Search Documents

By Frank W. Pereira

The Montana Talc ore body was discovered in 1983 in Montana's Gravelly Range, about 40 km (25 miles) south of Ennis. Initial drilling indicated a 910-kt (1-million st) ore body of high purity talc. Preliminary analyses on ore cuttings included chemical analysis, brightness measurements, and microscopic evaluations of the structure of the talc. Results indicated it was similar to talc currently being marketed from Montana and it would probably have good commercial value. Based on the positive test results, a test pit was made and a 180-t (200-st) sample of ore was mined. A portion of the ore was ground to various particle sizes and evaluated to determine its strengths, weaknesses, and other characteristics. The deposit is located close to the Cyprus Yellowstone deposit. It was therefore believed that Montana Talc ore may possess many of the same characteristics. Testing and analyses showed the talc to have a high purity and an extremely large surface area, even for Montanatype tales. The ore was also situated in a massive deposit, indicating low cost mining. While the lab analyses were encouraging, the true evidence would be obtained from commercial tests in the marketplace. About 91 t (100 st) of ore were ground to product specifications for pitch control, paint filler, and plastics filler. Consumers were contacted and requested to evaluate the sample talc products. A major trial for the talc as a pitch control agent was arranged at a Northeast paper mill. The trial indicated the new Montana Talc product performed as well or better than the current standard in the industry. In fact, due to a minor modification in the compaction process to make the transport of the talc easier, the product had substantially less dust than the currently used product. The operating people at the paper mill requested that management purchase this talc. Trials were also run at paint plants for use as a pigment filler. And the talc was fabricated into a number of plastics compounds. The initial product tests were largely positive and provided encouragement to proceed with the project. Different grinding mills were used and their performance evaluated. Significant data were generated by the custom grinders. They indicated how the Montana Talc ore ground and the particle size distributions produced at different grinding settings. Encouraged by the positive marketing tests, a prefeasibility study was commissioned. A talc grinding plant and mine plans were designed and capital and operating costs estimated. Initial economics showed an attractive return. The operating costs were among the lowest in the industry. The positive economics, along with the excellent results by the products in the marketing tests to the paper, paint, and plastics industries, led to the recommendation to proceed with the project. Plant construction began in June of 1985. The Montana Talc Co. (MTC) analyzed the data from the commercial tests. Based on the product's outstanding performance and the uniqueness of its high purity and platy structure, a strategy was developed to position the company as a premium talc supplier.

Jan 1, 1989

By R. Riding

Degussa Corporation's peroxide-assisted leaching (PAL) process was evaluated in the batch concentrate leach circuit at Hecla Mining Company's Republic Unit. The product leached in this batch circuit is a high grade gold-silver sulfide (predominately pyrite) flotation concentrate. The primary objectives of the test program were to determine the effects of dilute hydrogen peroxide addition on leaching kinetics, sodium cyanide consumption and precious metals recovery. The results of the testing demonstrated that using dilute hydrogen peroxide produced the following benefits: - 1. Batch leach time requirements decreased by 80%. - 2. Sodium cyanide consumption in concentrate leach reduced by 55%, which translated to an overall plant reduction of 20%. - 3. In the concentrate leach process, gold recovery was increased by 1 to 2%. Because of the excellent metallurgical results achieved with the use of dilute hydrogen peroxide, as well as an economic incentive, PAL has become standard practice in the concentrate leach circuit operation. A complete description of the Republic PAL plant evaluation and performance is provided in this paper. In addition, process chemistry considerations in regard to the role of hydrogen peroxide are discussed.

Jan 1, 1992

By R. S. Datta

Regulations on sulfur emissions have caused the electric utilities to evaluate various methods of meeting them. Low-sulfur, low-volatile coals can be burned alone or blended with high-volatile? coals. This option may be a cost-effective alternative to the installation of scrubbers on coal-fired combustion systems. In some blending applications, problems may be encountered because the low sulfur content and high calorific value of the low-volatile or other clean coal allow it to economically upgrade extremely poor quality coal. While this is done to meet specification purposes, actual boiler performance may be dominated by the poorer quality coal. Thus, the reputation of the low-volatile or other clean coal suffers. As a result of laboratory and full scale testing, conducted over the last five years, a model has been developed to evaluate the relative combustion characteristics of various coals and coal blends. A database for different coals has been gathered. This paper presents the model and shows how power plants and coal mine personnel can use it to evaluate their coals from different sources. It can be used to blend two or more coals from different sources so that thee blended coal has flame stability characteristics which are similar to those of the baseline coal.

Jan 1, 1991

By Ben Benally, Joseph M. Hans

INTRODUCTION The decontamination of the former Shiprock uranium millsite and the interim stabilization of its tailings piles began in March 1974, and ended in June 1978. Personnel monitoring for whole body gamma ray exposure was conducted for selected individuals working at the mill site throughout most of this period. The millsite and exposure conditions are briefly described to develop a basis for interpretation of the exposure data. Millsite The Shiprock uranium millsite is located in the community of Shiprock, New Mexico on a bench overlooking the San Juan River (Figure 1). Both Shiprock and the millsite are located on the Navajo Indian Reservation. About 1.5 million tons of tailings were produced on the millsite during its operation from 1954 to 1963. The tailings were pulped with waste process fluids and water, and discharged to form two tailings piles. The piles (ponds, dams) were formed with earth starter dikes and the dikes were then raised using the separated sand fraction of the tailings. The slime fraction of the tailings were discharged into the diked impoundment. The mill was shut down and partially dismantled before the lease expired in 1973, and the remainder of the mill and tailings reverted back to the Navajo Tribe which was the lessor. Portions of the millsite were then occupied by the Navajo Engineering and Construction Authority (NECA), a tribal enterprise. In addition to its regular activities, NECA established an on-site training school for heavy equipment operators. The trainees principally used the south tailings pile as a practice area and spread the tailings into a 10 hectare row of raffinate ponds located along the southwest side of the millsite. Overall, the training activities inceased the effective area of the tailings piles from 20 to 35 hectares. Another 56 hectares were contaminated with wind and water eroded tailings. Exposure Conditions Persons decontaminating a millsite may be subject to radiation exposures from several sources. Only whole body gamma exposures are discussed in this report. These exposures are arbitrarily divided into three levels: high, intermediate, and low. The levels are related to areas in which the decontamination work was being done and have no connotation concerning imminent hazards. High exposures would result when persons were working with raw tailings, and intermediate exposures would occur when persons were working in the ore storage and mill yards. Low exposures would result from working in areas where surface contamination exists from wind and water erosion. [ ] The millsite and its contaminated environs were divided into major areas to facilitate the decontamination work (Figure 2). Areas A, B, and C are defined as perimeter areas containing surface contamination. Work in these areas was expected to result in low exposures. Areas D, E, and F are the

Jan 1, 1981

By Cary Hirner, Sarah Lothman, Chris Mueller, Savita Schlesinger, Mike Hanna, Ian Fitz-James

Loudoun Water is currently implementing a quarry to reservoir conversion that will improve water supply reliability in periods of drought and flexibility in water supply operations when turbidity in its Potomac River supplies are high. The Milestone Reservoir Project consists of an inter-tie to the existing Potomac River Pipeline; new pipeline and tunnel; and a pumped intake and outlet works. Planned construction involves significant risks due to underground conditions which includes hard, igneous rock and high groundwater at the creek crossing. In addition, the site is constrained by Goose Creek, an adjacent residence, active mining in a quarry next to the new reservoir, public use of adjacent park space, and the Washington and Old Dominion Trail. Working with these constraints will require close coordination with active mining operations and public and private property owners. Safety of personnel involved with construction also represents a concern with quarry high walls over 30 meters in height near the planned construction. In consideration of key projects risks, Loudoun Water determined that an innovative CMAR delivery approach provided the best opportunity to achieve its goals in quality, innovation, front-end cost and schedule certainty, and operational flexibility and reliability. What matters most to Loudoun Water is the value in having a builder participate in the design process where key decisions can be made based on consideration of risks, cost, schedule, quality, and operability and maintainability of the system. While a progressive design-build delivery model may have produced similar outcomes, Loudoun Water had already invested in substantial development of the design for the work, and ultimately, CMAR provided Loudoun Water the opportunity to retain the partnership with the design team while gaining valuable input from a contractor. Among the challenges with CMAR in the Commonwealth of Virginia is a substantial limitation on self-performance corresponding to 10 percent of the construction value of the work. A significant industry outreach program was initiated by Loudoun Water to encourage participation with incentives in contract terms that allowed for the CMAR Contractor to make a reasonable profit. This paper reviews the CMAR procurement process and discusses contract incentives that were adopted to promote the work within the constraints of contract law in Virginia.

Jun 13, 2021

By Robert L. Llewellyn

The Wharton No. 2 Mine of Eastern Gas and Fuel Associates is located about 60 miles south of Charleston, West Virginia in Boone County. Daily production is 6,000 T.P.D. on a two-shift basis. The Hernshaw Seam is mined by conventional equipment with one continuous miner in areas where conditions are suitable. The plant is on Cow Creek .Branch of Pond Fork, which in turn flows into the Little Coal River at Madison, West Virginia. When the mine was opened in 1948, plans were developed to build a dual Baum jig plant complete with mechanical and thermal drying, and because full production would not be reached for several years, it was decided to install only one Baum jig setup although the complete structure was erected. This phase of the plant was placed into operation early in 1949, The rated capacity was about 300 T.P.H. of 5" x 0 raw feed to the jig. Being a drift mine, the 10-ton mine cars are dumped at the Headhouse, crushed to 8" in a double roll crusher, conveyed 780 feet downhill to the picking .house where the +5" slate is removed by pickers. All coal is crushed to 5" and 5" x 0 is conveyed 150 feet to the cleaning plant. Further describing the plant growth, the second jig setup was installed in 1954 to clean the increased production. During this operating period, exhaustive tests had ,been run on the plant bleed which was an overflow from the large sludge tank located inside the plant, When the second jig addition was undertaken, 5-14' diameter and 12-8" diameter cyclones with a 9-disc filter were installed for the solids recovery and water clarification system, However, the circuit was not closed and a bleed of part of the overflows from the 8" diameter cyclones was still necessary, To comply with the State Water Commission regulations on stream pollution abatement, four pumps in series were installed to discharge the waste water behind the refuse pile.

Jan 1, 1959

By Don Rose

Steel-fiber-reinforced-shotcrete (SFRS) methods of testing and the wording of specifications vary from country to country. In the USA ASTM C1018 is widely used. The Canadians have taken a close look at C1018 and point out that exact determination of the first crack is very subjective, and they propose a method of design that eliminates this variable. The Europeans (EFNARC) have taken the principles of testing a step further than ASTM C1018, and have added a new step in measuring the effectiveness of SFRS. EFNARC uses an "energy absorption" of a plate loaded in its center, in addition to the principles of C1018. The principles of SFRS design are also used in Japan, Norway and elsewhere.

Jan 1, 1999

THE FUTUREGEN CLEAN Coal project will be the recipient of $1 billion worth of federal stimulus money by way of the U.S. Department of Energy (DOE), which announced the commitment to the project. The money is expected to kick off years of further work that could finally see the project completed. One of the companies involved, Ameren Corp., said the $1.2 billion project ? which will include some private funding ? still has a number of hurdles to clear.

Jan 1, 2010

By S. C. Sun

A process was developed to recover coal, clays and pyrite from coal wastes. The process consists of fine grinding followed by coal flotation and pyrite flotation leaving the clays in the flotation pulp. A bituminous coal refuse, containing l0% S-30% C*, was treated by this method to yield a coal product containing 4% sulfur, 10% ash; a pyrite product containing 45% sulfur (84% FeS2), 1% carbonaceous material and a clay product containing 2% sulfur (3.5% FeS2). The coal yield was about 89%. The pyrite yield was about 77%. The process steps may be entirely flotation, or gravity separation (hydrocyclone) may be used to increase the pyrite: coal ratio in the flotation feed. Cost estimation shows a profit of $2.28 per ton of low pyrite grade refuse (Labor, maintenance, overhead and plant depreciation were not included). The development of this process consisted of three parts: 1) exploratory tests, 2) optimization tests and 3) confirmatory tests.

Jan 1, 1968

By B. A. Ashley

In 2007, Rosebud Mining Company (RMC) opted to extend the reserve base of Tracy Lynne Mine by developing through a sandstone channel. The extension provided access to approximately 6 million additional recoverable tons (approximately 8 years of mining) which originally had been deemed inaccessible. An evaluation of the mine?s existing ventilation system, which was designed to meet the needs of the original limited reserve, concluded that two ventilation shafts would likely be required to adequately ventilate the projected workings in the expanded reserve. To assist in the evaluation, a ventilation model of the mine was developed using Ohio Automation?s ?ICAMPS MineVent? software based on field data from Tracy Lynne Mine, prior ventilation survey experience at similar RMC mines, and relevant published sources. Model results suggested that the most economical shafts would be an 8-ft diameter return and a 4-ft diameter intake. Unfortunately, issues related to property leasing and shaft site permitting caused construction delays. Therefore, the model was also used and proved to be effective in prioritizing interim ventilation upgrades which could be implemented in order to maintain coal production. Model results indicated that the best interim upgrades included rehabilitating restricted entries and damaged stoppings and replacing the main fan with a higher pressure fan. From late 2010 to mid-2012, all interim upgrades and shafts were implemented. Current models and mine experience indicate that ventilation will not be the limiting factor for mining the additional reserve.

Feb 23, 2014

By V. P. Keran

Design of the Bajo de la Alumbrera Project started in June 1995 and concentrate production commenced early in the Third Quarter of 1997. The project is situated in North-Western Argentina and is being developed by Minera Alumbrera Limited which is owned by MIM Holdings Limited of Australia (50%), North Limited of Australia (25%) and Rio Algom Limited of Canada (25%). This paper outlines the key features that were incorporated in the design from both process and plant layout perspectives. It explains the background of flowsheet and equipment selection for the plant. A feature of the flowsheet is that it incorporates gravity gold circuits in both primary and regrind circuits for recovery of gold to dore as well as in the copper concentrate product.

Jan 1, 1998

By S. Chatterjee, S. Bandopadhyay

A spatial modeling technique based on the Bayesian neural network (BNN) is proposed. Incorporation of the Bayesian method for posterior probability of the output parameter helps calculate the uncertainty associated with the estimate. Parameters of the BNN model were selected using a grid search algorithm. The expected value and the variance of block support were calculated by Markov chain Monte Carlo sampling of the posterior distribution at discretized points within the block. The BNN model was validated by applying it to the Walker Lake data set and comparing the results with ordinary kriging results. The comparison revealed that the proposed BNN method performs marginally better than ordinary kriging. The variance map is less smooth than with ordinary kriging, and the proportional effect is less in the BNN-based model than in the ordinary kriging model. The developed BNN model was applied to the Coho block of a placer gold deposit in Nome, AK. Results reveal that the BNN model is globally biased for the Coho block and underestimates the sample mean. The grade volume curve was developed by calculating the block mean and block variance after discretizing the block into a number of points and applying the BNN model to each discretized point.

Jan 1, 2011

By V. A. Shea-Albin

Sandstone escarpments surrounding western coal-bearing plateaus serve as critical habitat for animal species. Effects of mining subsidence on escarpment stability are not well documented; therefore, regulatory agencies may limit extraction of coal reserves underlying escarpments. Because millions of tons of this coal exist on Federal Lands, associated public revenues from Federal royalties, and valuable coal reserves, risk being lost. The U. S. Bureau of Mines is using numerical modeling techniques to analyze effects of subsidence on escarpment stability. Finite element models that incorporate bedding plane slip, gob formation, and movement along joints simulate escarpment subsidence observed in the field.

Jan 1, 1994

By C. Sun

The Leeville underground mine has been in operation since 2006 and currently produces 2,903 t (3,200 st) of ore per day, with an average gold grade of 0.4 opt. The mine’s horizontal extent is large, 762 by 152 m (2,500 by 500 ft), while its vertical extent is 6 to 61 m (20 to 200 ft). A high density of joints occurs within the host rock. Based on rock mass rating and field observation, the ground conditions at Leeville can be characterized as poor to very poor. As such, heavy ground support is required for its mining operation. Ore zones with a height in excess of 10 m (35 ft) are considered for longhole stoping. A typical stope measures 6 m (20 ft) wide, 30 to 55 m (100 to 180 ft) long, depending on the ground conditions, and 10 to 30 m (35 to 100 ft) high, depending the thickness of the ore body, yielding 9,100 to 18,000 t (10,000 to 20,000 st) when completed. Narrow ore zones, less than 10 m (35 ft), are mined using cut and fill. Drifts at the Leeville Mine are 4.6 m (15 ft) wide by 4.6 m (15 ft) high. Because of poor ground conditions at this mine, the establishment of a ground control monitoring system is key to operating both safely and successfully. This monitoring system is composed of comprehensive instrument design and installation. Instruments include multi-point borehole extensometers (MPBX) and “stretch measurement to assess reinforcement tension” (SMART) cables. The monitoring system covers the mining zones and infrastructure openings. After about two years’ application and measurement, useful data has been collected and continues to be collected; this information will be used to design future stopes and infrastructure. The system makes engineering and operation teams able to do their job with more confidence and efficiency.

Jan 1, 2009

By D. I. Hoyer

A preliminary model has been developed for autogenous pebble milling using information obtained from studies on ball milling and SAG milling. The model treats the breakage as the weighted sum of first-order breakage of smaller particles by tumbling pebbles, non-first order breakage of larger particles which are too large to be nipped properly by pebbles, autogenouS fracture and chipping of larger lumps to form pebbles, and autogenous fracture and abrasion of pebbles. The model includes the effects of residence time distribution, classification through the exit grate, and a mass transfer relation which describes the accumulation of fine material in the mill. Example simulations are given, based on breakage parameters determined from batch grinding tests in laboratory mills. fracture breakage and abrasion. In the development of these preliminary mass balance equations it will be assumed that breakage by fracture is first-order, but this assumption will be modified later in the paper. It will also be assumed that the residence time distribution of a long autogenous mill can be described by an equivalent series of m fully-mixed mills, with a classification action imposed on the mill contents by the discharge grate. Size distributions are expressed as a v2 geometric series, numbered 1 for the top size down to n for the fines, or "sink" interval. If the holdup in the mill is W then the rate of breakage of material in size interval i is given by SiwiW, where wi is the fraction of material in size interval i, and Si is -the overall specific breakage rate of size i material (fraction per unit time).

Jan 1, 1985

By J. A. Marts, R. C. Gilmore, Jr. Bogin, S. Saki, J. F. Brune, J. W. Grubb

"Researchers at the Colorado School of Mines have studied the influence of headgate side ventilation controls near the longwall start-up room on the formation of explosive gas zones (EGZs) in underground coal longwall bleeder ventilated gobs. In a project funded by the National Institute for Occupational Safety and Health (NIOSH) researchers developed a Computational Fluid Dynamics (CFD) model to study the formation of methane-air mixtures in the gob, start-up room, and bleeder entries. The relative change in size and location of EGZs are examined in response to ventilation controls in the headgate side bleeder entries near the start-up room. Modeling suggests that adjustments to the ventilation controls can be made to minimize the size of the EGZ. However the EGZ may form in or around active working areas regardless of the ventilation control settings. Research found regulators on the crosscuts into start-up room and first entry inby can force air into to crosscuts outby the start-up room causing more air to flow through the gob. INTRODUCTION Underground longwall mine ventilation systems may operate with either a bleeder ventilated gob or a progressively sealed gob. Bleeder ventilated gobs must meet the standards for safe operation of the bleeder system by examining bleeder system effectiveness. As defined in the United States Mine Safety and Health Administration (MSHA) Program Policy Letter (PPL) No. P13-V-12 (MSHA 2013), the pillared area or gob is “any area where a reduction in pillar size has occurred during retreat mining” and includes the “caved and broken material, the interstices within the caved material, and the open spaces surrounding the caved material.” The PPL further states that the intended purpose of ventilating the gob is “to protect active workings from the hazards of methane accumulations …” The requirements for operating a bleeder system as stated in The United States Code of Federal Regulations (CFR 2013) Title 30 §75.334(b) is to pass ventilation air though the gob “and to continuously dilute and move methane-air mixtures [from the gob] away from active workings and into a return air course …” where the concentration cannot exceed 2 percent methane (CFR 30 § 75.323). Further clarification of the bleeder system as described in the PPL states the following: “A bleeder system includes the area from which pillars are wholly or partially recovered, bleeder entries, bleeder connectors, and all associated ventilation control devices that control the air movement through the area. Bleeder entries are air courses designed and maintained as part of the bleeder system.”"

Jan 1, 2015

By Khosrow Badiozamani

Operating mines in Wyoming and Montana, which are generally characterized by shallow overburden and thick coal seams, are faced with reclamation problems which are unique to this area. Unlike the eastern or midwestern mines, removal of thick coal seams and lack of sufficient overburden creates overburden deficiencies that require careful evaluation prior to mining to insure compliance with regulatory requirements. Computer models and computer graphics can assist in such evaluation where appropriate alternatives can be selected which satisfies both the regulatory requirements and minimizes cost. This paper presents one such model used in evaluation of backfill requirements for restoration of surface and ground water regimes, restoration of mined-out areas to the approximate original contour, and the blending of the mined-out areas to the surrounding topography.

Jan 1, 1981

By Jean-Luc Cornet

Downhill, or regenerative conveyors have always been a challenge to the design engineer due to their natural instability under load. The last decade has seen the appearance of high tonnage, high negative lift conveyors with several hundred meters of drop. These conveyors have made necessary the development of new braking systems and intelligent drive controls to address their starting and stopping requirements under various load conditions. This paper describes the critical design criteria of large regenerative conveyors and some of the advances in mechanical braking systems and drive control technology developed by Conveyor Dynamics, Inc. (CDI) to address their specific requirements.

Jan 1, 1993

By I. Demers, A. Blier, M. Mbonimpa, M. Benzaazoua, B. Bussière

The Doyon Mine in Quebec, Canada, evaluates the possibility of desulfurizing its tailings to produce material to be used as cover for the acid-generating tailings disposal site. Laboratory tests showed that a single-layer cover made of desulfurized tailings placed over reactive tailings can prevent the generation of acid mine drainage. Modeling with the software Vadose/W was used to optimize the design parameters, namely, cover thickness, water table position and residual sulfide content of desulfurized tailings following laboratory work. It was found that the optimal configuration includes a 1-m (3.3-ft) desulfurized tailings cover containing 0.8% S, with the water table kept at the interface between the reactive tailings and the cover. To maintain the cover performance to reduce oxygen flux toward acid-generating tailings even in the event of a long dry period, a sand layer is suggested to protect the cover from excessive evaporation. It is possible to reach the environmental objective for oxygen flux chosen for the Doyon Mine (10 mol/ m2/year) with the protective sand layer, even in extremely dry conditions.

Jan 1, 2009

By M. Z. Emad, M. U. Khan

"Coal mines opting for longwall mining or its variations rely on the main and tail gates for production. Stability of these entries or crosscuts is crucial in coal mining operations. Roof or strata failure can be fatal, may lead to property loss and delay in production. Failure of the gates depends upon many factors including the mining method, panel dimensions, pillar width, mine depth, caving rate, dimensions of gates and roof strength properties. In Pakistan coal is mined through a variation of longwall mining method with almost no mechanization while using timber as a primary support. Timber support as chock is very useful in coal mines especially in overhanging face. Similarly gate entries and coal faces are supported by chock supports throughout their length. In this paper the stability of the longwall gate is assessed for a typical coal mine in Pakistan by using finite element code. Numerical modelling considerations for gate entries are discussed. A model parametric study is performed for key factors. The results showed that the existing mining practice is not suitable and there is a need to review the mining approach. INTRODUCTION Main and tail gate entries leading to longwall mining panel play a crucial role in production cycle. Failure of any of these may lead to loss of life, property and production delays. The stability of gate entries depends primarily on the nature of loading and stresses incurred. It is relatively easier to assess the ground response to production for common longwall mining panel. In thin-seam coal mines the gate entries are generally supported throughout their length by timber made chock supports. The tailgates receive huge deformations and stresses during the mining and backfilling cycle. The chock supports are required to take care of rock falls leading to blockage of entries causing production delays and loss of capital. A number of supports are available for supporting the gate entries (Hoek and Brown 1980; Brady and Brown 1985). The support system can be selected based on load-deformation characteristics including the yielding behavior, pre- and post-yielding behavior (Barczak, 2003). The principal of support selection is that the support characteristics must match the ground response in order to maintain the gate entries (Mucho, et al., 1999). It has been observed that thin-seam mining (<1 m) is very challenging and it is necessary to develop an understanding of ground mechanics before the selection of an efficient support system Dolinar (2003). The chock supports have been tested for load-deformation characteristics in the laboratory (Barczak 2003). But the ground and support interaction, response and loads must be assessed for individual site. This can be accomplished by in-situ testing and observations at few locations. The generated data is generally insufficient for complete understanding. Numerical models can combine the data generated in the laboratory and on-site to fulfill the requirements."

Jan 1, 2017