The Evolution of Block Caving Technology Tony Weston MAusIMM(CP) MassMin 2016

Transcription

1 The Evolution of Block Caving Technology Tony Weston MAusIMM(CP) MassMin 2016 : Turton, 1952, with permission from SME 1

2 Caving Methods Top slicing Sublevel caving Block caving Open stoping with mass blasting of pillars and draw under cave. Typical gravity block cave at Miami mine, Arizona, USA Hensley, 1973 with permission from SME 2

3 Block Caving 1 The term block caving is used in this presentation as a name for the mining method where a small portion of a block or orebody, the undercut, is drilled and blasted, and induces caving in the remainder of the block or orebody. It includes panel caving, as a subset and sequencing variant of block caving. Ray mine, Arizona, USA Blackner, 1915, with permission from SME 3

4 Block Caving 2 Block caving can be divided into various types according to the method for lateral transfer of the ore from the drawpoints to a crusher or haulage system: Early block caving a mixture of methods leading to gravity block caving. Gravity block caving transfer through a grizzly and inclined raises with some early examples using small scale rail haulage. Includes some hybrid methods. Scraper block caving scraper (slusher) winch and hoe. Load haul dump (LHD) block caving current technology using mainly diesel powered units. 4

5 Current Block Caving Practice Load haul dump (LHD) block caving: Undercut level Extraction level Haulage level Graphic Image: Atlas Copco, 2011 with permission from Atlas Copco 5

6 Top Slicing 1 Originated in England. Michigan, USA iron ore mines. Western USA copper mines. Slices of ore were mined using timbering in broken ground. After slice was mined timber was blasted down and caving induced. Horizontal top slicing Image: Jackson,1932, courtesy of SME 6

7 Top Slicing 2 Labour intensive. Large user of timber. (Lewis, 1941) Inclined top slicing at Coronado mine, Arizona, USA. Jackson,1932, courtesy SME 7

8 Early Block Caving 1 Pewabic mine, Michigan, USA, 1890s, mining hematite iron ore. Brinsmade,1911, public domain, courtesy of Hathi Trust 8

9 Pewabic mine, Michigan, USA, longitudinal section Early Block Caving 3 Stage 1 Stage 2 10

10 Pewabic mine, Michigan, USA Early Block Caving 4 Stage 3 Stage 4 11

11 Pewabic mine, Michigan, USA Early Block Caving 5 Stage 5 Stage 6 12

12 Pewabic mine, Michigan, USA Early Block Caving 6 Stage 7 Stage 8 13

13 Early Block Caving 7 Ohio Copper mine, Utah, USA Blocks 30 m square, with an initial height of 9 m, later increased to 18 m. Combined undercut and extraction level. Inclined ore passes, with approximately 150 per block. Undercut level developed, and drilled and blasted. Section showing representative ore passes at Ohio Copper mine. Schmidt, 1915, public domain, courtesy of Hathi Trust 14

14 Early Block Caving 9 Ohio Copper mine, Utah, USA Rises for ore passes developed to just below the undercut level. Last round in the rises broken through to the undercut after the undercut was blasted. Draw controlled at the grizzly on the level below. (Schmidt, 1915) Cross section of undercut drilling at Ohio Copper mine Schmidt, 1915, public domain, courtesy of Hathi Trust 15

15 Gravity Block Caving 1 Inspiration mine, Arizona, USA Copper mine on the same ore deposit as the Miami mine. Based on the mining method used at the Ohio Copper. Physical modelling of the design performed using large box and small rocks. Commenced production in 1915 Block 30 m square in plan. Inspiration mine, Arizona, USA undercut level plan Inspiration mine undercut level plan Stoddart, 1946, with permission from SME 16

16 Gravity Block Caving 2 Inspiration mine, Arizona, USA Separate undercut, grizzly and haulage levels. High labour and supply costs for underground mining after World War 2. Open pit mining commenced in 1948 in areas previously planned for block caving. (Parsons, 1933; Parsons, 1957; Stoddart, 1946; Weed, 1950) Inspiration mine cross-section, in lowest section of the orebody Stoddart, 1946, with permission from SME 17

17 Gravity Block Caving 3 El Teniente (previously Braden) mine, Chile: Production started in 1906 with glory holes from surface and then shrink stoping. Pillars between parallel shrink stopes undercut and drawn down under cave. Later adopted gravity block caving. LHD block caving commenced in early 1980s. (Webb and Skinner, 1932; Ovalle and Albornoz, 1981; Turton, 1952) El Teniente mine, pillar undercutting Image: Webb and Skinner, 1932, courtesy of SME 18

18 Gravity Block Caving 4 El Teniente, drawing ore at a grizzly level, circa 1952 Turton, 1952, with permission of SME El Teniente, ore haulage, circa 1952 Turton, 1952, with permission of SME 19

19 Gravity Block Caving 5 Miami mine, Arizona USA Production commenced in A variety of mining methods used prior to block caving. Square set stoping Top slicing. Shrink stoping with sublevel caving of pillars. Miami mine, shrink stopes and pillar sublevel caving Hardwick 1965, courtesy of SME 20

20 Gravity Block Caving 6 Miami mine, Arizona USA Transition to block caving (with transfer levels in place of grizzlies). Block caving of the whole orebody performed but unsuccessful. Block caving of panels 45 m wide across the orebody with two intermediate transfer levels. Miami mine, block caving a 45 m panel across the orebody Hardwick,1965, courtesy of SME 21

21 Gravity Block Caving 7 Miami mine, Arizona USA Gravity block cave 45 m by 90 m in plan with a height of 90 m or more. Flat draw over the area of the block. Includes boundary weakening. Blocks later reduced to 45 m square in plan. Limited use of scraper block caving. Block caving was suspended in (Hardwick, 1965 ; Hensley, 1973) Miami mine, 45 m by 90 m block Hensley, 1973 with permission from SME 22

22 Scraper Block Caving 1 Climax mine, Colorado, USA, scraper block caving: A molybdenum mine. More competent orebody resulted in larger fragments, more hangups and secondary breaking in gravity block caves. A scraper (slusher) winch pulled a large hoe to load rail wagons. The scraper block caving system was used from the mid 1930s to replace gravity block caving. (Julin et al, 1973: Henderson, 1944; Bucky, 1945) Graphic Climax mine scraper block caving layout Julin et al, 1973, with permission from SME 23

23 Scraper Block Caving 2 Graphic Climax mine scraper winch Henderson, 1944, with permission from SME Climax mine scraper drive Henderson, 1944, with permission from SME 24

24 LHD Block Caving 1 Henderson mine, Colorado, USA: Henderson is a molybdenum mine which commenced production in LHD block cave with continuous panel caving designed as such from its inception. Drawpoint configuration was initially an offset herringbone shown in the drawing but later changed to a Z shape. Henderson mine initial drawpoint configuration Doepken, 1982, with permission from SME 25

25 LHD Block Caving 2 Henderson mine, Colorado, USA: The drawbells were initially designed with a vertical slot and rings blasting from either side. Later changed to a layout without a vertical slot and with all the blastholes drilled from the undercut level. Henderson mine drawbell and undercut blasthole drilling layouts Doepken, 1982, with permission from SME 26

26 Conclusions Older mining methods such as top slicing and shrink stoping were important precursors to block caving. Hybrid methods provided a springboard for the adoption of block caving. The separation of the undercutting, draw and haulage unit operations was important in the success of early block caving. The detailed design of block caves depended on local conditions, and previous mining practice. Increasing depth and ore competence drove changes in the block caving method. 27

27 Acknowledgements The assistance of the Society for Mining, Metallurgy and Exploration (SME) in providing drawings and photographs for this presentation and paper is gratefully acknowledged. Ray mine, Arizona, haulage drive showing chutes and heavy timbering. Blackner, 1915, with permission of SME 28

28 Questions? 29

29 References 1 Atlas Copco, 2011, Mining methods in underground mining, Atlas Copco Rock Drills AB, CD format, k Blackner, L A, Underground mining systems of Ray Consolidated Copper Co, in Transactions of the American Institute of Mining Engineers, pp (American Institute of Mining Engineers: New York). Brinsmade, R B, Mining Without Timber, pp (McGraw- Hill: New York). Brown, E F, System of mining ore bodies of uniform grade, in Proceedings Lake Superior Mining Institute, Vol 5, pp (Lake Superior Mining Institute: Ishpeming). Doepken, W G, 1982, The Henderson mine, in Underground mining methods handbook, (Hustrulid ed), 1982, pp (Society for Mining, Metallurgy, and Exploration, Littleton, Colorado). Henderson, R, 1944, A comparison between the chute and grizzly system and the slusher system at the Climax mine, Transactions, pp ( American Institute of Mining, Metallurgical, and Petroleum Engineers, New York). Hensley, J H, Mining methods of the Miami Copper Co, Trans Am Inst Min and Met Eng, 72:78 99 (American Institute of Mining Engineers: New York). Hensley, J H, Young, G W and McLennan, F W, updated by Fletcher, J B, Miami Copper, Arizona, in SME Mining Engineering Handbook, first edition, vol 1, pp to (The Society for Mining, Metallurgy, and Exploration Inc: New York). Jackson, C F, 1931, Mining by the top-slicing method, with some notes on sublevel caving, Information Circular IC 6410 (United States Bureau of Mines: Washington DC). Julin, D E and Tobin, R L, Block caving, in SME Mining Engineering Handbook, first edition, vol 1, pp to (Society of Mining Engineers of The American Institute of Mining, Metallurgical, and Petroleum Engineers Inc: New York). Julin, D E, Smith, A K, Ohmert, E L and other Climax staff, Climax caving system, in SME Mining Engineering Handbook, first edition, vol 1, pp to (Society of Mining Engineers of The American Institute of Mining, Metallurgical, and Petroleum Engineers Inc: New York). Lehman, Ore drawing tests and the resulting method of Inspiration Consolidated Copper Co, Trans Am Inst Min and Met Eng, Sep, pp (American Institute of Mining Engineers: New York). Lewis, R S, Elements of Mining, second edition, pp (Wiley: New York). 30

30 References 2 MacLennan, F W, Miami Copper Company Method of Mining Low-grade Orebody, Technical Publication No 314, 44 pp (The American Institute of Mining and Metallurgical Engineers: New York). Ovalle, A W and Albornoz, H R, Block-caving with LHD equipment at El Teniente, in Design and Operation of Caving and Sublevel Stoping Mines, pp (Society for Mining, Metallurgy, and Exploration Inc: New York) Parsons, A B, Who produced the world s copper in 1925?, Engineering and Mining Journal-Press, 22 May, pp (McGraw-Hill: New York). Parsons, A B, The Porphyry Coppers (American Institute of Mining and Metallurgical Engineers: New York). Parsons, A B, The Porphyry Coppers in 1956, (American Institute of Mining, Metallurgical and Petroleum Engineers: New York). Peele, R, Mining Engineers Handbook, vol 1, pp (Wiley: New York). Schmidt, F S, Caving system at the Ohio Copper mine, Mining and Scientific Press, vol 110, March 6, pp Stoddard, A C, History and development of block caving at the mines of the Inspiration Consolidated Copper Company, AIME Transactions, pp (American Institute of Mining Engineers: New York) Turton, F E, 1952, Mining operations at the Teniente mine of the Braden Copper Company, Rancagua, Chile, Mining Engineering, June, pp , American Institute of Mining Engineers: New York). Vink, D M, From green field site to block cave mine results of Northparke s drill and blast design process, in Proceedings Seventh Underground Operators Conference, pp (The Australasian Institute of Mining and Metallurgy: Melbourne) Webb, J S and Skinner, T W, Mining methods and costs at the Braden Copper Co s mines, Sewell, Chile, Information Circular IC 6565 (United States Bureau of Mines: Washington DC). Wightman, R H, A new caving procedure at the Crestmore limestone mine, AIME Transactions, pp (AIME: New York). 31