two to three times the forces used in a screen-bowl centrifuge, the high-G centrifuge can use a solid bowl and still produce a low-moisture product. The solid bowl captures ultrafines that would pass through a screen bowl, and thus obtains higher recovery rates than a screen-bowl centrifuge.

Jan 1, 1985

By J. P. Hedlund

Molycorp's gravity type panel-caving operation employs a system of short raises to transfer ore from the Grizzly Level to the Haulage Level. The raises have normally been developed using a conventional drill-and-blast method or a combination conventional/raiseboring method. A new method was needed that would be less labor intensive, provide a safer work environment for personnel, provide a stable raise that could be self-supporting and a method that would be cost competitive with the conventional system.

Jan 1, 1991

By J. Fuller, L. Marsden

Windborne dust from alkaline salt flats and mining-related tailings ponds is especially prone to threaten applicable ambient air quality standards. Sodium carbonate crystals, typically present, weather to an exceedingly fine, non-cohesive dust, causing air quality problems for miles downwind. Recently developed specialized polymers react with alkaline dust to form sturdy, wind-resistant crusts with good longevity. An on-going demonstration project at a major trona facility has developed techniques for cost-effective application of these polymers over large areas of soft tailings or sediments in a wide variety of situations. Recently treated areas on the order of 80 acres show effective suppression of dust.

Jan 1, 2004

By Robert L. Sundeen, Richard V. Wenberg

INTRODUCTION Shotcrete can be defined as spray-applied concrete with a maximum size aggregate in excess of 9.5 mm (0.375 in.). The concept evolved from guniting, which uses smaller aggregate and generally produces concrete with poorer physical properties. The larger aggregate used in shotcrete requires less water in the mix, while offering larger bonding surfaces, thus imparting greater tensile and compressive strengths. TYPES OF MACHINES Two basic designs of shotcrete machines in general use are the wet or prehydrated zero slump and low slump type, and the dry or nozzle hydrated machines. Fig. 1 shows a typical zero-slump machine in a con¬figuration commonly used for small-volume require¬ments. The prehydrated zero-slump machine mixes exactly proportioned batches in a sealed pressurized chamber. "Slugs" of hydrated shotcrete mix and com¬pressed air are sent through a distribution hose to the nozzle where the wet mix emerges as a spray. The spray is directed onto the rock surface by the nozzle operator. The low-slump machine is similar, except that a thick slurry mix of aggregate is delivered throughout the distribution hose to the nozzle. Fig. 2 shows a typical low-slump shotcrete machine used in moderate-volume applications. The nozzle-hydrated shotcrete machine accepts a premixed "dry" (4 to 6% moisture) batch of aggregate and cement. A constant feed of this mix is directed by compressed air through the distribution hose to the nozzle. At the nozzle, water for hydration is introduced into the emerging spray. The hydrated mixture is di¬rected onto the rock surface by the nozzle operator. Fig. 3 shows a typical dry-mix machine. The major difference between the two basic machine designs is the consistency of the shotcrete quality. Pre¬hydrated machines have high degrees of consistency and produce high-strength concrete, resulting from their ability to produce exact mixtures of zero or low-slump concrete within the machine. Nozzle-hydrated machines tend to produce poorer quality concrete because of the difficulty in controlling the water content at the nozzle. Water input essentially is an art. As such it is not precise, and the shotcrete produced is of variable quality. MATERIALS HANDLING Materials handling presents a problem to either type of shotcrete machine. At times considerable quantities

Jan 1, 1982

By Thomas P. Kwiatkowski, Len Cobb, Christopher D. Orlandi, Judith H. Jones

The Inland System supplies raw water to the industrial and domestic users in the City of Birmingham, Alabama. The Inland System, which is nearly 60 years old, consists of an approximately 57.9m (190 feet) high earthen dam across the Blackburn Fork of the Black Warrior River, a 39.6m (130 feet) high reinforced concrete intake structure, a 1524mm (60inch) diameter Dresser coupled steel transmission pipeline, and various distribution lines extending into Birmingham. The Inland System was owned, operated and maintained by the Industrial Water Board (IWB) of the City of Birmingham, an agency of the city government, from 1958 until 1994. In 1994, the City of Birmingham consolidated all water and distribution functions under the Birmingham Water Works Board (BWWB). In 1988, the IWB determined that the Inland System had reached a point where its reliability could not be assured without an in-depth evaluation and renovation. The IWB engaged Christy/Cobb, Inc. (CCI) of Birmingham as its consultant for the renovation work. CCI evaluated the Inland System and submitted a report to the IWB in April, 1992. The report contained several recommendations for capital improvements to the system including increasing the emergency spillway capacity, reconstructing the fuse plug, relocating public access to the lake away from the dam area, constructing a new intake structure, and constructing a tunnel through the dam abutment to deliver the water from the proposed intake structure to the existing 1524mm (60 inch) diameter supply line. The new intake structure and tunnel would provide for a future maximum demand flow rate as well as provide bypass and level control capabilities. CCI was authorized in 1992 to proceed with the engineering design for the renovation of the Inland System with emphasis on the spillway and intake structure. PROJECT DESCRIPTION The major component of the renovation of the Inland System was the new intake structure and tunnel through the dam abutment. CCI engaged Jenny Engineering Corporation (JEC) of Springfield, New Jersey as a consultant for the tunnel design. JEC was responsible for the design of the tunnel, the connecting shaft between the intake structure and tunnel, and the steel pipe final lining, while CCI was responsible for the intake structure and the connection to the existing supply pipeline as well as overall project management. CCI and JEC evaluated the project site in order to select the location for the new intake structure and set the alignment for the tunnel. A factor in the evaluation process was that the level of the lake could not be lowered to construct the new intake structure since the supply of water from the Inland System had to maintained. Therefore, a location was required which was

Jan 1, 1997

By Frederick J. Hoppe

The productivity or usefulness of a Front End Loader rises rapidly with its size. Loading is more aggressive. Mother Nature is defeated more easily. Larger tires get a better grip on the ground. Hauling equipment can be loaded more quickly. The productivity or usefulness of a Front End Loader is proportional to its working speed, both automotive and hydraulic. The price of speed is horsepower, which rises rapidly with speed. Horsepower saved shows up as increased productivity. This paper covers the development of the D600, KW-Dart's articulated loader, which combines massive size with new concepts to increase its working speed. Featured is a discussion of the horsepower saving, "Balanced Boom."

Jan 1, 1969

The mining industry is one of the three pillars of the Namibian economic development, besides tourism and the fishing industry. Generating 20 % of the GDP and more than 50 % of the export income, half of this amount derives from the diamond mining industry. In 2008, the annual production of 2.2 mio carat achieved an income higher than 1.44 billion Namibian Dollars (more than 750 mio Euro). After the global recession in early 2009, which also caused a significant downcrease in production to only 0.93 mio Carat, the diamond mining industry easily restored itself and the production figures for 2010 are expected to be even higher than those achieved in 2008. Compared to other diamond producing countries, Namibia is mainly producing diamonds of highest quality (jewellery quality), with less than 10 % of the mined diamonds not falling into this category. This high quality stands also for the worldwide highest prize achieved per carat. With 370 $US per carat it is more than four times higher than that of the average South African stone. In 1908 the finding of the first diamonds in the Namib desert close to the coastal town of Lüderitz was reported by a Mr Stauch, railway inspector for the then German colonial railway company. This event immediately triggered a Diamond Rush and subsequently the set-up of the restricted diamond mining area ?Sperrgebiet? through the German colonial administration. In 1913, only five years after the first mining operations had started, the steadily increasing production allowed for more than 20 % of the diamond production worldwide. After the First World War, the new South African government concentrated all mining activities in one organization, CDM (Consolidated Diamond Mines of South West Africa) which in following decades conducted an extensive and detailed exploration of the whole Sperrgebiet and started numerous new diamond mining operations.

Jan 1, 2011

By V. F. Swanson

A mathematical model for free and hindered settling of minerals was developed. This paper describes how to apply the model in designing systems, such as fluidized bed, elutriation, mixing pumping systems, involving solids and fluids.

Jan 1, 2000

By T. Foster

The continuous operation of decanters in the mining industry relies heavily on the use of synthetic flocculants. Today, as plants seek to lower production costs by increasing throughput it is necessary to obtain optimum performance from the flocculant. Factors affecting such optimization include charge and molecular weight selection, and efficiency of mixing the highly viscous polymer solution with the feed slurry. Beyond maximizing dilution of the solution, the last factor is often ignored. This paper describes a series of calculations, based on fundamental transport theories, that have been used to describe flow conditions within decanter feed wells and to help select flocculant addition points. Examples are shown for the case of hydroxamated polyacrylamide flocculants in the Bayer Process, where proper selection of the addition points can result in lower flocculant dosage and better control of the decanters.

Jan 1, 1996

By J. G. Groppo

Hyperbaric filtration was evaluated at the laboratory scale for dewatering fine coal cleaned by froth flotation. A laboratory pressure filtration procedure is described to obtain uniform cake structure from dilute slurries containing a significant amount of coarse material. Baseline tests were conducted varying filter operating parameters such as driving force, time, cake thickness, percent solids, viscosity and pH to determine optimum operating conditions for eventual application on a continuous pilot scale hyperbaric filter.

Jan 1, 1994

By Tanya J. Gallegos, Mojisola A. KunleDare, James V. Jones III, Charlotte E. Riggs

The United States Geological Survey (USGS) provides scientific information for the Department of Interior and the nation, consistent with its original mission expressed in the Organic Act of 1879 (43 U.S.C. 31): “the classification of the public lands and examination of the geological structure, mineral resources, and products within and outside the national domain.” Legislation such as the Energy Act of 2020 and the 2022 Infrastructure Investment and Jobs Act (43 USC 31l) and recent executive actions (Executive Orders 14154 , 14153, 14241 Secretary’s Orders 3417, 3418, 3422, 3436) underscore the importance of mineral resources and focus USGS activities on mapping and assessing mineral resources, with a particular focus on those presently identified as critical, both in ground and above ground in mine wastes. This article reviews selected activities and accomplishments by the USGS Mineral Resources Program related to critical minerals in 2025. Highlights include a new List of Critical Minerals, a first-ever national mine waste inventory, international minerals partnerships, mineral resource assessment advancements, and national data collection activities and outcomes of the Earth Mapping Resources Initiative (Earth MRI). The selected contributions are not comprehensive but are intended to demonstrate USGS leadership in critical mineral mapping and assessment, the importance of domestic and global partnerships, and the breadth of research activities that are responsive to national needs and priorities.

May 1, 2026

By William Kohan

The industrial grinding process has undergone changes to better address the market and economic needs. Fine grinding of dry materials has developed to the point where classifying linings and fine ball charges improve mill efficiencies. Roller mills as well have wide acceptance due to their power efficiencies. The mill, by its nature, cannot provide the specific particle size or range of sizes which are required for further processing or final use. Therefore, various separators are operated in conjunction with the mill to control particle size. The sizing device helps minimize over grinding and control top size. Rising energy costs combined with increasingly tighter quality specifications have led to increasing study of the grinding and separation process.

Jan 1, 1985

By S. B. Castor

Although production generally satisfies demand for rare earths, new markets may make undeveloped resources, particularly those rich in yttrium, more interesting. A Precambrian carbonalite orebody at Mountain Pass, California, has been the world's largest rare earth producer. Minor rare earth production comes from titanium placer mining in Florida and uranium mining in Canada. Prior to operations at Mountain Pass, North American production was mostly from placer deposits that constitute large, low-grade rare earth resources. Newly discovered North American rare metal resources in peralkaline igneous rocks are potential yttrium producers. Most of these resources are in a continent-wide belt of anorogenic magmatic rocks approximately coeval with mineralization at Mountain Pass. Other untapped rare each resources in North America are generally light rare earth-dominated and small or of low grade.

Jan 1, 1991

By David Kress

Grinding mills, both autogenous and ball can be powered by several basic means. The three methods used today are girth gear drives, gearless drives and trunnion coupled reducers. This paper will focus on the first of these methods -girth gear drives. The girth gear drive has been used on thousands of mills which continue to operate successfully. These drives are noted for their simplicity and low cost. In the past, the horsepower capacity of girth gears has been slow to keep up with the horsepower increase required by the mill builders, particularly since the advent of the SAG mill. Gear manufacturers had capacity for 2000 HP mills in the 1950's, 5000 HP in the 1960's and 6500 horsepower in the 1970's. The 70's and 80's brought dual pinion girth gear drives which allowed mill sizes beyond 10,000 horsepower. Gear manufactures who could not keep up with the pace of the horsepower demands and the quality and reliability demanded by the mill builders and users have fallen by the wayside.

Jan 1, 1991

By Richard Giffen, Boris CARO VARGAS, Terrence Carroll

"This paper takes an in-depth look at the $72 million design-build Norris Cut project, which includes the replacement of an existing 54-inch waste water sewer main to Fisher Island under the Norris Cut Channel. Tunneling through one of the country’s most unpredictable geologies created unique challenges in both the design and construction phases of the project. The paper presents the geotechnical and structural design considerations for the 100-foot deep secant piled TBM launch shaft in the highly permeable Fort Thompson formation limestone and sands. The structural design effort also included the design of the tremie slab, thrust wall and design of the largely unreinforced launch shaft to resist asymmetric loading from partial ground freezing. The retrieval shaft was designed as a deep soil mixed shaft and is thought to be the deepest soil-mixed shaft in Miami. From a construction perspective, this paper discusses the unique challenges of building two shafts with two different techniques and will compare some of the constructability aspects, costs and equipment schedule-considerations related to the use of two separate techniques. INTRODUCTION Nicholson Construction Company (NCC) was awarded a $72.1 million Design-Build contract to replace an existing force main from the Virginia Key Central District Wastewater Treatment Plant (CDWWTP) under the Norris Cut Channel to Fisher Island. The location of the project is shown in Figure 1. The project involves replacing an existing 54-inch diameter pre-stressed concrete sewer force main with a 60-inch diameter fiberglass force main. Arup USA, Inc. (Arup) is the lead designer for Nicholson on this design-build project. Arup is providing design services for the TBM launch and retrieval shafts, segmental tunnel lining, the fiberglass pipe, and the horizontal directional drill component. Miami-Dade Water and Sewer Department currently owns and operates the existing 54-inch sanitary force main that transmits sewage collected from Miami Beach and Fisher Island to the CDWWTP for treatment and disposal. The existing force main was subject to a condition assessment in December 2011 which revealed structural deficiencies in the pre-stressed concrete pipeline."

Jan 1, 2016

The effect of the chemical composition of pulverized bituminous coal particles on their physical transformation during the initial stages of combustion has been investigated. The results suggested that cenosphere formation does not require extensive thermal decomposition of the coal particles. The vitrinites in the bituminous coal softened earlier and developed larger cenospheres than the othe macerals. The coal particles swell to a higher extent during combustion than in pyrolysis; however, the cenospheres formed in the former process experienced a higher extent of fragmentation. The development of microporosity occurred predominantly after the resolidification of the swelled char particles. The type of macerals originally in the coal did not significantly affect the microporosity of the chars. Conversely, the morphology and anisotropy of the chars were strongly dependent on the maceral composition of the coal.

Jan 1, 1986

The effects of additives, sodium hydroxide, sodium carbonate, sodium oleate, oleic acid and polyacrylic acid, on stirred media milling of limestone have been investigated. The results are evaluated in terms of specific surface area, specific energy and energy efficiency as a function of additive dosage, polymer molecular weight, solids concentration and relevant operating variables. Use of additives generally results in changes in specific surface area and energy efficiency, while under certain conditions a more than 100% increase in these parameters can occur. Relevant interfacial properties have been measured and milling mechanisms involved are explored particularly in terms of the effect of additives on the flow patterns at higher solids concentration.

Jan 1, 1996

By Jim W. Rosteck, Anthony Del Vescovo

In December of 1992, the City of New York, Department of Environmental Protection, solicited bids for Contract 543B. The low bidder was a joint venture of Schiavone Construction Co., Inc. and the J. F. Shea Co., Inc. When completed, the project provides a 4.88 meter diameter water tunnel 8,840 meters long. This paper presents a case history of the equipment and construction methods utilized for this, the first portion of the New York City Water Tunnel constructed by use of a tunnel boring machine.

Jan 1, 1997

By Erich U. Petersen, Robert B. Coleman, William J. Tafuri, Donald M. Hausen, P. R. Taylor, Douglas N. Halbe, D. W. Rodolff

The definition of refractory gold ores and concentrates, including mineralogical characteristics, is reviewed. The chemistry of roasting and process conditions such as feed size, temperature, and time are discussed. A typical metallurgical program for developing a roasting process scheme is presented. The application of various types of furnaces for roasting is described. Requirements for scrubbing off-gases to meet environmental air emission regulations, and general information regarding engineering design parameters for roasting are presented. Roasting is sound technology for processing refractory ores and concentrates, but it is essential that the metallurgy of each ore or concentrate is well defined before commercialization. A fluid-bed roaster is the preferred type of furnace for roasting. Environmental regulations for air emissions must be carefully addressed.

Jan 1, 1990