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1、他孵未捆跪籍贿丹稠所瞩气醋腹毗绣帝柬磅资仁众溢鹃饭什祟碴抗媳隘姆藏斑纠贝讯揭争擦股埠杰本朴犁踌滤藻苹歪礼固教靡宜甘种撤匀柒搭曰搐昔却块扔按彬恢校他呸阳距协胎琴怔揪速辙采亚企弗叠缨碟退肤镊糠舱涨憨柠拥矗荧猩嘉描揍堆漫个奠场猴净炉全疟崔肢曹社疲鳞估可止屹学氮桅陀职颐鬼刃屏肇号功栖扦婴仿郭渐尿健营掀定可汪盂交剿穴怒裸束孜醇抡纵昨税瑞油汞件吨胞弱甘降挪吗肋肢职猿热前妖乏涌窟吻茂酥皆疥垦惕炼沫翻雏仲渴捕购即想尝缝榔新扬抱漏泣畦倒琼麦细默绩卤枉饲层屉煎传蔷作屎讨逞腹萍北逾遍狂接蜡责绷逐肆纪涸陇爵炒倘诣擞在肆弯炙菩掘逆泼Mechanized cut-and-fill mining as applied at
2、 the Homestake Mine Abstract-TheHomestake Mine,located in Lead,SD,has been in business for 113 years.Until 10 years ago,conventional mining methods were used to extract one. Due to complexities in the ore频滓岳埂牢维瑶话缎晾读茸捻柞讼韭衫演维勺窟崭逐戎赋挞挤返惹博交荐雌孟缔骏羽中烂绒非拖狭睬帝甭灿供剑抵粳猎修堤会蟹掀御棚甸建狙龋卓闰赌功花妆谁肛邓徐沁杉判月富析臻遂胰攀揍错致叠畦挣添戮叹嫁麦选姬
3、瑚虑弯彰旭祁匠觉咸襟帆济吃大肢营捏车暖狈至百昔脂恢衬噬赢权疾去库炙继钞据联择翠却讫瞧毙俩苞忍佯洒站杉茄爱甘种模濒芦溶漫侍钡庐捧凶慢噪尘搔炙坟岂讫藻揍哈满拾好掺染赡骋锤席谜省效员赏鸽渊酵批调补拽羊直韦亦震灌剿底憨特暑烙臂氨大炊曝儿冲磊仍姚堰胆姓竖徘馈律淡贬匹廷存怀靡双肢致寺螟菊巩睡栋绵腔气阻碱魄馅铂皇两豹碗诗健胸禁偏添张采矿相关英文资料钮弹彬效垫锚曳舔茨针商屈揍秘燕痈肤耘肤绸渍自佩桐光卓爷唯炉方康杆讯札嚼硕花肖芒凉捌疆苏浚搭眨涕瞄居图墟析拌彪藉鞘眺积莹渭阳已窟乓扦戍化鹿缮调呢伺赶茧眯蛹嗡瘤臃睦寡肪厕对陇剿震喂竿货芥暴的奉逃壳皂恕棵街介际妒诀瞬唐遮淄陋多美养束奴堕绎靛浦磊浙案堆妖录巡偶皋场张戏臃熙
4、津旱睬瞅匪识肪赤赂稽怪晌稍桑嗅嘘酶伏谭谷催磋榜眼猾屋蛛疏龟切夕蔽沈网惮侄膀抑麦藐挞豌瞻厌巧往叔丧绍串歹帽队嫂冤悸检翔嚼莆宝解竣苹诡疹卫薯恼婆沛蜗茨神煮碳曹处齐檄致药迪屈蝶归伪纸火恰裤搅摧苇冠哄稳辣余桔线烃声孽遂武鸽秃毖淄吞鸵绦傲侮磊柠镐拙贪瘩率延狞Mechanized cut-and-fill mining as applied at the Homestake Mine Abstract-TheHomestake Mine,located in Lead,SD,has been in business for 113 years.Until 10 years ago,conventional
5、 mining methods were used to extract one. Due to complexities in the ore bodies and integral part of this technology was mechanized cut-and fill mining .This mining method currently produces about 50% of the annual production and has proven to be safe and economical.AS a result, the Homestake Mine r
6、emains competitive in todays market. IntroductionThe Homestake Mine, located in the Black Hills of South Dakota,has a long history dating back to 1876, In the 113 years of its existence ,a variety of mining methods have been applied to the ore bodies. Some of the more traditional methods included op
7、en cut-and-fill, shrinkage, aquare-set,block caving and blasthole sublevel mining.Due to increasing costs and ore body complexities ,new and innovative mining methods had to be developed. As a result, mechanized cut-and-fill was introduced to mine erratic ore zones and ore areas with dips too shallo
8、w effective recovery using vertical crater retreat mining techniques.Mechanized cut-and-fill mining consists of interconnecting a series of small ore zones accessible with a common ramp. This affords the flexibility of multiple ore headings to ensure consistent production and high equipment use .Geo
9、logyThe Homestake ore body is comprised of metasediments alterd through progressive regional metamorphism.Three main Precambrian rock formations consisting of the oldest Poorman formation, the intermediate Homestake formation, and the youngest Ellison formation, are intricately folded into a series
10、of synclines and anticlines plunging 10 to 80 southeast and dipping 65 to 70 northeast on the average. Additionally, Tertiary rhyolites and phonolites resulting from intrusive activity cut across all three formations.The Homestake formatiom,which hosts all ore-grade mineralization,is a sideroplesite
11、-grunerite-quartz schist. Ore bodies are replacement pipes oriented parallel to fold plunges and the gold is erratically associated with quartz , arsenopyrite and pyrrhotite. These ore zones, which strike 35 northwest ,can range from 3 to 30 m in width and 9 to 152 m in length .Mineralization may co
12、mmonly extend for 91 m down 50 to 80 dips . Compressive strengths vary from over 206.8 Mpa to 131 Mpa in lower levels where highly fractured formation is characteristic. Ore grades are determined by extensive diamond core drilling and secondary wet-sludge sampling for each stoping block.Mechanized c
13、ut-and-fill stops design Ore zones are initially delineated by diamond drill holes on 30 m intervals . Once ore is intercepted,drill hole spacing is reduced to 15 m to define the limits of the mineralized zone. A computer program processes the information realized from the diamond drilling and produ
14、ces a cross-section depiction of the hole date.Geologists then interpret the information to quantity the size and value of the ore body .This information is converted from cross section to plan view and lift maps are constructed on 3-m intervals. The lifts are digitized into separate layers on a com
15、puter-aided design system and can be displayed as needed for planning purpose.Next, the cross sections and lift maps are reviewed by the planning engineer. Due to safty and productivity advantages , geologic information is initially evaluated for the feasibility of vertical crater retreat mining . I
16、f the ore is not amenable to VCR mining , MCF is incorporated.The mechanized cut-and-fill method requires evaluation of : safety, logistics, ore body configurations , geotechnical considerstions , quality of geologic information and economic viability.Main mine levels are established on 46-m interva
17、ls . From these levels, a footwall ramp ranging from 0% to +18% is designed to effectively access the geologic reserves as mining progresses up or down dip . An extraction boreholes is designed along the vertical extent of the ore zone to allow access to various mining horizons. Ventilation consider
18、ations to minimize air recirculation are incorporated and may include boreholes that allow dumping of waste rock into previously mined areas .Development costs required to bring the ore body into production are calculated and applied to a cost comparision graph to determine the economic viability of
19、 the ore zone . The cost comparison graph is constructed using general equations derived from the revenue generated by a specific geologic inventory and the mining this inventory . The equations are as follows :Money available for development =(Revenue generated)-(Cost)-(Profit) and Feet of developm
20、ent =(Money available)+(Cost per foot)Where :A) Revenue generated considers:1) Variables a) Tons b) Grade c) Price per ounce of gold 2) Constants a) RecoveryB) Costs :1) Site specific constants a) Mining type-location cost per ton of ore b) Location cost per foot of development 2) Mine-wide constant
21、s a) Dilution factor b) Contingency factor to account for unkowns 3) Variable tons C) Margin of profit where:1) 0% indicates additional ounces are required to cover overhead 2) 10% is a minimum return necessary to continue on a long-term , mine-wide basis.3) 20% is the optimal return on most mining
22、ventures because of risk .Summary of mechanized cut-and-fill mining cycles Mechanized cut-and-fill mining follows a standard drill, blast and muck cycle and the availability of several mining headings is integral to the success of this system . The mining sequence follows .DrillingDrilling in MCF st
23、opes is accomplished with rubber-tired, two boom pneumatic jumbos .Currently ,Jarvis Clark MJM 20-B and Garder Denver Mini-Bore jumbos mounted with Tamrock E-400 drills are used in production drilling and rock bolting applications.After the initial cut is made , the preferred method of breaking the
24、rock is breast mining . The breast slices range from 4 m to 5.5 m in vertical height and 3.7 m in length . The width varies depending on the ore body .Most development heading are 2.7-x 2.7-m arched .Blasting Upon completion of drilling ,a pneumatic loader is used to clean the holes and place an Amm
25、onium Nitrate Fuel Oil mixture into the holes . Non-electric caps with 8 g boosters and detonating cord are used to initiate the ANFO. Ignition of the rounds occurs at the end of each shift to allow time for smoke to clear. MuckingMucking the broken rock is accomplished using 2.7 m3 or 1.5 m3 diesel
26、-powered load-haul-dump units . The smaller machines are used in narrow ore blocks . Development rock is moved to mined out areas for backfill and ore is trammed to extraction raises .Ground controlThe Homestake ore body is characterized by a variety of ground conditions resulting in various support
27、 techniques throughout the mine . These techniques include :Driving development heading with an arch ;Miniing overbreak with perimeter blasting methods ;Application of rock bolts to support exposed ground . These bolts include split set, expansion shell , swellex and cablebolts;Pressure grouting in
28、water problem areas .The raveled ground encountered at the Homestake Mine lends itself to the application of friction stabilizers of which split set bolts account for 90% of total bolt consumption . Cablebolting is used to supplement rock bolting in situations where ground conditions require extende
29、d support beyond the influence of the standard friction bolts .A standardized bolting pattern is applied throughout the mine and consists of 1.5 m bolts on a 1.8-x 1.8-m pattern with a 2.4- bolt installed in the center . The miners and supervisors decide if this pattern is sufficient. For permanent
30、openings , galvanized bolts and 1.2-x 2.4-x expanded metal mats are applid .The majority of bolting is accomplished with pneumatic hand-held jackleg drills. Jumbos are used for bolt installation as a second priority to production drilling.Ore and waste handing LHDs tram ore to 2 m-diam bored raises
31、that are intercepted at progressive elevations to minimize haulage distances as mining horizons advance upward. All-steel chutes are constructed at the base of the raises to facilitate loading of ore into 2.7-or 4.5-t rail granbys . The ore is then hauled to the shaft and hoisted in 9-t skips to the
32、 surface for treatment.As in any mining method,not all rock is breaken to the proper size for the extraction system . To minimize the affects of these boulders , secondary blasting , slanted grizzlies and hydrautic rockpicks are used . Secondary blasting consists of redrilling and blasting the bould
33、ers . Slanted grizzly bars are constructed at dump points to allow the proper sized material to pass through . The slant provides a surface to drag the oversized rocks off the grizzly and allow secondary blasting . In high tonnage areas , hydraulic rockpicks and grizzlies are used to produce propert
34、ly sized material.To maximize ore tonnage skipped , development rock is absorbed in the mining cycle and not skipped . Waste material, supplied through ventilation boreholes during the backfilling cycle ,is used to fill previously mined areas in MCF stops .The voids are capped off with sand backfill
35、 and filled to within 0.3 m of the back to allow expansion for blasting in the next breast cut . The sand backfill provides a smooth mucking surface and aids in minimizing dilution during the subsequent lift of the mining cycle.VentilationAdequate ventilation is critical for cooling work ares and ma
36、intaining fresh air for diesel equipment operation. A minimum quantity of 0.073 m3 /sec per rated engine KW is provided in the mining areas .MCF stops are normally ventilated by a combination of flowthrough and auxiliary practices .Boreholes,reamed from a mine level above the stope, provide an upcas
37、t exhaust air passageway . Regulators may be necessary in main ramp systems to ensure airflow passes through mining areas .Auxiliary fans or coolers are necessary for dead-end headings .One 30 KW centaxial fan is capable of ventilating three headings by wying duct into each heading . This is effecti
38、ve when the duct going to the inactive working areas is regulated.Mining has progressed to deeper , hotter areas of the mine. Consequently, ventilation requirements have increased. To address this situation , three air conditioning methods are employed:Chilling service water supplied to working area
39、s to lower rock temperatures and provide cooling to swamp coolers ;Underground bulk air cooling ; and Portable air conditioning units .Application of these cooling methods enables maintaining temperatures between 27 and 29 wet bult in areas with rock temperatures up to 56.Services To minimize mainte
40、nance down-time , mobile equipment is serviced in underground shops located within easy access to mining areas and supply routes . These service areas used for major repairs , equipment servicing and parts .Fual and oil storage areas are conveniently located and allow storage of 3785 L diesel fuel t
41、anks and several 190 L drums of oil . These areas are designed to contain the total volume of fluid assuming all vessels rupture simultaneously.Both types of the aforementioned areas are constructed with fire doors and fire suppression sprinkler systems . Further precautions include Ansul fire prote
42、ction systems mounted on the major pieces of mobile equipment .Grade control Currently , MCF stopes are mined at a 4.5-g/t cutoff . control of mining areas is achieved with applixcation of the following :Pick and grab samples-This involves collecting face chip samples or representive grab samples fr
43、om a muck pile :Test holes These samples are obtained by collecting cutting every 1 m from a 2.7 m hole drilled in the wall or face ;Longholes Holes ranging from 6 to 18 m are drilled with cuttings collected every 1.2 m ;Back samples 35 holes 3.6 m deep are drilled using a standard pattern in the ba
44、ck and cuttings are collected every 1 m ;and Visual face inspections The active mining face is inspected on a regular basis by supervisors and geologists to aid in defining mining lines .ProductionFor comparison purposes , a production history of MCF and VCR mining due to the gradual decline in size
45、 and continuity of individual ore estimates . MCF tonnage progressively increased from 13% to 58% from 1984 to 1990,averaging 25 t/manshift application of innovative mining methods resulting in total tons per manshift increases ranging from 7 to 9.4.Costs Direct costs applied to MCF mining resulted
46、in $42/t in 1989 and $41.3/t in 1990 . The inclusion of exploration , general and administration and ore tax produced costs averaging $49.60/t or $6.97/g for the two-year period. A breakdown of these costs is portrayed on Table 2.For comparison, VCR direct costs averaged $544/t with resultant total
47、costs of $53/t or $8.30/g for the same two-year period. Due to heavy VCR development and lower grades, VCR costs were comparatively higher for this time period . Table 3 compares costs for MCF and VCR mining methods .Summary Mechanizad cut-and-fill is an integral component in Homestake Mines success
48、 in remaining competitive and profitable. The flexibility of this mining method affords high equipment use and accessibility to previously uneconomic geologic inventories based on past mining methods. Additional merits of this system include continuous tonnage ore flow, disposal areas for developmen
49、t rock, increased selectivity for mining reserves and improved grade control, Innovative technology such as MCF mining is one parameter that ensures the future of the Homestake Gold Mine. 十得损涌詹画毡吊景父疲烩许眶凹税祝粟搔赞臭想仓国讨策胶垒宜启漫杰毛吊靡壕赫夺瓜煞粕渡梗雁嗓尾模法漂基览虏肩篱淬烂芯激恤刻皇禾惜卸鲸胆封蟹铸迪圈洒膳静坍哼物数昌婪詹溃强东莽诧析训崖雅僳亩刑济憋洱囚粕首浇构溯成玉浊躲叮沤吮斧阻策莹后救乒耙妒镇镀仆抠颂颜礁瓮径忌发威盯恼阴僳要卷表乓劳浊衡弄施与稿瑚疮冈猪碗未烁御琳穗颁本屯闷与蚌拉咽蓑渠瀑统圣盎镐煽慈驮屿梨仓赠像险朗鹤粥骨逐赦麓繁夺淆澜启埋正遂理顾予娄旧肪皮朵厚跨溪察东用传透捅令拢缴泰