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By D. J. Tooker

For the next few minutes, I will be discussing a product and category that many people laughed at for years. The product is cat box filiers or commonly referred to by the brand name KITTY LITTER. This product was introduced in 1947 by Ed Lowe using the name KITTY LITTER. From 1947 to 1964 the product was sold mainly through pet shops. Starting in 1964, the grocery trade began to carry cat litters. From that point, the cate gory began a solid growth trend. Particularly in the '7O's, cat litter has experienced the same kind of explosive growth that has characterized the entire pet market. For example, in the twelve months ending 9/21/79, cat litter unit volume grew by 15% versus the previous twelve months. The basis for this explosive growth is easy to comprehend. The cat population itself is rapidly expanding, reflecting the changing life- styles of Americans. As famiiies grow smaller, there is room for a pet. As apartment and con dominim living shrinks living space, a cat fills the human need for animal companionship more efficiently. Table I illustrates current cat litter market factors and projects major trends into the future to conclude that the cat litter market will equal $205MM in 1985. With this dynamic growth defined, it was imperative that a company such as Lowe's that was totally devoted to the commodity-priced products, evaluate the opportunities for added- value product differentiation. This process was started approximately four years ago with a search for new cat litter products and other new product opportunities.

Jan 1, 1980

By G. E. McKelvey

A group of gold deposits in southeastern Ecuador, near the town of Zamora, have become the focus of intensive mining activity, due to their extremely high gold grade (unconfirmed reports of about 50 g/t or 1.4 oz per st, or more). The deposits at Nambija and other prospects in the district are hosted by a sequence of sedimentary and volcanic rocks that are present within a large xenolith orpendant within alkalic phases of the Jurassic Zamora Batholith. The xenolith, unknown in size, is composed of various island arc lithologies (limestones, shales, sandstones, tuffs and flows). All have been altered to some degree by skarn-hornfelde alteration assemblages. Mineralized areas appear to be localized within a linear zone containing tectonic and intrusion breccias that cross-cut a complex calcic skarn assemblage developed within the xenolith. Although the nature of the host rocks appears to have exerted some control on mineralization, the high-grade ore is concentrated along north-northeast trending breccias, faults and dikes that crosscut the flat-lying stratigraphy and skarn alteration as suggested by the strong linear trend of workings in the district.

Jan 1, 1991

By D. Tao

The presence of insoluble slimes in potash ore poses a serious processing problem to the potash industry. These insolubles must be removed prior to potash flotation because of their high adsorptive capacity for amines which are generally used as collectors in the subsequent sylvite flotation. This is usually accomplished by scrubbing of the ore in brine followed by hydrocyclone classification to separate slimes from the salt particles. Insoluble slimes that remain in the ore after the desliming procedure are depressed by reagents such as guar gum or starch during sylvite flotation. In this research, the feasibility of using GP clay binders to replace guar gum for potash flotation was investigated. Batch mechanical flotation tests were conducted with the potash samples provided by a leading potash company. It has been found that GP clay binders increased potash concentrate yield and recovery at the same product grade. Effects on potash flotation efficiency of flotation process parameters such as impeller rotation speed, slurry temperature, binder type, dosage and conditioning time have been investigated to establish the optimum conditions for flotation. Binder GP374G33 has been identified as the optimum substitute for guar gum as slime depressant in potash flotation.

Jan 1, 2008

By Josh Willhite, Seth Pollak, Ben Seling

The Long Baseline Neutrino Facility Far Site at the Sanford Underground Research Facility in Lead, South Dakota will house four large detector tanks located in deep underground caverns. Construction of the supporting infrastructure required for this project is no complete including installation of a waste rock conveyance system and drill and blast excavation of several supporting drifts and chambers. This paper will discuss the design and construction of these pre-excavation and early works elements, and the overall project schedule as it closes in on commencement of cavern excavation activities.

Jun 13, 2021

By Ali Ekrem Aritan

Exposure to hand-arm vibration (HAV) among the labor force in the mining industry can result in permanent vibration diseases such as behavioral disorders, visual impairment, osteoporosis, pain (mostly in the hands, wrists, and shoulders), circulatory system disorders, and malnutrition. In this study, the vibration exposure of excavator operators working regularly in 25 different natural stone quarries was measured. In addition, the relationship between vibration exposure and rock properties was investigated. Gloved and ungloved vibration measurements were performed and revealed that antivibration gloves reduce excavator operators’ vibration exposure by 7.10–25.95%. Samples from each quarry were characterized with rock mechanics tests. The correlations between the hand-arm vibration measurements and the natural stone physical–mechanical properties (uniaxial compressive strength, Shore hardness, Knoop hardness, apparent density and total porosity) were determined to be over 70%. One finding of the study was that the health risk in excavators cannot be reduced sufficiently by the sole use of antivibration gloves. Furthermore, the excavation of any rock with a Knoop hardness above 121 is associated with an 81% risk of HAV. To increase awareness of the danger of vibration exposure for natural stone miners, training programs should be provided, and technical and operational changes should be implemented.

By F. S. Knoll

Magnetic separation employing superconducting technology is now accepted within the Kaolin processing industry, proving the value of this technology and its ability to operate reliably even at the most remote site. Developments in superconducting magnet engineering, including cryogen free operation, combined with experience in mineral processing enables new forms of Wet and Dry superconducting magnetic separation to be developed. Applying the high magnetic force advantages at 5 T else available from such magnets to other materials is now a reality. High magnetic force mineral separating system developments are reviewed allowing the mineral processor to take advantage of a technology that is no longer confined to the laboratory.

Jan 1, 1997

By B. Akwasi Osei

The lack of metrics to assess clamshell formation dredgeability limits the ability of engineers to predict the dredgeability of compact material and increases the risks associated with clamshell selection. Research is needed to develop metrics for predicting clamshell dredgeability. The objective of this paper is to evaluate possible metrics to predict the dredgeability of compact aggregates by hydraulically actuated clamshell dredges. Data on cylinder pressures and displacements, motor current, bucket tilt and cycle time (CT) were collected from a dredge. Work done and motor energy, potential metrics, were computed and their suitability in predicting dredgeability evaluated. Data analysis shows that; there is no correlation between tilt angle and work done or motor energy; a low correlation between CT and work done, and a strong correlation between CT and motor energy. Work done is a better measure of formation dredgeability, than motor energy, as it shows lower variability. However, in difficult digging conditions, work done alone does not accurately predict dredgeability. This work shows that, it is feasible to use cylinder pressures and motor signals data to predict dredgeability.

Jan 1, 2010

By S. G. Sawyer

The Pittsburgh Safety and Health Technology Center (PSHTC) of the Mine Safety and Health Administration (MSHA) provides engineering and scientific support to the inspectorate personnel of MSHA. One of the Center's myriad roles is to assist in the investigation of mining accidents, especially those involving fatalities. Center personnel utilize forensics to help uncover the causes of accidents and to make technical recommendations on the prevention of future similar mishaps. To exemplify a typical forensic investigation, this paper documents the methodology used in determining the reasons for a boat sinking, which resulted in a double fatality on a mine company pond.

Jan 1, 1997

By E. J. Rogans, W. N. Cartner

Carbon technology has largely superseded filtration plants as the more acceptable gold recovery technology. This has, over the last two decades, provided a tremendous driving force for the development of new equipment. One of the main focus areas of this technological development is the development of effi­cient interstage screening systems. Several variations of exter­nal and internal screens are available, with the more recent shift away from air cleaned units to mechanically swept units. This paper discusses the development of one such mechanically swept interstage screen and how the development led to the suc­cessful implementation of a carousel type of CIP operation. The first generation Pump-cell emerged as a consequence of the success achieved with the mechanically swept NKM screen, The idea was to modify the screen to incorporate the functions of pumping, screening and agitation in a single drive unit, the screen generating sufficient lift for interstage slurry flow so that all contactors would be at the same level. This sys­tem was further incorporated as a high intensity modular CIP contactor, i.e. low slurry residence times combined with high carbon concentrations. A discussion on the kinetic gold adsorp­tion theory and its manipulation in the design of the pump-cell concept is discussed in a paper published in a previous Randol Conference< 1), Testwork carried out at Vaal Reefs proved the concept of the Pump-cell on a pilot plant scale<2), which resulted in the building in 1990 of the first large Pump-cell plant at West Witwatersrand Gold Mine designed to treat 340m3 of pulp per hour and , even though the plant operated successfully with respect to gold recovery performance, a few problems were experienced with the basic engineering design(3),

Jan 1, 1996

By Richard Campbell, Claire Pirona, MEHMET KIZIL, Ismet Canbulat, Stephen Giese, Ravindu Goonawardene, Edward Steed, Serkan Saydam

The Australian longwall mining industry spends millions of dollars per year on proactive and reactive ground consolidation applications across most of the operations currently in production. The design and effectiveness of the applications and products vary widely and are based predominantly on-site precedence or what were considered successful applications at other sites in similar situations. In the continual improve the effectiveness of how consolidation products are used and when by enhancing our knowledge of the mechanical properties of products used in underground coal applications and applying this increased understanding to geotechnical design. One of the current challenges to further developing more appropriate and accurate geotechnical design methods for consolidation activities is the lack of standardised materials testing and knowledge of rock mechanics data on in situ performance. The lack of industry standardisadesign of consolidation programs, with a reliance on experience-based guidance for rockmass consolidation design. consolidation products. The program was designed to provide the industry with a set of geomechanical property index tests and a data set that can be utilised by rock mechanics engineers as baseline information for product evaluation and engineering design. The laboratory work undertaken is critical to understanding the exact small-scale mechanical properties of these products and testing was carried out at Monash University for various states of curing of each product. Recognising that the speed at which a mixed product develops its desired properties to act as a support element in underground coal mines is critical to its serviceability. This paper presents the testing rationale proposed, the testing results, and a framework for how the data set can be used to improve the engineering basis for ground consolidation design, in terms of expected rockmass performance under various mining conditions and application parameters.

Jun 25, 2024

By Yoichi Shimada, Katsuyuki Nishida, Shinichi Takahashi, Yasushi Okada, Yohei Nakamichi, Kazunori Oshiro, Taichi Terui, Sigehiko Sugie

"Temporary retaining walls are ordinarily used for tunnel construction work conducted using the opencut construction method. Retaining walls in such instances are typically installed vertically. However, shoring (such as struts and king posts) is required to ensure the stability of retaining walls in cases of excavation work to depths that exceed approximately 4 m. A new design and construction method that focuses on the effectiveness of retaining walls that are installed on an incline was studied with the aim of improving construction workability by omitting shoring. The inclined braceless excavation support (IBES) method, which was developed for use with the inclined buttress method, requires no shoring, even for deep-open-cut construction work and can be applied to deep excavation work on ground with a high groundwater level. This method has been applied at six work sites in Japan in recent years. This paper introduces the IBES design and construction method and presents verification results based on the design method, a model experiment, finite element analysis, and measurements obtained during construction work.INTRODUCTIONBackgroundIn the past, temporary retaining walls used in open-cut construction work have been installed vertically, and shoring (such as struts and king posts) has typically been used to ensure the stability of these retaining walls when the excavation depth reached 3–4 m. However, shoring interferes with structures built within excavations and requires box-outs and penetration sections in the structures, as well as concrete joints that raise concerns about their impact on the watertightness and long-term durability of structures (Figure 1).Shoring also narrows the space available for conducting construction work and reduces construction work efficiency, and the installation and removal of shoring increases the construction duration and cost. As a result, there has been a demand for ways to reduce or eliminate shoring to improve the quality of structures and construction work efficiency."

Jan 1, 2016

By John Greenhalgh, Benoit De Rivaz

"1.INTRODUCTIONThis paper is based on the Lee Tunnel project, which is part of the Thames Water’s Tideway Project.The client Thames Water has employed a Joint Venture of Morgan Sindall/Vinci Grand Projets and Bachy Soletanche to undertake the design and construction of the project under the management of CH2M Hill at a value in excess of £635 million ($990 million). The 3 main elements of the tunnel project are the permanent lining to the shafts, the precast segmental lining, and the secondary tunnel lining. All 3 are reinforced with different types of Dramix steel wire fibers and each element will be described in this paper. This paper will explain the basic structural design of FRC (Fiber reinforced concrete) based on the post cracking residual strength and will describe all the steps of this project, the testing program realized to support innovative design and the main technical learning point. 2.BASIC CONCEPT OF STRUCTURAL DESIGN OF FRCStructural design of FRC elements is based on the post-cracking residual strength provided by fiberreinforcement. Other cases, like early age crack-control or fire resistance, are considered non-structural use of FRC. For structural use, a minimum mechanical performance of FRC must be guaranteed. Fibers can be used to improve the behavior at SLS (Service Limit State) since they can reduce crack spacing and crack width, thereby improving durability and they can be used to improve the behavior at ULS (Ultimate Limit State) where they can partially or totally substitute conventional reinforcement in most conditions. In the design process, the definition of the performance expected from the material is a key factor and the mix-design of the material has to be optimized for the required structural performance.2.1 Testing Method In order to ascertain the structural requirements requested for the FRC segments, preliminary testing on samples will be required and the effectiveness of the proposed solution will also be assured by the testing of full scale specimens. Structural design of FRC elements is based on the post-cracking residual strength provided by fiber reinforcement. For structural use, a minimum mechanical performance of FRC must be guaranteed. Nominal values of the material properties can be determined by performing a 3-point bending test on a notched beam according to EN14651 (figure 1) or by performing the ASTM C1609 beam test:"

Jan 1, 2016

By J. Stachurski, N. A. Abdel-Khalek

The objective of this investigation was to compare the results of countercurrent, column cell flotation vs. conventional (mechanical) cell flotation for the cleaning of a sulfur ore (-0.5 mm, 27.43% S) and its discrete size fractions. The tests were carried out using diesel oil as a collector and alcohol as a frother. Generally, column flotation produced concentrates of higher grade. For example, column cell flotation produced a nonwashed concentrate of 65.3% S with a recovery of 84.1%. However, conventional cell flotation produced a rougher concentrate of lower grade (57.0% S) and higher recovery (92.5%). At a superficial-wash water velocity of 0.265 cm/sec, the column product grade increased to 76.4% S, with a slightly lower recovery (80.3%). However, a concentrate with a similar recovery but a lower grade (74% S) than that of the washed product was obtained after three cleaning stages with the conventional cell. The column gave superior results for the flotation of fine and ultrafine particles.

Jan 1, 1994

By M. D. Monroe

Getting the best match between truck and haul road requires examination of many factors and their effect on the bottom line. Most mines use a bottom line measure based in some way on cost per ton of material moved. This measure focuses on the two components of truck haulage cost per ton: productivity (or performance) and operating cost. Productivity can be measured or predicted for specific tasks using either field measurement or modelling. Individual tasks can be combined to provide a larger scale, longer term net figure for total mine output. True cost is more difficult to capture as they are time and task oriented and can be influenced by a summation of factors over a truck lifetime. For example, "allocated" costs, such as owning (depreciation) and some repair costs, are spread over long periods of time. Other cost, such as fuel and tires can be tied more directly to certain tasks such as fuel and tire cost. This paper focuses on the more direct, task-oriented factors that affect truck productivity and cost.

Jan 1, 1992

By H. Burton

"The selection of the ultimate pit shell has a major impact on the overall value of a mining project. The size and shape of this pit drives the selection of pushbacks, equipment, and project strategy, each of which are significant in their own right. Optimization of the ultimate pit shape is typically done using the Lerchs-Grossman algorithm with inputs of production costs, commodity prices, and pit slope constraints. This method ensures that every tonne mined is profitable but does not take into consideration the timing of material release. This timing is essential when calculating the Net Present Value (NPV) of the project, which is one of the most popular metrics for valuing deposits. Often, when the mining schedule and discounting are applied, material that was considered profitable before discounting becomes sterilized. The objective of this paper is to show the methodology for improving ultimate pit selection by considering the production schedule. Application of this technique will generally produce a smaller and higher-value pit than using the Lerchs-Grossman algorithm alone. INTRODUCTION The Lerchs-Grossman Algorithm was developed in the 1960s and exists to produce a mathematically optimum shape for open pit mines (1). This algorithm is now an industry leading technique for producing the theoretical optimum shape for open pits and is used in many popular pit optimization and strategic planning software packages, such as GEOVIA’s Whittle. The Lerchs-Grossman (LG) Algorithm is based on graph theory and optimizes on the assumption of non-discounted cash flows. This produces a mathematically optimum shape, but does not consider the timing with which the material will be removed from the ground. This is an important consideration, given that one of the most popular metrics for evaluating mining projects is Net Present Value (NPV) (2), which relies on the timing of cash flows as a major differentiator between options. This paper will discuss issues inherent in the use of ultimate pit selection based on undiscounted economic factors and illustrate a simple technique in Whittle, a leading software package, which can be used to improve the NPV of projects."

Jan 1, 2015

By R. Miller

Lowering our globe’s emissions is a major effort as we move toward a future net-zero carbon environment requiring significant investment in a new, low-carbon infrastructure, along with key market incentives to change. Industry will play a key part in this transformation, requiring expertise in both energy and emissions. Key elements of the de-carbonization strategy are: energy data, emissions reporting method, governance, de-carbonization project generation and drivers, the MACC, electrification, and the de-carbonization checklist. For a zero carbon future, it will be key for business leaders to understand decarbonization, anticipate technological changes, and implement new business me

Mar 2, 2022

By Takayuki Sakai, Takefumi Takuma, Lee Roesner

"70-foot deep rectangular-shaped bulkheads were built with sheet piles as launching and receiving shafts for a pipe jacking operation for new underground waterlines in a densely populated section of Los Angeles, California. The Press-in Piling Method was specified to drive 95-foot long sheets (a record for the method) to form the bulkheads for the Los Angeles Department of Water and Power’s LA-29 (DWP) Connection Modification and Pipe Jacking. The piling was chosen because of its very low noise and practically vibration-free nature since the site is surrounded by houses, an apartment complex, and existing water lines. The out front areas of the bulkheads were grouted to let the TBM go through without major ground water leaks. Hydrophilic foam grout was also injected in addition to welding steel scab plates on the inside to seal them to achieve sufficient watertightness behind a few split interlocks. BACKGROUND This project was located in the Crescent Heights area of Los Angeles which is a few miles south of Beverly Hills. The project represents the completion of the last phase of the Stone Hollywood Trunk Line. This was an 8-mile long water trunk line that averaged 60 inches in diameter and was built to improve the reliability of the DWP’s major water system. This section of the project involved driving 2 deep shafts to allow for the installation of a 350-foot-long 72-inch steel casing using microtunneling construction. See Figure 1 for the shaft locations and the tunnel alignment. The challenge for the project was that this water line would have to pass beneath the Hollyhills buried box drain (15 feet high by 20 feet wide). Further complicating the construction was the soils beneath the drain. The DWP chose to drive the tunnel at a depth of approximately 65 feet to ensure that the ground conditions were uniform and suitable for the microtunneling equipment. There were two previous attempts to construct this work which failed because of poor ground conditions and very high water levels. This third attempt was critical because the DWP could not afford to have another failure due to the fallout with the residents being impacted by the project."

Jan 1, 2016

By R. David Williams

Old mine workings are found throughout the Western United Sates on lands administered by the U.S. Bureau of Land Management (BLM), U.S. Forest Service (USFS) and private lands. Some of these mine workings date back to the late 1800s. There may be as many as 100,000 sites on lands administered by the U.S. Forest Service and Bureau of Land Management. The Bureau of Land Management has worked with the State of Montana and other agencies to identify and prioritize these sites on BLM administered lands. Following completion of the AML inventory work, the Bureau began an aggressive program to clean up priority sites. This presentation will highlight completed work as well as work in progress on several sites.

Jan 1, 2000

By S. Veeramasuneni

The sign of the surface charge for alkali halides in their saturated brines has been established from non equilibrium electrophoresis measurements and on this basis the flotation response of alkali halides was explained based on the adsorption of oppositely charged collector colloids by heterocoagulation. These surface charge results for alkali halides are generally as expected from simplified lattice ion hydration theory with some exceptions, specifically LiF, KCI, NaCl, KBr, RbBr, KI, and Rbl .The presence of natural oxygen defect states in the crystal lattice and the inaccuracies involved in the gaseous ion hydration free energy values used appear, in past, to be responsible for these deviations. The presence of natural oxygen defect states in KCI, KBr, RbBr, and Rbl as characterized by UV Nis absorption, was found to account for their anomalous surface charge. Further, other positively charged alkali halides, LiF, NaCl and KI, were found to be free of oxygen defect states. Nevertheless, oxygen defects can be created in these alkali halides to make them negatively charged and has been demonstrated for NaCl. Such negatively charged NaCl can be readily floated with positively charged amine collector colloids thus confirming the surface charge/collector colloid adsorption theory.

Jan 1, 1996

By Yueyue Ding, Yuanhui Li, Zhengrong Li, Pengfei Yu, Kunmeng Li, Zhipeng Xiong

The stress evolution and failure characteristics of overburden were studied during multi-stope mining for a gently inclined thin orebody. Firstly, an indoor physical experiment was conducted on the excavation of a multi-stope mine with an orebody dip angle of 20°. The results show that the vertical stress concentration area gradually shifts to deep-buried rock mass with the mining from shallow to deep buried stopes, resulting in shear failure originating from high stress. On the contrary, the pressure relief zone presents an asymmetric distribution characteristic that is biased towards the upper part of the goaf, resulting in large subsidence and tensile failure of the stope #1 and #2 roofs. Secondly, the numerical simulation model under the same geological condition was established to measure the roof deformation at different stages of mining. The numerical simulation results are in good agreement with the physical test results; the roof displacement is largest in stope #2, second-largest in stope #1, and smallest in stope #3. Finally, the evolution of deviator stress concentration, displacement field and potential failure zone of overburden under different orebody dip angles were studied. As the dip angle of the orebody increase, the deep-buried stope roof changes from deviator stress release to deviator stress concentration in different stages of mining, and shear failure is most likely to be induced when the orebody dip angle is 30°. Meanwhile, the closure displacement of the stope roof decreases gradually, while the tangential displacement increases, so the anti-sliding ability of the support bodies in the stope should be improved. The potential tensile failure zone gradually shifts from the center of the goaf to the upper part, and the deep-buried stope roof evolves from tensile failure to shear failure. Results of this research expected to provide guiding significance for stope support design to control roof deformation and failure, to ensure the safety of the stope.

Mar 2, 2023