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By G. Hoffmeyer, I. Ream

"Several copper projects exclusively utilizing in-situ recovery methods are currently under development in Arizona. Favorable conditions for In-Situ Copper Recovery (ISCR) include a saturated orebody, fracture hosted mineralization, hydraulic conductivity sufficient to effectively inject and recover solutions using wells, and a relatively flat background hydraulic gradient. Safe operation of an ISCR project requires that the operator have the ability to induce and maintain localized hydraulic gradients, thereby controlling the movement of injected and recovered solutions. Benefits of ISCR include reduced initial capital, and a greatly reduced environmental footprint. THE ISCR METHOD EXPLAINED The method chosen to extract a mineral from a deposit is driven by characteristics such as its size, grade and depth of burial. Large lower grade deposits that require significant excavation to access using surface methods are potential candidates for in-situ recovery. ISCR may also be ideal for smaller deposits due to the lower initial capital. However, regardless of the size of the deposit, certain hydrogeologic conditions must be present for ISCR to be successful. In-situ recovery methods do not require excavations of rock from the surface or underground, resulting in a dramatic reduction in surface disturbance when compared to conventional mining. With the ISCR method, what is visible above ground is the processing plant, well heads, piping, process solution impoundments and evaporation ponds. There are no waste rock piles, tailings impoundments, leach pads, or impacts associated with blasting and hauling. Other benefits include reduced initial capital, reduced dust and noise, and lower water use. Early testing of the in-situ copper recovery method by Occidental on the Van Dyke deposit east of Phoenix and by Kennecott at Safford Arizona in the 1970s produced encouraging results, but the permitting regime for a large-scale operation was not yet in place. Additional testing and commercial application of in-situ copper recovery techniques have expanded since the 1980s, most commonly in conjunction with open pit or underground mining operations. For example, several operations in Arizona (San Manuel, Miami East and Tohono) have used in-situ techniques to extract additional copper following conventional mining from parts of the deposits adjacent to open pits or underground workings. Where the rock has been broken up by conventional methods, the method is called “in-place” leaching. The US government has also been involved in assessing in-situ techniques. For example, joint research was conducted by the US Bureau of Mines and industry on the Santa Cruz deposit in Arizona; and both federal and state agencies have been involved to establish the comprehensive permitting regime that exists today. Currently there are several projects in Arizona being evaluated as stand-alone ISCR operations."

Jan 1, 2016

By R. L. Grayson

In 1995, Congress abolished the Bureau of Mines in the Department of Interior but preserved the safety and health research functions being performed at the Pittsburgh and Spokane Research Centers. These functions were transitionally housed in the Department of Energy before permanently merging with the National Institute for Occupational Safety and Health (NIOSH), Department of Health and Human Services, in October 1996. Since the merger of the former Bureau with NIOSH, there has been an active evaluation of ongoing research activities, significant interaction with stakeholders, and the development of a process leading to "data informed" priority setting. This presentation will review current surveillance information concerning the level of injury and disease from mining work and will discuss how research priorities are evolving to improve the contribution of research to the prevention of injury and disease.

Jan 1, 1998

By H. J. Brown

Pluess-Staufer (California) Inc. Lucerne Valley California operation is one of the largest producers of high brightness high purity fme grind limestone products in western North America. The San Bernardino Mountains area of southern California contains the largest high brightness, high purity limestone mining operations and undeveloped reserves in western North America (Fig. 1, Brown 1987). Combined annual production of high brightness limestone products from several operations is approximately 1.5 million tons, with an estimated gross value of $75 million dollars per year (Fig. 2). An additional 5.0 million tons of cement grade limestone is mined by several large cement producers in the nearby Mojave area (Brown, in press). The purpose of this paper is to summarize the geologic setting, genesis and mining of white, high purity crystalline limestone by Pluess-Staufer (California) Inc.

Jan 1, 1994

By J. Larsson

In the pursuit of increased safety the mining industry has worked to develop systems for remote control and autonomous operation of both stationary and mobile equipment. This paper reports on a newly developed system for teleoperation and autonomous tramming of LHD (Load-Haul-Dump) mining vehicles that not only increases the safety of the operators, but also has the potential to increase productivity.

Jan 1, 2010

By Ernest F. Giovannitti

A couple of years ago, one of the major television networks produced a series on the environment. One episode in the series dealt with the nation's solid waste problem and some of the research being done to solve it. It was interesting to listen to one researcher who was attempting to develop a glass that when broken would dissolve in water. It was said that using this glass would eliminate over 100 million tons of solid wastes each year. At first glance, it would appear that this research-effort would make a significant contribution to environmental pollution control; however, if one pauses to consider the water, he can see that this solution to the solid waste problem may well contribute to a water pollution problem. The dissolved material must either end up in our surface streams or be removed in waste treatment systems. Either alternative may have a more adverse effect on the environment than the original problem. With today's emphasis on the environment, it is important that the effects of our activities be studied in depth. Then, by properly planning the activity, the adverse effects can be minimized. The coal mining industry 100 years ago was in the same boat, as our glass maker, is today. Unfortunately, it too failed to consider all the effects of its activities and as a result, in Pennsylvania, there are over 5000 miles of streams adversely affected by coal mine drainage. The situation is improving, however, because mine operators are beginning to recognize and accept the methods for controlling coal mine drainage. The purpose of this paper is to discuss the measures for the control of coal mine drainage and to set forth the factors that affect these controls.

Jan 1, 1972

By Nicholas Tabor, Norbert Fuegenschuh, Richard Taylor, Jean-Marc Wehrli

The Plymouth Tunnel forms part of the 16-mile long route of the Purple Line Light Rail Project promoted by the Maryland Transit Administration. The tunnel is approximately 1,220 feet in length with a shallow vertical alignment located beneath a residential area. Challenging mixed ground conditions included surficial soils, decomposed Saprolite, and highly weathered to fresh rock requiring the use of the Sequential Excavation Method (SEM) for construction. This paper discusses innovative approaches implemented during construction as well as challenges faced during planning and installation of a spray-applied permanent concrete liner.

Jun 13, 2021

By Ali Keneti, Xavier Ryan, Gerardo Sanchez, Shannon Goff

In this study, FLAC3D modeling was conducted for ground-structure stability assessment for a pilot tunnel passing under a large shaft excavated in the vicinity of existing structures at Karangahape Station for the City Rail Link Project in Auckland, New Zealand. The analysis involved generation of the geometries and construction sequences in Rhinoceros®, modeling the existing ground condition, calibration of the simulated in situ conditions with the observed behavior of the ground, and excavation of the shaft and the pilot tunnel. A comprehensive interpretation of the results was then performed accompanied by comparison of the predicted behavior with the observed response of the ground during construction.

Dec 1, 2022

By J. A. Marts

Reservoir properties including porosity and permeability distributions in longwall coal mine gobs have direct application to modeling the flow patterns and gas distributions in the gobs. Proper assessment of these distributions is required to assess gob gas hazards such as spontaneous combustion and explosive methane mixtures and to optimize gob gas venthole operation and nitrogen inertization. Determining the reservoir properties is difficult given that the gob is inaccessible and direct measurements cannot be easily taken. Several techniques had been used by previous researchers and will be discussed. This paper will present the methodology used to model the gob compaction by simulating the sequential extraction of coal. Two Western US coal mines were used for case studies. By determining volumetric strain, the porosity and permeability distributions in the gob can be calculated. The geo-mechanical model predicts an axisymmetric volumetric strain distribution with a steeper slope near the start-up room and a shallower slope near the active face.

By S. M. Hossaini, M. Ataei, H. Moosavi

The abstract highlights the importance of pillar stability in underground coal mines and the influence of rock mass strength and joint orientation on pillar behavior. The study employs numerical modeling using the distinct element code (UDEC) to investigate the impact of these factors on pillar stability. The research considers different joint orientations and varying rock mass strengths, analyzing parameters like stress distribution, displacement, and failure patterns. The findings reveal that both joint orientation and rock mass strength significantly affect pillar stability, with specific combinations leading to reduced safety factors and increased deformation. The study concludes by emphasizing the importance of considering these factors in pillar design for safe and efficient mining operations.

Apr 4, 2022

By Russell Frith

A review of published literature reveals case histories whereby the entire periphery of a coal pillar has “burst” out as a single event during first workings, the associated energy and material release causing significant damage to adjacent roadways and any equipment/infrastructure located within said roadways. Such events are distinct from coal burst events during first workings such as that at the Austar Mine in 2014, or those linked to overburden bumps related to either horizontal stress-driven slip along major faults and/or thick, massive strata units in the overburden or floor of the coal seam.

By David J. Hatem, K. Bhattarai

The increasing popularity of alternative methods in delivery of underground infrastructure projects has given rise to innovative and collaborative contracting strategies to allocate and manage the unique risks associated with the work. This paper presents approaches and recent examples of how risk has been dealt with using various alternative delivery methods, including Progressive Design Build (PDB) and Construction Manager/General Contractor (CM/GC). Based on the experience gained from these examples, recommendations for an innovative and collaborative risk baselining approach using contingency sharing are presented that should advance the overall goals of equitable risk sharing and compensation.

Jun 13, 2023

By John M. Arnold

Several years ago it became apparent to some of our people that; there was developing a very definite need for largee coal reserves in the West to satisfy- the need for fuel for the furnaces of electric generating plants with the rapid development of, the West, of both population and industry, it was impossible for hydro-electrics plants to keep up with the ever increasing demand for electricity. In 1960, Mr. E. R. Phelps, then associated with the engineering department of Peabody Coal Company, began a search for and development of coal deposits in the very remote northeast section of Arizona near the village of Kayenta. Travel to this section of the country was not easy even at this late date, and it was an eight hour drive from Farmington, New Mexico to Kayenta, Arizona, a distance of some 130 miles. The trip was over roads that even' a-horse and wagon had trouble negotiating and a four wheel drive vehicle was about the only type of transportation that could satisfactorily traverse these roads, as testify many badly beaten sedans and coupes that tried it. Since that time a very excellent road has been constructed from Shiprock; New Mexico to Cameron, Arizona where it junctions with another excellent road that runs north to Page, Arizona and the Lake. Powell area and south to Flagstaff, Arizona on highway 66. Kayenta is a small village nestled at the foot of the Black Mesa near its northeast extremities. The coal deposits of interest were on the surface of the mesa. This location presented another problem, as the only trail to the top of the mesa was intended for walking, horseback, or a brave soul In a horse and wagon. Once again the four wheel drive vehicle was about the only answer. To reach the coal deposits you must climb the mesa, which is vertical ascent of some 1,500 feet, and then proceed southward into the bowl of the mesa with an ensuing descent of some 1,000 feet, finally coming to an elevation of 6,500 feet, at which elevation the coal outcrops become apparent.

Jan 1, 1969

By Wern-Ping Nick Chen

Durability risks for underground facilities can be underestimated during design phase as compared to well-known geological risks. However, unclear durability requirements can result in construction schedule delay and change orders. Unlike bridges or buildings, a unified underground durability code or standard does not exist. This paper will provide a durability approach for underground facilities, including degradation modes, mitigations, and compliance measures during construction. In addition, this paper will address how to clearly specify durability requirements in a contract document to reduce disputes during construction and discuss key durability tests that are time consuming and will impact construction schedule if not timely planned.

Jun 23, 2024

By J. E. Spencer

Mesozoic and Tertiary mineral deposits in west-central Arizona are commonly associated with Mesozoic thrust faults and Tertiary detachment faults, respectively. Quartz-kyanite rocks and pyritic quartz-sericite schists with local anomalous gold are the product of probable Jurassic argillic alteration of Jurassic volcanic, sedimentary, and plutonic rocks followed by Cretaceous thrust burial and associated metamorphism. Slivers and sheets of Paleozoic carbonates along Mesozoic thrust faults were locally sites of syn-and post-thrust mineralization. Widespread brecciation along Tertiary detachment faults resulted in increased permeability along fault zones. Elevated thermal gradients also resulted from detachment faulting and apparently caused convective aqueous-fluid circulation along detachment faults and associated Fe+Cu±Au mineralization.

Jan 1, 1988

By J. Hallowell, M. Conley, R. Cook

Inflatable friction rock bolts (IFRBs) are often considered temporary ground support due to their susceptibility to weakening from corrosion. The effective service life of an IFRB can be difficult to estimate due to the multitude of factors that affect the rate of corrosion. Some mine sites have experienced several-year-long service lives of IFRBs without issue, while others experience corrosion-related falls of ground only weeks after installation. The most common industry method of assessing bolt performance is by pull testing the fixture. However, due to the IFRB’s ability to mobilize its full tensile capacity with less than 2 feet of anchored length, corrosion along the bolt at depths greater than 2 feet from the collar cannot be identified using this approach. Alternatively, reinflation testing is a simple and non-destructive method of evaluating the condition of an entire bolt length for breaches in the bolt wall. This can be particularly useful when assessing the extent of corrosive conditions within a particular mining area where instabilities have already occurred and the condition of nearby bolts is unknown, or when re-entering historic mine workings which have not been monitored.

Feb 1, 2023

By William J. Robinson

What is the cummulative rate of recovery of copper from a sulfide leach dump? This is one of the most frequently asked questions today. We, in the industry, ask it of each other when we meet; however, the technical answers may vary from "I don't know" to 'quite good" from people within the same company. Management also poses this question because it plays a vital role in our planning for future production. The answer is difficult because of the many variables between different operations such as physical construction of the dump, topography of the original site, characteristics of dump material, mineralization, water application, etc. Each has a bearing on the rate of recovery. OPERATIONAL DATA Our method of water distribution is unique in that each dump is drilled to allow physical injection of water into the dump. The in¬jection holes are drilled vertically, on 251 centers, from the surface of the dump. Normally, the holes are drilled 40' deep and cased with 4" PVC perforated pipe.. The pipe is perforated at one-foot intervals with four V diameter holes at 901 spacing on the pipe circumference. We formerly alternated shallow holes (20'-40') with deep holes (80'-l80') in an effort to cover the entire dump and hasten oxidation. The shallow hole depth varied according to the compaction thickness. The deep hole depth varied according to the height of the dump and the original ground profile, We prefer to have the deep holes end 20'-30' above the original ground level. This generally allows us to penetrate the coarse material at the bottom of the dump. We had to discontinue the deep holes_ in order to cover more dump area in a shorter period of time to meet increased production requirements.

Jan 1, 1972

Strainburst phenomena, generally characterized by a sudden release of energy in a volume of highly stressed rock, are often encountered in such situations like crown pillar bursts in cut-and-fill mining, face bursts at development headings and floor bursts in deep shaft sinking. This paper describes a simple FE modeling approach which leads to the calculation of the energy release rate (ERR) and the total energy storage rate (TESR) in the rock mass around the openings. The merits of using such energy parameters in the analysis of strainburst problems to identify areas of high energy release/storage are discussed. However, much site-specific back analyses are needed to better understand how strainbursts and energy parameters are inter-related.

Jan 1, 1998

By Tadashi Nishida

Subsidence due to mining caused various kinds of damage to the surface structures, and actually great deal of mining damage becomes the severe social problem at some time in many coal fields, but the most of mining damage was restored at present. Recently, the effect of old coal working on the deformation of newly constructed structures has become into question, because it was obliged to plan many engineering structures in old mining areas for the shortage of adequate construction sites and the difficulty of getting location. That is, building, dams, bridges for railroads and highway, power plants, tunnels, storage tanks and so, have to be built on the ground which has old coal working.

Jan 1, 1982

By T. F. Deems

The nature, usage and comparatively rare occurrence of ball clay is described. The importance of these white firing plastic clays in ceramics, particularly in the production of industrial sanitary ware and tiles, is emphasized. The US deposits are briefly discussed. What is known about relevant deposits in Brazil, Argentina, Colombia and Venezuela (the four largest ceramic producers in South America) is also described. The ceramic plants have been sited near the centers of population rather than the plastic clay deposits. At present, extraction is probably concentrated on surface residual deposits and lenses which require minimum investment. Native plastic clays are used exclusively in the tile plants, but in sanitary ware, they are often used as extenders of imported ball clays.

Jan 1, 1997

By R. L. Bullock

The New Lead Belt of Missouri, situated in the heart of the Clark National Forest, stands as a dynamic example of how mining activities can successfully coexist in a restricted wilderness area. After 16 years of intensive drilling activity, mine development and surface plant construction, many would agree that the mine-plant design philosophy of St. Joe has minimized the imbalancing effects to the ecology and the wilderness appearance of the Ozark area. In a recent dedication speech of St. Joe's newest operation, it was stated: 1 "this Brushy Creek Mine, as well as nearly all of the mines in this district, lies within the boundaries of the Clark National Forest. Here the Forest Service has an outstanding and realistic program for multi-use of Federal lands. Mining, lumbering, recreation and conservation coexist in, what I consider, a delightful wilderness environment. I believe that this same type of usage could be permitted on all government land without seriously detracting from its natural beauty." Each and every activity in the process of discovery, exploration, development and finally operating a mine and process mill could have drastically degraded some phase of nature's environment were it not for the well developed and executed plans of the mining people involved. This is not to say that everything has been kept in perfect balance; but most certainly the industrial impact on what was once a wilderness area has been held to a minimum. What follows is the story of how each phase of this gigantic development was handed by industry people. Through their interaction and cooperation with government agencies, educators and researchers, allowed not only the ecology of the area to be protected, but the aesthetic beauty of the Ozarks to remain intact.

Jan 1, 1973