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By Murat Erdemoğlu, Turan Uysal, Thierno Saidou Barry, Mustafa Birinci

The rapid development of the global alumina and aluminum industry is straight coupled with the demands and the needs of these materials. Nowadays, the only well-known accessible resources to produce alumina and aluminum are bauxite ores. But bauxite ores are limited, and the remaining exploitable reserves do not have high contents in alumina. In countries where there is little or no bauxite reserves or where the recovery of existing bauxite ores to produce alumina with the Bayer process are not economic, alternative resources for alumina have been explored. The most attractive resources for replacing bauxites are aluminosilicate clay minerals and coal fly ash. The important processes developed for the recovery of alumina from these sources are acid leaching and alkaline leaching processes. The acid leaching is known as the most efficient in which thermal and mechanical activation are included for improving the performance of the process. The objective of this review is to give a comprehensive insight on the production of the alumina from thermally or mechanically activated clays and coal fly ash by hydrochloric, sulfuric, and nitric acid leaching processes.

By S. Gallagher, A. Mayton, R. Merkel

The prolonged exposure of equipment operators to shock and whole-body vibration (WBV) is linked to cumulative back, neck and abdominal disorders. In low coal mines, space restrictions make it difficult for seat suspensions to isolate operators from shock and WBV. Researchers at NIOSH's Pittsburgh Research Laboratory are responding to these issues by investigating viscoelastic foams. For the full-load case, an ergonomic seat made with viscoelastic foams can isolate the shuttle-car operator from shock at 15 Hz. Researchers used results from additional foam testing using an analytical model to identify viscoelastic foams that provide shock isolation at a frequency below 5 Hz.

Jan 1, 2000

By A. A. Terchick

It has been reported in the literature that there is a substantial economic incentive for removing sulfur from coal. Therefore, U. s. Steel initiated an investigation to determine the feasibility of lowering the sulfur content of its Pittsburgh-seam coal. Preliminary crushing and washability studies on a representa-tive sample indicated that substantial sulfur reductions could be attained. Figure 1 shows the effect of the top size of a given coal sample on the sulfur content of the float-l.45 specific-gravity fraction of coal. At a top size of 3 inches, the raw-coal sulfur content of 2.32 percent was reduced to 1.64 percent. Crushing to a top size of 20 mesh reduced the raw-coal sulfur to 1.25 percent. Below a top size of one inch, the sulfur content decreased rapidly as top size was decreased. Figure 2 shows the effect of specific gravity of separation on pyritic sulfur. Normally this coal has an organic-sulfur content of approximately 1 percent. As expected, pyritic sulfur was reduced as the separating gravity was lowered for all the various size fractions shown. The rate of decrease in pyritic sulfur was gradual above 1.45 specific gravity, but great below 1.45. Greater sulfur reductions were attained on the coarser sizes with decreasing

Jan 1, 1971

By V. E. Housman

EPA's Office of Solid Waste (OSW) is developing a program, under Subtitle D of the Resource Conservation and Recovery Act (RCRA) to regulate the management of non-coal mining wastes. In May 1988. OSW produced a "Strawman", which is a working document that is precursor to a proposed rule. OSW has been working closely with environmental groups, industry, and States to solicit comments and feedback on the mining waste program. OSW currently plans to release a second "Strawman" in early 1990. A proposed rule is tentatively scheduled to be published in the spring of 1991.

Jan 1, 1990

By C. D. Wittreich

The University of Idaho, Department of Metallurgical and Mining Engineering, through the Generic Mineral Technology Center, has been engaged in mine design research at the Lucky Friday Mine, Mullan, Idaho. The purpose of the research is to develop and implement the longwall underhand cut-and-fill mining method for conditions at the Mine. The longwall underhand cut-and-fill mining method involves backfilling mined stopes with a compacted tailings-cement mix. After the backfill has been allowed to cure, mining is resumed from underneath. Horizontal stresses in the Lucky Friday Mine are exceptionally high and rock bursts are a common problem. Beus and Chan (1980) have reported a 2:1 horizontal to vertical stress ratio at the mine with a 65-MPa (9,500-psi) maximum horizontal stress at the 1,295-m (4,250-ft) level. Using this mining method under these stress conditions, it is desirable to have a backfill material that has sufficient strength to safely carry the high horizontal wall loads while minimizing external steel supports.

Jan 1, 1987

By H. Kimura

A new technology for ironmaking based on direct gaseous reduction of iron ore concentrate is under development. The process is based on the flash reduction of the concentrate particles in a gaseous reducing agent, such as hydrogen, natural gas, a reducing gas generated by partial combustion of coal, or a combination thereof. This technology is expected to drastically lower CO2 emission and reduce energy consumption by about 38% of the blast furnace requirements. The energy savings are possible largely due to the elimination of pelletization and cokemaking. Process design and simulation using hydrogen as the reductant for iron ore concentrate have been performed. A process flow sheet composed of a flash reactor, heat recovery system, water removal system for purifying recycled hydrogen, and all connecting streams was evaluated using the METSIM software. Ironmaking using two reactors was also designed and simulated, which could reduce the total required amount of hydrogen although it would increase the complexity of the flow sheet and operation.

Jan 1, 2010

By Brent K. Nelson, D. Lee Petersen, Charles R. Nelson

INTRODUCTION Tunnels are commonly constructed in the very weak St. Peter sandstone in the Twin Cities area of Minnesota. Historically, core recovery in this weak sandstone was very small in the critical weaker strata resulting in little preconstruction information on the ground conditions. Improved core recovery techniques have been utilized for recent projects, allowing rock quality rating methods to be developed for the recovered core. Down-the-hole tests, and the use of combination ratings between different types of core data provide for more detailed characterization of ground conditions. THE ST. PETER SANDSTONE The 45 m thick St. Peter is an unusually pure quartz sandstone. It underlies all the Twin Cities area, except where it has been eroded by the present day Mississippi River or by pre-glacial rivers. It forms conspicuous steep bluffs along the Mississippi River where the upper Platteville limestone formation protects it from erosion. Where the Platteville formation is missing, the sandstone slopes are often more gentle. Natural case hardening of the exposed sandstone bluffs often forms a resistant crust and reduces sloughing. This case-hardened surface is not representative of the sandstone back from the bluff.

Jan 1, 1987

By Yi Luo, Jian Yang, Hua Jiang

Surface subsidence events induced by underground longwall coal mining operations can cause various disturbances to surface structures ranging from integrity and stability to functionality problems. Highway bridges, as a kind of special road construction that can only tolerate smaller movements and deformations than road pavements, are particularly susceptible to severe influence caused by subsidence-induced ground movements and deformations. However, based on accurate subsidence prediction and correct influence assessments, efficient and effective mitigation and remediation measures can be designed and implemented to ensure the continuous service of bridges, safety of the travelers and smooth mining operations. In this paper, based on the predicted final and dynamic surface movements and deformations, the techniques to assess subsidence influence on the integrity, stability and functionality of bridge structures (e.g., decks, beams, abutments, etc.) are presented. A number of mitigation measures to protect the bridge structures are recommended along with an actual application case.

By Ramiro da Conceição do Nascimento, Horst Guenter Feldhagen, Rafael Piumatti de Oliveira

Mixed hydroxide precipitate (MHP) is a nickel intermediate product that has economical benefits to downstream leaching of lateritic marginal ores. Usually, this product is subsequently processed and refined to produce nickel by hydrometallurgy, but an alternative route can be made integrating hydrometallurgy and pyrometallurgy. Assessing the overall consumption of ferroalloys to obtain stainless steel, as an increasing practice performed in China, the synergy of nickel extraction from laterites by leaching and precipitation asMHP with the production ofMHP agglomerates applied as rawmaterial to furnaces of ferronickel production is a very attractive practice. This work aims to further the technological development of an agglomerated product feasible to hydro-pyro integration. The agglomeration experiments were performed by traditional pelletizing (firing the pellets) and cold bonded pelletizing (aging the pellets by appropriate stocking). Appropriate compositionswere prepared withMHP, additives and binders for each of these routes. A specific study of binder composition was made to find an adequate melting point. The produced pellets were tested to prove their properties by crushing strength tests. The standardization applied to iron ore was followed. The best result of crushing strength was 98.52 daN/pellet. The agglomerates with approved crushing strength for use in electric furnaces were smelted to produce alloys containing nickel; the agglomerates were characterized by scanning electron microscopy. The alloy obtained was metallic ferronickel with sulphide precipitates. Therefore, MHP pellets can be precursors of nickel alloys, which have to be refined to obtain the desirable composition.

Jul 6, 2020

By Jorgen Elbrond

The capacity calculation of complex transportation systems involving variable activity times such as encountered in the mining industry are often worked out by means of simulation, which reconstructs waiting times and cycle times. The queuing theory, which mathematically calculates waiting times, has been used mainly to describe the, phenomena. This is due partly to the difficulties encountered in modelling complex systems and partly to the difficulty of reconciling the required time distribution laws with the real phenomena by means of the queuing theory. It is, however, obvious that formulas for capacity calculations would be preferable to simulation procedures because of their higher calculation speed, shorter and more flexible programs and shorter programming work. The calculation procedure presented in this paper is composed of some rather simple models, which are based on the queuing theory, and on some probabilistic and some deterministic considerations. The models are supported by observations, and to some extent by simulations. It has been attempted to find all the components of the cycle time and to include them in a comprehensive model. It is the intention to demonstrate that even quite complex mine transportation systems can be treated by means of the queuing theory with the advantages mentionned above and, without sacrificing the precision of the estimates. The speed of calculation of a wide range of parameter combinations is such that the procedure can be used extensively by a project engineer in the search for optimal modifications of the entire transportation system.

Jan 1, 1979

By T. BACHMANN, G. SHAPLAND, E. Amini, N. BEATON, M. BECERRA

In this study, several methodologies to manage low grade and often competent portion of the ore have been proposed and tested in lab, pilot and operational scales. Relevant to this subject, the Cooperative Research Centre for Optimising Resource Extraction (CRC ORE) has developed Grade Engineering® (GE) concept to modify feed streams by rejecting the low grade and possibly hard components in the stream at the early stages of a value chain. Application of GE requires to understand the impact of the process on the value chain as they are value modifiers on in situ opportunities. Traditional modelling approaches and tools do not have the ability to run the analysis in a block model scale with high fidelity in an integrated value chain. Integrated Extraction Simulator (IES) in conjunction with sophisticated analytical tools such as a neural network (NN) was used to develop and reconcile a fully integrated value chain. The value chain model makes it possible to run all available blocks in the Geomet block model, which could be several millions, under possible scenarios for Grade Engineering for economic evaluation analysis and mine planning.

Sep 16, 2020

By Ken Wangerud

The benefits of historic mining to this country have been many, but have come at a cost to the environment that has only begun to be understood over the past twenty years. While estimates vary, it is generally recognized that there are over 200,000 inactive and abandoned hardrock mines, with most of them located in the western U.S. Only a fraction of them are believed to be sources of metal releases with significant adverse environmental effects to the watersheds and receiving streams. State water-quality and natural resource management agencies have noted that hundreds of miles of streams are metal-impacted, and the aggregate effects of these sites within watersheds and drainage basins is poorly understood. Resources for the environmental assessment of abandoned mine land (AML) sites and watersheds have been and continue to be limited. Few hardrock mining states receive substantial reclamation funds under the (coal) Surface Mining Control and Reclamation Act. EPA Region VIII (EPA8) has an estimated 90,000 abandoned mining, milling and smelter sites, mainly in Colorado, Montana, South Dakota, Utah and Wyoming. An estimated 13,000 of the sites may have metal releases causing Clean Water Act and CERCLA non-compliance. Results of inventories by states and federal land managing agencies, indicate it is plausible that only 3,000-4,000 of these sites may be causing significant environmental degradation.

Jan 1, 1999

By H. S. Duzgun, N. Demirel

Estimating productivity of a walking dragline is of paramount concern to mining engineers and mine planners. Risk based evaluation of the dragline productivity is a valuable tool to estimate the dragline’s long-term availability, to develop preventive maintenance plans and to make future projections about the dragline’s performance. This paper aims to provide mining professionals with an overview of risk assessment methodology for productivity of two walking draglines, Page 736 and Marion 7820, which have been operating in the Tunçbilek openpit coal mine of Turkish Coal Enterprises (TKI) in Turkey. The study encompasses three main stages: (i) acquiring of monthly maintenance records, operating hours, mechanical and electrical failure hours between 1998 and 2009; (ii) reliability modeling using mean time between failure data and (iii) determining hazard rate and consequences to compute risk associated with dragline productivity. The results showed that that Page 736 (15.29 m3) seemed to be more reliable and less likely to fail when compared with Marion 7820 (30.58 m3). The operating hours without failure range from 41 to 51 hours with 50% reliability.

Jan 1, 2011

The Functional Performance Equation for ball milling circuits provides plant staff with a new means to improve circuit performance. However, successful execution of a plant project, with verifiable circuit processing performance improvements, requires a significant number of accompanying steps beyond the equation alone. In order to identify and articulate all these steps, a study with plant staff from two milling operations and a grinding media supplier was undertaken. ?Task analysis? of improving plant grinding performance was carried out. This analysis called for the development of a number of system components, and ultimately yielded a ?Plant Grinding Circuit Processing Performance Management/Improvement System.?

Feb 23, 2014

By M. Li, W. R. Reed, J. P. Rider, J. D. Potts

"The National Institute for Occupational Safety and Health (NIOSH) has recently developed a series of validated models utilizing computational fluid dynamics (CFD) to study the effects of air-blocking shelves on airflows and respirable dust distribution associated with medium-sized surface blasthole drill shrouds as part of a dry dust collector system. Using validated CFD models, three different air-blocking shelves were included in this study: a 15.2-cm (6-in.) wide shelf; a 7.6-cm (3-in.) wide shelf; and a 7.6-cm (3-in.) wide shelf at four different shelf heights. In addition, the dust-collector-to-bailing airflow ratios of 1.75:1, 1.5:1, 1.25:1, and 1:1 were evaluated for the 15.2-cm (6-in.) wide air-blocking shelf. This paper describes the methodology used to develop the CFD models. The effects of air-blocking shelves and dust-collector-to-bailing airflow ratios were identified by the study, and problem regions were revealed under certain conditions. The simulation results could be used for future development of dust control methods, particularly to address respirable silica dust, for a surface mine blasthole drill shroud.INTRODUCTION Surface blasthole drilling can generate considerable amounts of respirable silica dust. These high dust concentrations can be exacerbated by the high silica content as drilling cuts through silica-bearing materials such as sandstone and shale, causing overexposures for miners to respirable silica dust. These overexposures can lead to silicosis, an occupational lung disease that has no cure and is often fatal. A review of the Mine Safety and Health Administration (MSHA) respirable silica dust sample database from 2010 to 2016 for metal/nonmetal mining shows the following overexposure rates for occupations related to blasthole drilling: • 14.1% of rotary air drillers were overexposed to respirable silica dust (22 out of 156 samples) • 5.8% of rotary drillers were overexposed to respirable silica dust (9 out of 155 samples) • 7.3% of drill helpers were overexposed to respirable silica dust (3 out of 41 samples) • 7.5% of blaster/shotfirer were overexposed to respirable silica dust (3 out of 40 samples) Of significant interest is an x-ray surveillance study recently completed under the NIOSH Enhanced Coal Workers’ Health Surveillance Program (ECWHSP). This program offered free chest radiographs to surface coal miners in 16 states. Pneumoconiosis was found among 2.0% of the 2,328 screened miners with at least 1 year of mining tenure. Twelve miners had radiographic changes consistent with progressive massive fibrosis, and 9 of these 12 miners reported no underground mining tenure. All but 1 of the 9 miners worked at occupations that were in the vicinity of blasthole drilling, either as a driller, blaster, or blast crew member [1]."

Jan 1, 2018

By M. Li, W. R. Reed, J. P. Rider, J. D. Potts

The National Institute for Occupational Safety and Health (NIOSH) has recently developed a series of validated models utilizing computational fluid dynamics (CFD) to study the effects of air-blocking shelves on airflows and respirable dust distribution associated with medium-sized surface blasthole drill shrouds as part of a dry dust collector system. Using validated CFD models, three different air-blocking shelves were included in this study: a 15.2-cm (6-in.) wide shelf; a 7.6-cm (3-in.) wide shelf; and a 7.6-cm (3-in.) wide shelf at four different shelf heights. In addition, the dust-collector-to-bailing airflow ratios of 1.75:1, 1.5:1, 1.25:1, and 1:1 were evaluated for the 15.2-cm (6-in.) wide air-blocking shelf. This paper describes the methodology used to develop the CFD models. The effects of air-blocking shelves and dust-collector-to-bailing airflow ratios were identified by the study, and problem regions were revealed under certain conditions. The simulation results could be used for future development of dust control methods, particularly to address respirable silica dust, for a surface mine blasthole drill shroud. INTRODUCTION Surface blasthole drilling can generate considerable amounts of respirable silica dust. These high dust concentrations can be exacerbated by the high silica content as drilling cuts through silica-bearing materials such as sandstone and shale, causing overexposures for miners to respirable silica dust. These overexposures can lead to silicosis, an occupational lung disease that has no cure and is often fatal. A review of the Mine Safety and Health Administration (MSHA) respirable silica dust sample database from 2010 to 2016 for metal/nonmetal mining shows the following overexposure rates for occupations related to blasthole drilling: • 14.1% of rotary air drillers were overexposed to respirable silica dust (22 out of 156 samples) • 5.8% of rotary drillers were overexposed to respirable silica dust (9 out of 155 samples) • 7.3% of drill helpers were overexposed to respirable silica dust (3 out of 41 samples) • 7.5% of blaster/shotfirer were overexposed to respirable silica dust (3 out of 40 samples) Of significant interest is an x-ray surveillance study recently completed under the NIOSH Enhanced Coal Workers’ Health Surveillance Program (ECWHSP). This program offered free chest radiographs to surface coal miners in 16 states. Pneumoconiosis was found among 2.0% of the 2,328 screened miners with at least 1 year of mining tenure. Twelve miners had radiographic changes consistent with progressive massive fibrosis, and 9 of these 12 miners reported no underground mining tenure. All but 1 of the 9 miners worked at occupations that were in the vicinity of blasthole drilling, either as a driller, blaster, or blast crew member [1].

Jan 1, 2019

By E. Rubenstein, V. Gangrade, K. V. Raj, M. L. Harris

Underground stone mine ventilation is characterized by large openings with low resistances. These mines primarily face three challenges: moving adequate volumes of air, controlling and directing the airflow, and planning ventilation systems that work well with production requirements. Given these challenges, this paper examines the data collected by the Mine Safety and Health Administration (MSHA) to determine the extent to which respirable crystalline silica (RCS) and diesel particulate matter (DPM) are an issue in underground stone mines. Out of 522 sampled mines, there were 108 personal samples exceeding the RCS Permissible Exposure Limit (PEL) during 2000–2020. DPM were more prevalent than RCS in these mines with 382 personal samples exceeding the DPM PEL out of the 929 mines sampled during 2002–2020. Dilution of DPM is usually the defining parameter for design of mine ventilation systems in largeopening underground stone mines. With this knowledge, focused attention can be directed to these mines so that appropriate prevention and mitigation techniques can be utilized to prevent stone miners’ exposure to RCS and DPM and subsequent respiratory diseases.

Mar 2, 2022

By C. M. Liu

"The Freeport-McMoRan Sierrita Crystal Plant produces Copper (II) Sulfate Pentahydrate (CuSO4·5H2O) through a series of cooling crystallizers. In this process, high supersaturation and unwanted spontaneous nucleation promote fine crystals. Seeding through recycled crystal classification can manipulate the crystal size distribution (CSD) for larger crystals. Proper selection of the crystallizer for seeding can prevent spontaneous nucleation and promote final crystal size. This study shows when seeding temperature is closer to the crystallizer temperature, suspension densities in the crystallizers are promoted and overall CSD shifts to a larger size of crystals. INTRODUCTION Figure 1 shows an overview of the crystallization process. The in-plant feed flow, called Pregnant Mother Liquor (PML), enters the first crystallizer and is subsequently cooled through a series of four crystallizers. Specific temperatures are targeted for each crystallizer to ensure the crystallization process is operating within the metastable zone (MSZ). The discharged flow from crystallizer #5 then enters two cyclones. The overflow from the cyclones contains smaller crystals providing seed crystals for crystallizer #5. The underflow from the cyclones begins the drying process. The overflow from crystallizer #5 enters cyclone #3 for removal of fine crystals and seeding purposes. The underflow from cyclone #3 has the capability to provide seed crystals for crystallizer #1 or crystallizer #2. The overflow leaves the system as Spent Mother Liquor (SML). Undersize crystals dissolve into the PML and return back to crystallizer #1.THEORIES AND METALLURGICAL TESTS Seeding requires an understanding of the crystal size, solution temperature and amount of crystals that enter the crystallizers (1). For the seed crystal size, classified crystal seeds can prevent fine crystals returning back into the system which eventually leads to excessive agglomeration (2). Proper selection of the crystallizer can ensure seeding at an appropriate temperature. Seeding at a temperature much lower or higher than the saturation temperature promotes spontaneous nucleation. Typically, seeding between 4-5°F below the saturation temperature is acceptable (5). A general rule of thumb is to add the seed crystals at the temperature between the solubility curve and the metastable zone. An experiment conducted by Mettler-Toledo AutoChem, Inc. indicates seeding close to the solubility curve rather than the metastable zone promotes a lower supersaturation and nucleation rate but yields a higher growth rate and a greater number of larger crystals (1). The amount of seed crystals can not only change the suspension density but also narrows the width of the MSZ in the crystallizers. An experiment conducted by Jaroslav Nyvlt reports with the crystals absent, the maximum allowable undercooling is 6.3 degrees at a cooling rate, 5°C/hour. With the presence of crystals, it narrows the MSZ width to 2.2 degrees (4). Industrial crystallizers normally operate at suspension densities between 15% and 25% by mass. When suspension densities are lower than 15%, it increases the risk of primary nucleation and the probability of incrustations; on the other hand, if the suspension densities are greater than 25%, it can cause a greater attrition rate and increase the probability of deposits (6). Moreover, operating suspension densities between 15% and 25% are also sufficient to minimize supersaturation rate which promotes crystal growth over nucleation (2, 6)."

Jan 1, 2015

By Y. Lahaye, O. Martinsson, B. I. Palsson

"Four main and three minor rare-earth-element (REE)-bearing minerals were identified and quantified in the Kiirunavaara apatite iron ore tailings using optical microscopy, an electron probe microanalyzer (EPMA) and a mineral liberation analyzer, and their chemical compositions were analyzed by the EPMA and laser ablation inductively coupled plasmamass spectrometry. REEs are shown to be contained in the minerals apatite, monazite, allanite, titanite, zircon, thorite and synchysite. In zircon, thorite and synchysite, they occurred in only trace amounts and contributed limited amounts to the total REE budget, and these are consequently of minor importance. Monazite occurred as inclusions in apatite and as free particles, 90 percent liberated. Allanite occurred to some degree in mixed grains with magnetite but also as free particles. Monazite mainly reported to the apatite concentrate, while allanite and titanite largely went to the tailings, the latter preferably to those fractions smaller than 38 µm. The amount of titanite in the finest tailings fraction was 2.3 weight percent, containing close to 1 percent REEs, with heavy rare earth elements (HREEs) making up 28 percent of the total REEs. However, a texturally distinct group of titanite grains showed an HREE/REE ratio of up to 67 percent. Furthermore, titanum dioxide analyses indicate that titanite is preferentially released into the tailings from the secondary magnetic separation step in the concentrator. Our data therefore suggest that titanite, occasionally enriched in HREEs, can be extracted from the processing stream and might thus be considered a new source for REEs at Kiirunavaara and similar deposits.IntroductionDeposits of apatite iron ores are the major source for iron in the European Union and are exploited by Luossavaara-Kiirunavaara AB (LKAB) in several mines in the Kiruna-Malmberget area in northern Sweden. Kiirunavaara is the largest of the apatite iron orebodies in Sweden, comprising more than 2 Gt of iron ore with 60 to 68 percent iron (Fe). At the end of 2015, the total accumulated production of crude ore from openpit and underground mining since the start of mining was 1,566 Mt, with ore reserves of 644 Mt grading 46.3 percent Fe (LKAB, 2016). The deposit defines a steeply dipping tabular body, approximately 6 km long and up to 180 m thick, extending at least 1,500 m below the surface. It is situated in the middle part of the Palaeoproterozoic Kiirunavaara Group of volcanic rocks and follows the contact between a thick pile of trachyandesitic lava and overlying pyroclastics (Martinsson, 2004)."

Jan 1, 2017

By J. Chai, Q. Yuan, B. Qiu

"Overburden strata deformation monitoring is one of the key problems in ground control. Using geophysical method through surface drilling to detect strata deformation is commonly used in the industry. In this paper, a geophysical method based on the distributed optical fiber sensing (DOFS) system were conducted in the laboratory, where a DOFS-based strata deformation monitoring experiment was performed with three physical models. The results show that the DOFS method precisely detects the rock mass deformation and strata structure forming with the Brillouin frequency shifts (BFS) representation. The BFS curves are divided into three phases, which reflects the horizontal three zones developed in the overburden. The BFS distribution presents a multiple stages form, the 1st stage corresponds to the caving zone and the 2nd stage corresponds to the fracture zone. Based on the multiple stages form, the evolution of the water flowing through fractured zone have been determined and the controlling effect of key strata over the water flowing fracture has been pointed out. In the end, the comparison validation proves the accuracy and reliability of this method, and it could be a new approach for the ground control research. INTRODUCTION Overburden rock strata above the work face space will propagate from slight deformation, part destruction to violent movement because of the underground coal mining. It is fundamental and an intrinsic requirement of ground control to monitor the mining-induced rock mass deformation.[1] Overburden strata have their significant mechanical behaviors and movement under damage deformation and fracture. Overburden strata deformation affect the mining ground pressure control directly, and performance in the relationship of supporting equipment and the surrounding rock, the mining-induced fracture distribution and the loss of underground water resource, the ground surface structure stability and the ecological environment.[2] From the perspective of the concept of safe and efficient scientific coal mining: the overburden strata deformation is an important part of mining method selection and reasonable supporting solutions decision which can solve the issues like the roof supporting force calculation, overburden fracture distribution and gas drainage, ground subsidence, separation of coal and rock control and top-coal recovery rate and so on. From the perspective of green and ecological mining: the overburden strata deformation is the key basis of studying the mining-induced ground subsidence and mining area ecological damage, and such engineering problem like environmental protection in mining area, ecological restoration in mining subsided land and the water conservation in fragile ecology area of mining could be solved based on it.[3-6] Therefore, the mining-induced overburden strata deformation is the key of ground control and needs to be controlled artificially."

Jan 1, 2017