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By Albert L. St. Peter

The "Old Reliable" four million pound blast in March of 1972 marked the opening, as far as is known, of serious efforts to commercialize the In Situ concept. That was a coyote shot, and it was followed by three blasts at McAlester Fuel's "Zonia" operation which were surface hole shots. As the only individual who had a principal part in all four shots, it seems to be appropriate to present experiences in the developments and evolutions of the in Situ method of ore extraction. Some of the problems will be described, along with proposals for management of such projects in the future.

Jan 1, 1976

By M. C. Mound, L. Fradette, C. Colbert

Metallurgical Accounting in the mineral processing industry transforms accumulated process data, including flow rates and assays, into a coherent information format. This is used to rapidly provide production reporting and key performance indications. A fully comprehensive and coherency of available data must be a component of any system expected to accomplish reconciliation in the mass balancing process. Quality issues are thus improved with such desired methods via a mass-balancing engine utilizing the results of measurements acquired by various on-line sensors, analyzers, and sophisticated laboratory equipment. Metallurgical Accounting, when accomplished through such an engine, provides high value information in a simple, straightforward, and simplified manner. Exceptional utility is then transparently available to authorized personnel for access to metallurgical accounting reports, production reports, mass balance results, performance indicators, and so on. This paper discusses how such information can be used to "drilldown" into each result set by consulting the data hierarchy to evaluate and validate calculations and input data used to produce the specific results being queried. The power of such a system resides in the full and true integration of all production and laboratory data. What is integrated are the data thus acquired via a single user interface, a single database, a single configuration tool, etc. From this comes the derivation of contextual information and its maintenance. It is possible to reduce metallurgical accounting and production reporting from possibly hours or even days to a matter of minutes. The result is maximization of information reliability and availability from masses of otherwise discrete and difficult to access key data.

Jan 1, 2003

By H. EI-shall

Bench top centrifuge is used to study the consolidation behavior of phosphatic clays. A mathematical model (based on first order kinetics) is developed to describe the relationship between the void ratio (at any time) and the effective stress. Permeability of the sediment as a function of the void ratio is also described. The obtained data are compared with that obtained by other consolidation testing methods. Centrifuge results indicate that consolidation data may be developed in a short period of time (hours) as compared to days or weeks when other techniques are used.

Jan 1, 1995

By Wayne D. Gould

The Cities Service Company's Pinto Valley mine and concentrator lie about 6 miles west of the town of Miami, Arizona at an elevation of approximately 4,000 feet above sea level. The concentrator started its first ballmill in July 74 and all six were available by November. Every effort was made to reduce capital costs, consequently, each unit process was studied critically to eliminate excess capital costs without loss of efficiency. Equipment selection was made on the basis of proven dependability and operating costs rather than on low bids. The result is a very workable plant with some important innovations. The concentrator is nominally 40,000 tons per day. The flowsheet is typical with 3 stage crushing, single stage closed circuit grinding, flotation, regrinding of rougher concentrate and cleaning of the rougher concentrate. The major equipment list is: 1 60 x 89 Traylor Primary Crusher 1 84" x 20' Stevens-Adamson Apron Feeder 3 7' x 16' Double Deck Tyler Screen 3 7' Nordberg Standard Crushers 6 8' x 20' Tyler Screens

Jan 1, 1975

By Fitzhugh T. Lee

Results from the first part of a two-part investigation of the stability of highwalls in open-pit coal mines in the Paleocene Fort Union Formation of the western Powder River Basin of Wyoming and Montana indicate that these highwalls are subject to time-dependent deformation. Field investigations and laboratory physical properties tests of coal and overburden rocks suggest that several factors influence highwall stability. Some of these factors are rebound of overconsolidated rocks, desiccation, water, orientation and spacing of fractures, and strength and deformation properties. Factors of safety for a typical highwall in the study area (calculated by the finite element method) may be less than 1.0 when open fractures are present and the highwall has degraded. Although it is concluded that most open-pit highwalls in the Fort Union Formation within the study area have adequate short-term stability, these highwalls do deteriorate and become progressively less stable. Because of this, postmining failures are common and stability conditions could become critical if mining were delayed and then resumed after a period of several months. The second part of the investigation will utilize field measurements of rock-mass properties and instrumentation of actively mined highwalls to obtain data for comparison with the results of the initial investigation. Because the height of highwalls will increase as the more shallow coal is exhausted, these data will also be used to predict the behavior of slopes higher than those presently found in the western Powder River Basin.

Jan 1, 1977

By D. W. Mitchell

Planning today for what hopefully will never happen is one of the surest ways to decrease the chance of it happening. As Napoleon proved and Ian Mitroff wrote, "The heat and stress of battle is the worst time to make decisions of strategic importance." Mitroff also wrote, "The value of a plan is not that it will ever perfectly match reality, but going through the process of planning speeds the process of recovery. It allows the organization to emotionally work through the worst before it actually happens." This paper concentrates on things miners must consider; on the need for plans to be like a belt conveyor strong enough to carry the load, flexible enough to stretch a little; on the criticality of throwing away fax machines and telephones, and having certain officials at the scene rather than back in head-quarters; on the training of fire brigades and mine-rescue teams; on having company-controlled chromatographs; on having people who can look at trends rather than numbers. Some of the things in this paper might anger some readers; for that, I can only ask them to consider first the problem not their position.

Jan 1, 1993

By S. D. Bearden

China was the world’s leading producer of barite during 1995 with 35%. The United States followed with14%. India produced 9%. Other producers included Morocco, Turkey, Mexico and Germany. Domestic production of barite during 1995 was estimated to be 600 kt (660,000 st). Nevada produced 85% of the total. Georgia was the second leading barite-producing state. The United States is the world’s largest consumer of barite. During 1995, it used 1.6 Mt (1.8 million st). US reliance on imported barite during 1995 was about 63%of total consumption, according to the US Geological Survey.

Jan 1, 1996

By Donald R. Williamson

The Cyprus Pima Mining Company's open pit operation was started in 1957 with the normal assumption that the ore reserve estimate was accurate within an acceptable range of values. At that tine reserves were law - volume (+10 million tons) and high grade (+1.5% Cu). Several periods of growth have brought the operation to its present production level of 55,000 tons per day of ore and +125,000 tons of waste. Over the years, a number of attempts to refine and polish the ore reserve figures have been made using a variety of established standard procedures. None of these attempts have produced results which are totally satisfactory, particularly when comparisons are made between ore reserve estimates and short to medium range production figures. Other refinements were tried using adaptations of established methods combined with computer modeling techniques. The resulting mine-model ore blocks were an improvement but they still tended to show too match tonnage of mill feed, often at too low a grade. One attempt at Kriging had only limited success. Statistical studies of operations data revealed relationships which could be used to subdivide ore blocks in much the same way as they are actually mined. Comparisons thus far between these newly developed ore blocks and production data show that the new method of evaluation yields excellent results. A new, better procedure for estimation of ore reserves apparently has been developed for the Cyprus Pima deposits. The specific procedures seem likely to have direct application to other, similar operations. The methods used to develop the procedures could be of value to still other operations.

Jan 1, 1976

By David Dvorkin, Thomas C. Anderson

INTRODUCTION A major function of the Mine Safety and Health Administration (MSHA), Denver Safety and Health Technology Center (DSHTC), Ventilation Branch, is to provide engineering analyses of underground mine¬ ventilation systems for coal, metal, and nonmetal in¬spection departments in accordance with field surveys and data analyses. Health and safety problems such as the control of diesel contaminants, dust, methane, radon, and radon daughters all are dependent upon ventilation. It is necessary for the ventilation engineers at DSHTC to have a complete understanding of the various and highly complex ventilation systems used in the nation's mines. Only through the proper assembly and analysis of data can the engineer determine the causes of prob¬lems and make suitable recommendations. Furthermore, the engineer must have the ability to predict the results of any such recommendations. In the study of the ventilation system at any indi¬vidual mine, it is common practice to collect data on airflow quantities and pressures at key points throughout the mine. However, these data give only a single point¬-in-time view of the system. As the mine develops and progresses, the system undergoes numerous changes; as the mine becomes more extensive, the ventilation re¬quirements increase, and the costs rise. For proper utilization of the available resources, it is necessary for the engineer to have a sound engineering basis for deci¬sions on how best to ventilate the mine. To evaluate the system as a whole, particularly re¬garding possible system changes, it has become necessary to rely on computers to perform the calculations in¬volved in analyzing the network. This chapter sum¬marizes the implementation of such computer capabili¬ties at DSHTC, as well as the services that are available from DSHTC. ANALOG SIMULATIONS AND ANALYSES OF VENTILATION NETWORKS As early as 1954, the US Bureau of Mines (USBM) in Pittsburgh, PA, was using an analog computer as an aid in analyzing ventilation systems. The Mcllroy Fluid Network Analyzer used filament-tube resistance elements and an electrical power supply to simulate mine-ventila¬tion systems electrically. This system is shown in Fig. 1. Analog simulation has proven to be a practical tool, providing fast analyses of complicated problems after the initial setup has been completed. Advancements in electronic technology over the past 24 years have made possible the construction of an analog computer that has streamlined several operating features of the previous machines. The DSHTC Ventilation Branch now has an improved electronic analog computer to assist in the analyses of ventilation systems. General Features As shown in Fig. 2, the analog computer used at the DSHTC Ventilation Branch has three "element" cabi¬ nets, a console, and a printer. The cabinets contain the fan elements and the airway-resistance elements that are used to "program" an analysis problem; each element is independent of the others. The console contains the "patchboard" and the controls necessary to operate the analog computer. The patchboard connects the inde¬pendent elements into the circuit appropriate for simu¬lating the ventilation system. The total system is controlled from a panel on the console, while the value corresponding to each element is set on the individual controls located on the face of each element. The control panel has three visual output displays that give the quantity of flow, the pressure of the output junction with respect to a datum, and the differential pressure across each element. The control panel also allows manual selection of the element to be monitored, or automatic scanning and printing of values for the entire system. Capabilities The analog computer can simulate an existing mine¬-ventilation network. This is accomplished by collecting field data at the mine to give a complete pressure-¬quantity network. Resistance values for each airway branch may be determined from the quantity of flow in the branch and from the pressure differential between the end-point junctions of the branch. The basic rela¬tonship to determine the resistance is expressed as: H=R •Q2 where H is the pressure differential, R is the resistance, and Q is the quantity of air in the flow. After the resistance values are known for all of the airways in the circuit, the elements on the analog com¬puter can be set to the corresponding values. The elements are designed to reflect the basic relationships, with electrical potentials corresponding to pressures and

Jan 1, 1982

By D. Kwak, S. Han, J. Kim, Y. Lee

"INTRODUCTION In carbonate rocks, it is difficult to characterize due to the high degree of heterogeneity in pore geometry. Carbonate rocks have various types of pore systems such as fractures and vugs, and this heterogeneity should be considered for more realistic prediction of oil production in carbonate reservoirs. This study carried out water flooding experiments using five carbonate rock samples in order to observe the change of physical properties. Firstly, qualitative and quantitative analyses were conducted for each carbonate samples by use of XRD and XRF to evaluate the mineral content. All samples are mainly composed of CaCO3 and after that, the ICP experiments were carried out for the water passing through the carbonate. As a result, it was possible to measure the quantity of CaCO3, MgO, Fe2O3 component in water and due to this effect, the permeability of carbonate was altered especially in the front part of the core. Finally, after the carbonate was saturated by 30 API crude oil, water injection to enhance the oil recovery was repeated and it was confirmed that the oil-producing characteristics are different depending on the dissolution characteristics of carbonate rock samples. CORE SAMPLE ANALYSIS Porosity and Permeability Experiment Porosity and permeability were measured. The procedures are as follows (Figure 1). 1. Measure the diameter and length of the dry core using Vernier caliper. 2. Put the core in the core holder, run vacuum pump until the inlet and outlet pressure gauge equal. 3. Saturate the core using ISCO pump to inject water at 650 psi 4. Measure the amount of water and calculate the porosity 5. Set up the outlet pressure at 500 psi. 6. The flow rate measure when the equilibrium 7. Calculate the permeability through Darcy’s Law. 8. Cutting of core upstream and downstream about 13cm, and measure the each of permeability."

Jan 1, 2016

By Joseph Padgett

Of all the fossil fuels produced in the U. S., coal is by far the most abundant. U. S. reserves amount to an estimated 1.5 trillion tons, 2,500 times the 600 million tons produced in 1970. Although it would not be possible to recover all of this coal economically with current mining technology, a significant portion would be available given the proper circumstances. With existing technology, approximately one-eighth of these reserves is accessible, an amount which would last for several hundred years at the 1970 level of production. On the face of it, this substantial reserve should go a long way in meeting the Nation's energy needs. But coal offers special problems. As additional coal is mined and then burned, there are increased costs to the Nation's land, water, skies, and health. Hence, coal poses a dilemma because of its dual status as one of our most abundant domestic fuels and as one of our major sources of environmental degradation. Against the benefits that would be chalked up in the areas of national security, balance of trade, and economic well-being from the increased use of coal, we must enter on the debit side of the ledger the increased environmental cost. This paper reviews the use of U.S. fossil fuel, the drawbacks of coal as an energy source, the means being developed to overcome these drawbacks, and the background behind the present sulfur emission regulations relative to coal combustion. It also discusses in detail the Federal Environmental Protection Agency's (EPA's) current policies to ensure the continued use of coal as a major source of energy for fossil-fuel fired power plants.

Jan 1, 1973

By Solomon J. Salat

During the major expansion of the Inspiration smelter, which took place in 1973, the bulk material handling system underwent a matching expansion in order to move the required materials. Inspiration is the first smelter worldwide to employ electric smelting in conjunction with the use of Hoboken converters (1), (2). The installation includes a 51 -MVA electric furnace, five 4.25m (14-foot) diameter Hoboken converters, rotary dryer, bedding plant, acid plant, heat recovery steam plant, and gas and dust handling system. See Figure 1, Plot Plan. As of today, the 51-MVA electric furnace is the world's largest in the smelting of copper. Engineering design for the installation was per- formed by Treadwell Corporation of New York. The task of designing the conveyor system was complex because the system had to be installed while the smelter was operating and with minimum plant shutdowns, and it had to serve both the existing and the new smelter. Existing conveyors were redesigned where necessary and incorporated into the new conveyor system. See Figure 2, Flow Sheet. The system encompasses the handling of such diverse materials as wet and dry copper concentrates, cement copper, silica flux, cold dope, and concentrate and flue dust.

Jan 1, 1979

By R. Woods, J. D. Wright

INTRODUCTION The Endako deposit was first explored in 1926, but development waited until the early nineteen sixties. It first came under the control of Placer Development in 1963, and early in 1964 a decision to bring it into production was reached. The deposit is located near the geographic center of British Columbia, and is served by an east-west communication system including a paved highway, mainline railway and good telephone, teletype, and computer facilities. The plant area is shown in Figure 1. The operation is known as the Endako Mines Division of Canex Placer Limited of Vancouver. First production was achieved in June, 1965, at a nominal rate of 10,000 tons per day, but it soon was closer to 15,000 tons per day. In 1967, two new grinding and flotation sections brought capacity to the present rate of approximately 27,000 tons per day. With mill heads of around 0.15 percent MoS2, production is about 14,000,000 pounds of molybdenum per year. A flowsheet of the operation is given in Figure 2. A legend for this flowsheet is given in Table 1. Published ore reserves are estimated at 214,500,000 tons at an average grade of 0.143 percent MoS2. PRIMARY CRUSHING The 85 or 100-ton haulage trucks dump over a grizzly into a 42 inch x 65 inch C.A.C. (Canadian Allis Chalmers) gyratory crusher.

Jan 1, 1976

By U. Cetin

The Nevada Test Site is located approximately 65 miles northwest of Las Vegas, NY. The site was primarily used by the Department of Energy for the field testing of nuclear weapons and contaminated by several million cubic feet of low-level radioactive wastes, heavy metals, volatile and non-volatile organics, and explosive materials. Leaching and transportation of these contaminants are creating severe environmental problems. The purpose of this study is to examine pozzolan, a natural alumina-silicate mineral, as a possible replacement of the existing impermeable barriers (clays). In the first phase of this study, radionuclide sorption characteristics of pozzolan were investigated. This paper will present the results of the sorption tests for the target radionuclides.

Jan 1, 1998

By R. Asamoah, P. Forson, W. Skinner, M. Zanin

Despite the seeming benefits decoupling pyrite and arsenopyrite minerals present in practice, little success has been achieved. The present study presents possible process routes for attaining selective flotation broadly capitalizing on differential oxidation between these minerals, and the use of a chelating collectors. The best performance was achieved with dithionocarbamate application following copper activation, yielding 81.4% arsenopyrite and 37% pyrite recovery. Preaeration followed by staged addition of xanthate produced 76% arsenopyrite and 31% pyrite recovery while reverse flotation of pyrite after H2O2 addition gave rise to rejection of 66% pyrite accompanied with 24% arsenopyrite.

Mar 2, 2022

By William Harrison, Robert H. Trent

GENERAL DESCRIPTION History The most striking feature of mining in the United States has been the infrequent use of longwall systems. This system, which accounts for the majority of coal production in Europe, Japan, and other countries, is only recently growing out of its infancy in the mining of normal coal seams and is still untried in the mining of thick coal seams in the US. Its use in the mining of metal and nonmetal ore bodies has been virtually ig¬nored, except for isolated instances in trona, copper, and uranium. Longwall mining is believed to have originated in Shropshire, England, towards the end of the 17th cen¬tury (Laird, 1973). Although the method used would be considered primitive by today's standards, many of the basic concepts have remained unchanged. Longwall mining of coal in the US was first introduced before the turn of the century, but it never gained acceptance as it did in Europe. Historically, longwalling was a cyclic method where a single cut of coal was removed from the face on the producing shift each day, and the work of building stone packs in the gob and manually moving roof support was completed on the off shifts. Due to the amount of dead work, productivity was extremely low. In Europe, however, longwall methods were required despite the high costs involved, because only by this method could coal under heavy depth be mined with any reasonable degree of recovery. Reserves of coal lying under shallow cover, and therefore minable by room¬and-pillar methods, were long ago inadequate to supply most of Europe's coal requirements. In the US coal min¬ing has historically proceeded laterally with the new mines in virgin areas to replace old mines; in Great Britain, Germany, Japan, and many other countries, mining must proceed downward to greater depths. The depth of cover for most coal operations in the US is shallow, i.e., 61 to 305 m (200 to 1000 ft). This, combined with large reserves, has made room-and-pillar methods almost universally applicable. However, longwall systems were tried around the turn of the century. Whenever used, it was frequently noted that the opera¬tion was under the direction of men with foreign ex¬perience and was tried under ideal conditions. Some of the mines that were using longwall or had tried longwall prior to 1910 were the Radiant mine, CO; Vinton Coal Co., PA; Cambria Steel Co., Johnstown, PA; Grundy County and Spring Valley, IL; and unnamed mines in Washington, West Virginia, Kentucky, Iowa, and Kansas. As late as 1961, there was one circular longwall in operation at Centerville, IA. The first modern-day op¬eration to take advantage of European technology and longwall methods was Kaiser Steel Corp. at its Sunnyside mine near Price, UT. Due to deep cover and extremely poor roof conditions, combined with a need for in¬creased production, Kaiser management decided a new method was required and turned to longwall in 1961. The first longwall consisted of an Anderson Mavor shearer loader, British Jeffrey-Diamond conveying equip¬ment, and Dowty roof supports with a capacity made up of two and three 27-t (30-st) capacity props. After nor¬mal start-up problems, this unit averaged over 454 t (500 st) per shift (White and Palacios, 1976). During and after World War II, technology in hy¬draulics and controls had advanced to the point that self-advancing supports and hydraulic props were being developed. In 1960 only I % of West German produc¬tion was from mechanized longwall faces. This in¬creased to 37% in 1970 and 63% in 1973 (Kohlgruber, 1974). In 1976 there were 246 coal mines operating in the United Kingdom. Although this is only 50% of those operating ten years ago, the production has increased 42%, mainly through improvements in longwall equipment and methods (Hunter, 1976). In France and other European countries, the devel¬opment of longwall mechanization has been similar in seams up to 2.44 m (8 ft) thick. In seams that exceed 9.14 m (30 ft), a variety of longwall caving has been developed for coal seams with dips of 0 to 1.6 rad (0 to 90°). Those with the greatest success will be discussed later. As noted, the development of longwall mining to its present state of the art has mainly taken place since World War II with substantial gains in the last ten years. Mechanized longwall has been the result of several re¬lated major innovations (Jackson, 1975) 1) Development of the flexible armored face con¬veyor which can be installed along the face and moved forward without disassembly. 2) Development of face machines such as single and double drum shearer and coal plows which operate in conjunction with the armored conveyors. 3) Development of self-advancing hydraulic roof supports which now include chocks, chock shields, and shields. 4) Reliance of caving of the immediate roof based on proper planning and development. 5) Use of pneumatic slowing to enable extraction below overbuilt areas. The most recent developments in the mining of coal by longwall in the US include the introduction of shield supports at Kaiser's York Canyon mine in New Mexico, single-entry longwall development at Kaiser's Sunnyside mine, and Mid-Continent's advancing longwall system in Colorado. Metal and nonmetal longwall systems in the US have included the mining of copper at White Pine, MI; uranium in Utah and New Mexico, and trona in Wyoming.

Jan 1, 1982

By R. R. Hall

Tests were conducted to assess the potential of column flotation for beneficiation of a talc ore from Montana. This ere contained approximately 80% talc, with the gangue comprised mainly of chlorite, silica, and dolomite. A tributylamine, MIBC, and sodium silicate reagent suite proved effective for talc flotation. Rougher-cleaner column flotation in a continuous open-circuit produced a final talc concentrate which contained 0.90% Al2O3. 0.17% CaO, and 1.28% Fe2O3. These analyses represented impurity rejections of 77, 85, and 65%, respectively. Weight recovery for this open-circuit was 52%; however, weight recovery was estimated to be 75% with cleaner tailings recycle. Results from this investigation show that column flotation is a viable means for beneficiating talc.

Jan 1, 1990

By Kevin Andrews, Zach Agioutantis

Analysis of Coal Pillar Stability (ACPS) software, released in 2018, integrates numerous empirical pillar design techniques. The ACPS program incorporates methodologies originally available as design tools from the National Institute for Occupational Safety & Health (NIOSH), including Analysis of Longwall Pillar Stability (ALPS), Analysis of Retreat Mining Pillar Stability (ARMPS), Analysis of Multiple Seam Stability (AMSS), and concepts including Coal Mine Roof Rating (CMRR), the Mark-Bieniawski pillar formula, and pressure arch loading. The design methodologies that are the basis of ACPS were developed via analysis of significant amounts of real-world data and have been standards of the United States coal industry for decades. While there are empirical factors built into ACPS, making it ideal for use in U.S. coalfields, the concepts in the program have proven to be applicable in variable mine settings, and the software was developed to allow for user-based, site-specific modifications of key design inputs. Application of ACPS to cases outside the regions for which it was developed must be approached carefully, and continuous development of site-specific data is mandatory. A case study is presented involving the application of ACPS to assess pillar stability and assist future design for an underground lignite mine in Eastern Europe. Assessment of in-mine observations, review of the geology of the lignite mine, and evaluation of specific conditions associated with a failure event resulted in “calibration” of key input factors to ACPS. Scenarios evaluated with ACPS suggest that pillar strength and overburden depth are key factors for the determination of pillar stability and design in future areas.

Jun 25, 2024

By Laszlo Valentyik

The wide scale acceptance of the heavy media separation is due to its simplicity and efficiency. The two most important variables of the process are specific gravity and consistency of the medium. The latter is a function of the settling rate of the media solids. The almost always present clay in the feed and conse¬quently in the medium acts as a stabilizing agent, and its optimum concentration varied between 3-4%.(1,2) Since polymers essentially perform the same function in oil well drilling muds - i.e. to suspend cuttings during drilling - as the fine clay in heavy media separation, this led to the investigation of whether polymers could be used in heavy media separation as supporting agents. During the first phase of the work, it was found that by the controlled addition of polymers, the stability of the heavy media increased without unduly increasing viscosity of the suspensions, thus yielding conditions for more effective and efficient separation. The results of the experiments were reported in a paper at the AIME Centennial Annual Meeting, March 1971.(3) This paper presents the results of the experiment carried out during the second phase of the work.

Jan 1, 1975

By Adam Bedell, Paul Derby, Brad Crenshaw

Modified contact grouting was introduced almost 15 years ago as a methodology combining traditional contact grouting and consolidation grouting to address groundwater infiltration into hard rock tunnels that utilize cast-in-place concrete as permanent tunnel support. This process has been used on additional tunnels (since initially presented) as a measure to mitigate both groundwater infiltration and exfiltration. During this time, self-sealing grouts have been developed and have been added to the process to further reduce groundwater infiltration that occurs through cracks and discontinuities within the concrete liner itself. This modification is presented and additional results from the grouting process are discussed.

Jun 13, 2021