Mining_Methods_UnderGround_Mining - Mining and Blasting

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CAF fill Secondary BaCkFilling Primary Tertiary Unmined Unmined Secondary Designed stopes ROCK fill Primary Secondary stope extractio n CAF filled on side adjacent to unmined stope ROCK filled on side adjacent to mined stope Stope extraction and filling sequence at Olympic Dam. on the design, as do the fill mix and strength attainable using available ma- terials. Fill quantities will determine the size of the preparation and placement systems, and the location and eleva- tion of stope openings relative to surface facilities such as tailing dams and concentrator are major considerations. Mine planners focus on tailormade fill to save cement costs by strengthening the fill only where it is required, close to the stopes to be mined, such as at Olympic Dam. Underhand cut and fill mining sequence. Low cement content High cement content and reinforcement Slice 1 Slice 2 Slice 3 Unmined CAF fill Unmined Unmined Hydraulic fill Originally, backfill comprised waste rock, either from development or hand picked from broken ore. Some larger mines in the US quarried rock and gravitated it down fill raises to the mine workings. Nowadays, rock fill is used for filling secondary and tertiary stopes, and is usually a convenient and economic means of disposal for waste from development. The first hydraulic fills were composed of concentrator tailings that would otherwise have been deposited on the surface. The mill tailings were cycloned to remove slimes so that the contained water would decant. This fill was transported underground as slurry, composed of around 55% solids, which is the typical underflow for thickeners and is the pulp density normally used for surface tailings lines. When the grind from the mill was too fine for decanting in the stopes, alluvial sand was employed instead of tailings. Particles of alluvial sand are naturally rounded, enabling a higher content to be pumped than for hydraulic fill made from cycloned tailings. This type of fill is commonly referred to as sand fill. Many mines still employ non-cemented hydraulic fill, particularly for filling tertiary stopes. The quantity of drain water from hydraulic backfill slurry containing 70% solids is only a quarter that resulting from a 55% solids mix. The porosity of hydraulic backfill is nearly 50%. It may be walked upon just a few hours after placement, and will carry traffic within 24 hours. 44 underground mining methods Unmined Unmined Primary stope extracted CAF filled due to unmined adjacent stopes CAF fill ROCK fill Secondary stope extracted CAF filled on side adjacent to unmined stope ROCK filled on side adjacent to mined stope Hydraulic fill Slice 4 Face 1 Face 2 Unmined Unmined Unmined 2nd Primary stope extracted CAF filled due to adjacent unmined stopes ROCK fill CAF fill Tertiary stope extracted ROCK filled as no adjacent stopes
Thickener Binder cement and/or slag Paste factory – principal flowsheet. Planning considerations Paste pump Because the density of hydraulic fill is only about half that of ore, a supplemen- tary fill material will be needed when less than half of the tailings can be recovered from the mill circuit. When planning a hydraulic fill system, a major consideration is water drainage, collection and disposal, particularly on deep mines. Getting large volumes of water back to surface can be a costly exercise, and installing the infrastructure may be difficult, expensive and time consuming. Portland cement added to hydraulic fill as a binder also adds strength, and this system of fill in normal and high density is employed at many mines around the world. A portion of the cement may be substituted using fly ash, ground slag, lime or anhydrite. If cement is added in the ratio 1:30, the backfill provides better support for pillars and rock walls. If the top layer is then enriched at 1:10, the backfill provides a smooth and hard surface from which broken ore can be loaded and re- moved. Addition of cement reduces ore dilution from the fill and facilitates se- lective mining and greater recovery from both stopes and pillars. Water decanted from cemented fill has to be handled appropriately to avoid cement particles reaching the ore passes Cyclone Mixer and sumps, where they can have great nuisance value. One approach is to reduce the amount of water in the fill, increasing solids content to 65-75% and more in a high-density fill. Additives can also reduce the water decant from fill. Paste fill Vacuum filter Paste to the mine Paste fill originally used non-cycloned mill tailings mixed with cement at the stope. Coarse tailings permit a very high solids content of up to 88% to be pumped at high pressure, and high setting strengths were achieved. Paste is currently used as a replacement for hydraulic fill, with the cement added at surface. It exhibits the physical properties of a semi-solid when compared to highdensity fill, which is a fluid. Because the slimes fraction of the tailings forms part of the mix, cement always needs to be added into paste fill, with 1.5% as the minimum requirement to prevent liquefaction. Very precise con- trol of pulp density is required for gravity flow of paste fill, where a 1-2% increase can more than double pipeline pressures. Cemented rock fill Tailings from concentrator Cemented rock fill (CRF) originally consisted of spraying cement slurry or BaCkFilling Paste fill plant at Garpenberg, Sweden. cemented hydraulic fill on top of stopes filled with waste rock, as practiced at Geco and Mount Isa mines. Nowadays, cement slurry is added to the waste rock before the stope is filled. Where rock is quarried on surface, it is normally gravitated to the mining horizon through a fill raise, from the base of which trucks or conveyors are used for lateral transport underground. Advantages of CRF include a high strength to cement content ratio, and provision of a stiff fill that contributes to regional ground support. CRF is still selected for some new mines, and many operators prefer this system. Cement rich hydraulic fill was once used for mats where poor ground conditions dictated underhand cut and fill mining. Since the major cost component of backfill is the cement at a ratio of 1:2, this fill is not economical, and was replaced with ready-mix concrete with 10-12% cement content for a standard 3,000 psi, or 20 Mpa, mix. Ice fill has been used in Norway and Russia in permafrost regions. Hans Fernberg underground mining methods 45
Page 1 and 2: Mining Methods in Underground Minin
Page 3 and 4: Contents Foreword 2 Foreword by Han
Page 5 and 6: Mining TrendS Trends in underground
Page 7 and 8: Rock production (2005) Ore (Mt) noi
Page 9 and 10: geOlOgy FOr Mining geology for unde
Page 11 and 12: Sandstone. Gneiss. Many salts, for
Page 13 and 14: drives within the mineral deposit,
Page 15 and 16: Mineral prospecting and exploration
Page 17 and 18: Atlas Copco underground core drilli
Page 19 and 20: Finding the right balance in explor
Page 21 and 22: % 100 80 60 40 20 0 Canada latin am
Page 23 and 24: Mine inFraSTruCTure underground min
Page 25 and 26: pumphouses and workshops. Drill/bla
Page 27 and 28: Principles of raise boring efficien
Page 29 and 30: Typical operating installation of t
Page 31 and 32: MeCHanized BOlTing Mechanized bolti
Page 33 and 34: on the latest Boomer and Simba seri
Page 35 and 36: Mining in steep orebodies Based on
Page 37 and 38: main level, providing access and ve
Page 39 and 40: waste ratio during a typical muckin
Page 41 and 42: Mining in flat orebodies nearly hor
Page 43 and 44: crosscut drift Foot wall (The Fossu
Page 45: BaCkFilling Backfilling for safety
Page 49 and 50: History Mining has been conducted a
Page 51 and 52: 0.1% Cu, 99 g/t Ag and 0.3 g/t Au.
Page 53 and 54: This joint development process star
Page 55 and 56: zinkgruVan, Sweden Changing systems
Page 57 and 58: longhole open stoping has contribut
Page 59 and 60: flexibility during drilling and bol
Page 61 and 62: increasing outputs at lkaB iron ore
Page 63 and 64: 2 Groups of ore passes 7 Developmen
Page 65 and 66: keMi, Finland From surface to under
Page 67 and 68: The crusher station at the 560 m le
Page 69 and 70: Kemi is carrying out slot hole dril
Page 71 and 72: JelSˇ aVa, SlOVakia Mining magnesi
Page 73 and 74: Pillar between stopes 5.0 m-high, b
Page 75 and 76: kure, Turkey all change for asikoy
Page 77 and 78: m along the footwall contact, or in
Page 79 and 80: History The El Soldado and Los Bron
Page 81 and 82: Max 15.0 m Ventilation shaft 17 to
Page 83 and 84: Simba M6 C drilling radial holes. a
Page 85 and 86: Pioneering mass caving at el Tenien
Page 87 and 88: caving in primary rock. Currently,
Page 89 and 90: Production area 5 4 80 m 57,5 m 22,
Page 91 and 92: used is again panel caving with pre
Page 93 and 94: introduction Codelco, renowned for
Page 95 and 96: During pilot hole drilling and rea-
Page 97 and 98:
40 m in length were drilled each mo
Page 99 and 100:
anTOFagaSTa, CHile Modernization at
Page 101 and 102:
MOunT iSa, auSTralia Mount isa mine
Page 103 and 104:
4500N Advance south Stoping sequenc
Page 105 and 106:
to the hanging wall. The fill used
Page 107 and 108:
MelBOurne, auSTralia High speed hau
Page 109 and 110:
The Minetruck MT5010 exits from the
Page 111 and 112:
geology The Olympic Dam mineral dep
Page 113 and 114:
Activity Overview Mucking Overview
Page 115 and 116:
on site. Later stopes, which are no
Page 117 and 118:
improved results at Meishan iron or
Page 119 and 120:
ig, six hours/shift, two shifts/day
Page 121 and 122:
Mechanized mining in low headroom a
Page 123 and 124:
large scale copper mining adapted t
Page 125 and 126:
tricky, because the pillars in the
Page 127 and 128:
gerMany/SOuTH kOrea underground min
Page 129 and 130:
which are spread over 10-130 Mpa. A
Page 131 and 132:
CaMPO FOrMOSO, Brazil Sub level cav
Page 133 and 134:
Slot drilling at Ferbasa: The Simba
Page 135 and 136:
getting the best for Peñoles Speci
Page 137 and 138:
They went from drilling 20 m downwa
Page 139 and 140:
keeping a low profile at Panasqueir
Page 141 and 142:
Boomer S1 L drill rig in operation.
Page 143 and 144:
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