US3848927A

US3848927A - Mining method using control blasting

Info

Publication number: US3848927A
Authority: US
Inventors: C Livingston
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-02-25
Filing date: 1971-08-18
Publication date: 1974-11-19
Anticipated expiration: 1991-11-19

Abstract

A mining method comprising: A. PREPARING A BENCH FREE FACE BY CONDUCTING TEST BLASTS; B. ESTABLISHING A PATTERN OF CELLULAR UNITS SEPARATED BY PILLARS OF THE ORE BODY TO BE MINED; C. TUNNELING HORIZONTALLY THROUGH THE ORE BODY PERPENDICULAR TO THE FREE FACE IN THE PILLAR AREAS; D. TUNNELING THROUGH THE CELLULAR UNITS PARALLEL TO THE FREE FACE AND AT THE SAME LEVEL AS THE TUNNELING IN STEP (C); E. PLACING CHARGES IN THE TUNNELS FORMED IN STEP (D) IN THE AREA OF THE CELLULAR UNITS; AND F. DETONATING THE CHARGES. The concept of product control blasting, trajectory control blasting and/or stability control blasting are applicable to the mining method.

Description

i Hamil 0R St de/E3992"? i United States Patent Livingston MINING METHOD usING CONTROL BLASTING [76] Inventor: Clifton W. Livingston, 624

- Panorama Dr., Grand Junction,

Colo. 8150] [22] Filed: Aug. 18, 1971 [21] Appl. No.: 172,736

Related U.S. Application Data [62] Division of Ser. No. 14,166, Feb. 25, 1970.

[52] U.S. Cl...; 299/13, 299/18 [51] Int. Cl. E2lc 37/00 [58] Field of Search 299/2, ll, l3, 18, 19

[56] References Cited UNITED STATES PATENTS 3,301,599 1/1967 Heimaster 299/18 3,588,175 6/1971 Whiting 299/19 OTHER PUBLICATIONS L C. Lang, Mining Itabirite on the Bong Range In Liberia, reprint, Canadian Mining Journal, Nov., 1965.

L. C. Lang, Pit Slope Control by Controlled Blasting,

HIGH TERRACE TERRACE INTERMEDIATE TERRACE OPEN CELL WATER STORAGE RAM HIG INTERMEDIATE Nov. 19, 1974 Reprint, Canadian Mining Journal, Dec., 1965.

Primary ExaminerErnest R. Purser Attorney, Agent, or Firm-Sherman & Shalloway [57] ABSTRACT A mining method comprising:

a. preparing a bench free face by conducting test blasts;

b. establishing a pattern of cellular units separated by pillars of the ore body to be mined; c. tunneling horizontally through the ore body perpendicular to the free face in the pillar areas;

d. tunneling through the cellular units parallel to the free face and at the same level as the tunneling in step (c);

e. placing charges in the tunnels formed in step (d) in the area of the cellular units; and

f. detonating the charges.

The concept of product control blasting, trajectory control blasting and/or stability control blasting are applicable to the mining method.

30 Claims, 36 Drawing Figures HIGHWALL ACTIVE MINING CELLS TERRACE PArEmmnvlslsm 3,848,927

sum mar CRATER PATENIE HUV I 91974 saw an or 21 PATENH" 9 '9 3, 848.927

sum 05 or 21 LBS. 04, 1958 NOW SURFACE 10 LBS. c- 4, ICE I 0.8

10 I. as. A 60 TR ENCH SNOW I 02 CHURCHILL TILL 0.4

///' ATLA$ 6C, KEWEENAW SILT ENERGY UTILIZATION NUMBER, A

DEPTH RATIO A PATENIEL I 91974 3. 848.927

SHEET as or 21 'SCALED CHARGE DEPTH AB w- I I I /l 8 I I I I I 8 l I I I. I I I I I 7 I I I II 7 I I RADIAL I I CRACKS I l I 6 l I s I I l secono RING I I I ICRACKS I I I J! I l 5 I I I I 5 Io -INCREMENT I I fl QI I Lu i I LZ) I B 4 I CRATER I I 4 5; I QIMIT I I I Q B I '2 I C I I j I I I 3 y I I 3 o l I w I I .I g FRAGMENTATION RANGE. DOMING RANGE l 2 I I I 1 I 1 2 AB. 9 I S.R.' PR. I SH. UPLIFT REGION I J REG.,' i R. F I I I 1/ I l I AIRBLAST |e.s.o. w R. on. PRE-CONDITIONING I i I I I P S I 4 I I 4 I 3 I I j: 3 2 v I V I 2 AU B I V I X I l I I \l N I l O 1.1 17 v 0 O RAT ERING SCALED BURDEN d I I I 90 o I I 4 I W 0 I 2 3 4 5 I 6 LEGEND:

A.B. REG. Airblasi Region 8.8.0. Bond SIrengIh DesIrucIion SR. Secondary Region V/W R. V/W Region P. R. Primary Region C.R. Course Region SH.R. Shear Region AU. B Auiogenous Blasting P.SI ParIicle Size 0.8. Conventional Blasiing PATENIELHUV 1 9 14 3; 848.927 1 SHEET 09 UF 2! w; I 0 m Lataraloxtant of bond g y I/ strength dutruction '5 (gas bubble rodiuu) I 8 0.4- g z' .7 0 i 7 1 N SCALED CHARGE DEPTH l l o l I DEPTH RATIO A PATENTEL my 1 sum SHEET 10 0F 21 DIRECTION OF ADVANCE ORIENT PAFIALLEL t0 MAJOR JOINT SYSTEM END LINE A (PRIMACORD LOOP BURDEN CONTROL LINE B FACE DO NOT REDUCE MINIMUM l, SLIDING RESISTANCE REPLACE LINED WITH LINE C, ADD LINES B AND A ON OPENING SHOT PRIMACORD LOOP SHORT PERIOD BACK LINE E DELAY NO.

CODE V-1 V-Z V-3 B-1 8-2 8-3 8-4 8-5 8-6 8-7 8-8, sYM Q Q (h 69 6 0 I82 E Q DIA. IN. 9.875 9.875 9.875 9.875 9.875 9.875 9.875 9.875 9.875 6.525 5.625

SUB. FT 6.91 6.17 6.27 I 6.17 5.78 5.47 4.97 4.97 5.18 4.50 3.70 DEPTH ft. 40.91 40.17 40.27 40.17 39.78 39.74 38.97 38.97 39.18 38.50 37.70

LINE OF SYMMETRY D FOR COMPOSITE BLASTS PATENI rznv 1 91924

sum

13 or 1 PATENTEL HEY I 91974

snm

15 or 21 4 3 .Ewummm PREDOMINANT PARTICLE VOLUME, CU FT PATENTE HS! 1 91974 sum 18 or 21

Claims

1. A mining method comprising: a. preparing a bench free face by conducting test blasts; b. establishing a pattern of cellular units separated by pillars of the ore body to be mined; c. tunneling horizontally though said ore body perpendicular to said free face in said pillar areas; d. tunneling through said cellular units parallel to said free face and at the same level as said tunneling in step (c); e. placing charges in the tunnels formed in step (d) in the area of said cellular units; and f. detonating said charges.

2. The method of claim 1, wherein overburden is removed from the ore body by trajectory control blasting.

3. The method of claim 2, wherein the trajectory control blasting is conducted by controlling the trajectory of material formed as bench geometry surrounding a blast charge in response to explosion of the charge by: i. placing a charge of weight W at a vertical depth Delta v wherein Delta v dv/N wherein dv is the vertical depth, N being the depth of placement of a charge of given weight which first begins to produce upon explosion of the charge fractures on the surface of the material in which the charge is placed; ii. positioning said charge of weight W along a rearward extension of a line perpendicular to the bench free face at a burden Delta b wherein Delta b db/N wherein db is the burden distance and Delta b Delta v + Delta diff wherein Delta diff is a predetermined positive value, the trajectory being substantially in a vertical direction when Delta v is less than Delta b and substantially in the horizontal face direction when Delta b is less than Delta v; and iii. detonating the charge.

4. The method of claim 2, wherein the overburden positioned above an unmined cellular unit is projected to the area defined by previously mined cellular units by trajectory control blasting.

5. The method of claim 4, including building terrace ponds over the filled cellular units, said ponds including dykes.

6. The method of claim 4, wherein the trajectory control blasting is conducted by controlling the trajectory of Material formed as bench geometry surrounding a blast charge in response to explosion of the charge by: i. placing a charge of weight W at a vertical depth Delta v wherein Delta v dv/N wherein dv is the vertical depth, N being the depth of placement of a charge of given weight which first begins to produce upon explosion of the charge fractures on the surface of the material in which the charge is placed; ii. positioning said charge of weight W along a rearward extension of a line perpendicular to the bench free face at a burden Delta b wherein Delta b db/N wherein db is the burden distance and Delta b Delta v + Delta diff wherein Delta diff is a predetermined positive value, the trajectory being substantially in a vertical direction when Delta v is less than Delta b and substantially in the horizontal face direction when Delta b is less than Delta v; and iii. detonating the charge.

7. The method of claim 1, wherein said tunnels communicate between said cellular units to permit drainage control, and the mining method further includes the step of providing valve means in said tunnels.

8. The method of claim 1 further including establishing a plant pillar and constructing an ore processing plant thereon, within the confines of the mine field.

9. The method of claim 1, wherein at least one cell is maintained free of any earthen material.

10. A mining method including: a. clearing overburden from an extended area of underlying ore by trajectory control blasting; b. excavating in a stepped fashion a grid of cellular units in the exposed ore body, said units being separated by barrier pillars; and c. forming ramps in the pillars as mining progresses downwardly for access to the ore.

11. The method of claim 10 further including progressively filling the mined-out cellular units with overburden and mill tailings.

12. The method of claim 11, further including placing water quality filter beds on the floor surface of said cellular units prior to filling with overburden and tailings.

13. The method of claim 10, wherein said excavating is performed by product control blasting.

14. The method of claim 13, wherein the product control blasting is conducted by: i. conducting test crater blasts at various depths to determine the breakage limits of the material in response to the blasts; ii. preparing a chart by plotting the slant distance to each of the types of fractures in the blasting failure process and to the doming limit from test crater blasts; iii. establishing a grid over the crater formed by each test blast and measuring the particle size of the broken material touched by the grid; iv. preparing a chart by plotting the variation of the predominant particle size with various charge depths at scaled depth ratios Delta ; v. determining in the range Delta d to Delta o from the chart of (iv) the value in the controlling burden direction at which the desired predominant particle size can be achieved, Delta d is the Delta value at which doming begins and Delta o is the value of do/N for the given charge weight, do being the depth of placement of a charge of the given weight which produces upon explosion of the charge maximum pressure rise within the material, and N being the depth of placement of a charge of the given weight which first begins to produce upon explosion of the charge fractures on the surface of the material in which the charge is placed; or in the range Delta o to Delta equals 0 the value at which the desired particle size can be achieved where predominant particle size from autogenous blasting ranges from near zero to that measured at Delta o of the crater tests; vi. decreasing the crater chart value (v) by subtracting for bench geometry a Delta increment adjustment ranging linearly from a maximum at Delta bo- Delta o for a controlling burden of magnitude Delta o to zero for a controlling burden Delta a or less or for a controlling burden Delta ss or greater, increment being Delta bo minus Delta o, Delta bo being the value of dbo/N for the given charge weight, dbo being the perpendicular distance from the vertical free face to the center of gravity of explosive charge which produces upon explosion of said charge maximum pressure rise within the material, Delta a is the Delta value at which the volume of the apparent crater is maximum, and Delta ss being the Delta value at which cratering begins; vii. placing the charge at a distance from the controlling burden toward the face of the bench corresponding to the adjusted Delta value; viii. placing the charge at a distance from the non-controlling free face at the crater test determined value; and ix. detonating the charge.

15. The method of claim 10 further including drilling drain holes through said barrier pillars to provide water control tunnels communication between said cellular units.

16. The method of claim 10 wherein the trajectory control blasting is conducted by controlling the trajectory of material formed as bench geometry surrounding a blast charge in responsive to explosion of the charge by: i. placing a charge of weight W at a vertical depth Delta v wherein Delta v dvN wherein dv is the vertical depth, N being the depth of placement of a charge of given weight which first begins to produce upon explosion of the charge fractures on the surface of the material in which the charge is placed; ii. positioning said charge of weight W along a rearward extension of a line perpendicular to the bench free face at a burden Delta b wherein Delta b db/N wherein db is the burden distance and Delta b Delta v + Delta diff wherein Delta diff is a predetermined positive value, the trajectory being substantially in a vertical direction when Delta v is less than Delta b and substantially in the horizontal face direction when Delta b is less than Delta v; and iii. detonating the charge.

17. A mining method including: a. removing overburden from an ore body by trajectory control blasting; b. establishing a cellular grid structure including planned ore body cells separated by barrier pillars perpendicular to entry pillars; c. driving entries in the ore body perpendicular to the free face in said entry pillars; d. driving cross-entries from said entries through said planned ore body cells perpendicular to said entries and at the same ore body level; e. placing explosive charges in said cross-entries within the area defined by said planned ore body cells; and f. detonating said explosive charges.

18. The method of claim 17, further including the step of progressively and continuously performing steps (a) - (f) with the overburden being blasted by trajectory control blasting from its in situ position to its final resting place within a previously mined-out cellular unit.

19. The method of claim 17, wherein the trajectory control blasting is conducted by controlling the trajectory of material formed as bench geometry surrounding a blast charge in response to explosion of the charge by: i. placing a charge of weight W at a vertical depth Delta v wherein Delta v dv/N wherein dv is the vertical depth, N being the depth of placement of a charge of given weight which first begins to produce upon explosion of the charge fractures on the surface of the material in which the charge is placed; ii. positioning said charge of weight W along a rearward extension of a line perpendicular to the bench free face at a burden b whereiN b db/N wherein db is the burden distance and Delta b Delta v + Delta diff wherein Delta diff is a predetermined positive value, the trajectory being substantially in a vertical direction when Delta v is less than Delta b and substantially in the horizontal face direction when Delta b is less than Delta v; and iii. detonating the charge.

20. The method of claim 17, wherein steps (e) and (f) are carried out by conducting product control blasting by: i. conducting test crater blasts at various depths to determine the breakage limits of the material in response to the blasts; ii. preparing a chart by plotting the slant distance to each of the types of fractures in the blasting failure process and to the doming limit from test crater blasts; iii. establishing a grid over the crater formed by each test blast and measuring the particle size of the broken material touched by the grid; iv. preparing a chart by plotting the variation of the predominant particle size with various charge depths at scaled depth ratios Delta ; v. determining in the range Delta d to Delta o from the chart of (iv) the value in the controlling burden direction at which the desired predominant particle size can be achieved, Delta d is the Delta value at which doming begins and Delta o is the value of do/N for the given charge weight, do being the depth of placement of a charge of the given weight which produces upon explosion of the charge maximum pressure rise within the material, and N being the depth of placement of a charge of the given weight which first begins to produce upon explosion of the charge fractures on the surface of the material in which the charge is placed; or in the range Delta o to Delta equals 0 the value at which the desired particle size can be achieved where predominant particle size from autogeneous blasting ranges from near zero to that measured at Delta o of the crater tests; vi. decreasing the crater chart value (v) by subtracting for bench geometry a Delta increment adjustment ranging linearly from a maximum at Delta bo - Delta o for a controlling burden of magnitude Delta o to zero fro a controlling burden Delta a or less or for a controlling burden Delta ss or greater, Delta increment being Delta bo minus Delta o, Delta bo being the value of dbo/N for the given charge weight, dbo being the perpendicular distance from the verticle free face to the center of gravity of explosive charge which produces upon explosion of said charge maximum pressure rise within the material, Delta a is the Delta value at which the volume of the apparent crater is maximum, and Delta ss being the Delta value at which cratering begins; vii. placing the charge at a distance from the controlling burden toward the face of the bench corresponding to the adjusted Delta value; viii. placing the charge at a distance from the noncontrolling free face at the crater test determined value; and ix. detonating the charge.

21. A method comprising: a. preparing a bench free face by conducting blast tests; b. establishing a pattern of cellular units separated by pillars of the ore body to be mined; c. excavating an outer peripheral portion in each cellular unit by stability control blasting so as to develop a buffer zone of broken ore between the central portion and pillars to be formed and to form ramps for access into each cellular unit; d. excavating an inner product control zone within each cellular unit; e. depositing water quality filter beds on the floor of one or more cellular units; f. drilling drain holes horizontally through at least one pillar; g. filling the cellular units with overburden, tailings or mixture thereof; h. constructing dikes above the filled cellular uniT and pillar structure so as to form terrace ponds and pillar pond; and i. filling said terrace ponds and pillar ponds with tailings.

22. The method of claim 21 wherein the stability control blasting is conducted by: i. conducting test crater blasts and preparing a chart by plotting the slant distances to limits of each of the types of fractures in the blasting failure process and to the doming limit, by plotting the slant distances to the crater lip against charge depth and the zone of bond strength destruction against charge depth, R cracks defining the limits of extreme rupture and by plotting the variation in predominant particle size against charge depth from the parameters determined from said blasts; ii. selecting a predetermined limit part which the material in which the blasts are conducted in not to be affected; iii. progressively setting and detonating explosive charges in the direction approaching said limit, each successive charge being decreased in Delta b value and increased in Delta v value so as to progressively increase the Delta v - Delta b difference approaching said limit, the Delta b value being determined from the cratering results using the relation b/N, where b is the bench burden in feet and N is the distance in feet at which cratering begins for the bench charge, the Delta v value being determined from the relation dc/N, where dc is the distance beneath the top of bench in feet to the bench charge; and iv. the placement of the charge being such that the limits of extreme rupture as defined in said chart do not for any given blast extend beyond the predetermined limit.

23. A method comprising: a. preparing a bench free face by conducting blast tests; b. establishing a pattern of cellular units separated by pillars of the ore body to be mined; c. clearing overburden from an extended area of the over-lying ore body using trajectory control blasting; d. tunneling horizontally through said ore body perpendicular to said free face in said pillar areas; e. tunneling through said cellular units parallel to said free face and at the same level as the tunneling in step (d); f. excavating an outer peripherical portion in each cellular unit using stability control blasting so as to develop a buffer zone of broken ore between the central portion and pillars to be formed and to form access ramps into the cellular unit; g. placing charges in the tunnels formed in step (e) and detonating said charges; h. removing the broken ore from within the cellular unit and filling the empty cellular units with overburden; i. constructing ramps above the level of the overburden filled cellular units using overburden; j. utilizing said ramps constructed in step (i) to dispose of excess broken overburden and to predetermine the height of a future reclaimed surface above the mined-out area based upon the volume of excavation and the swell volumes of materials to be disposed of; k. constructing terrace ponds and pillar ponds on top of the overburden; and l. selectively filling terrace ponds and pillar ponds with mill tailing slurry to a predetermined elevation.

24. The method of claim 23, wherein the trajectory control blasting is conducted by controlling the trajectory of material formed as bench geometry surrounding a blast charge in response to explosion of the charge by: i. placing a charge of weight W at a vertical depth Delta v wherein Delta v dv/N wherein dv is the vertical depth, N being the depth of placement of a charge of given weight which first begins to produce upon explosion of the charge fractures on the surface of the material in which the charge is placed; ii. positioning said charge of weight W along a rearward extension of a line perpendicular to the bench free face at a burden b wherein b db/N wherein db is the burden distance and Delta b Delta v + Delta diff wherein Delta diff is a predetermined positive value, the trajectory being substantially in a vertical direction when Delta v is less than Delta b and substantially in the horizontal face direction when Delta b is less than Delta v; and iii. detonating the charge.

25. The method of claim 23, wherein step (h) is carried out by conducting trajectory control blasting.

26. A method comprising: a. preparing a bench free face by conducting blast tests; b. establishing a pattern of cellular units separated by pillars of the ore body to be mined; c. clearing overburden from an extended area of the over-lying ore body using product control blasting; d. tunneling horizontally through said body perpendicular to said free face in said pillar areas; e. tunneling through said cellular units parallel to said free face and at the same level as the tunneling in step (d) f. excavating an outer peripherical portion in each cellular unit using stability control blasting so as to develop a buffer zone of broken ore between the central portion and pillars to be formed and to form access ramps into the cellular unit; g. placing charges in the tunnels formed in step (e) and detonating said charges; h. removing the broken ore from within the cellular unit and filling the empty cellular units with overburden; i. constructing ramps above the level of the overburden filled cellular units using overburden; j. utilizing said ramps constructed in step (i) to dispose of excess broken overburden and to predetermine the height of a future reclaimed surface above the mined-out area based upon the volume of excavation and the swell volumes of materials to be dispsosed of; k. constructing terrace ponds and pillar ponds on top of the overburden; and l. selectively filling terrace ponds and pillar ponds with mill tailing slurry to a predetermined elevation.

27. The method of claim 26, wherein the product control blasting is conducted by: i. conducting test crater blasts at various depths to determine the breakage limits of the material in response to the blasts; ii. preparing a chart by plotting the slant distance to each of the types of fractures in the blasting failure process and to the doming limit from test crater blasts; iii. establishing a grid over the crater formed by each test blast and measuring the particle size of the broken material touched by the grid; iv. preparing a chart by plotting the variation of the predominant particle size which various charge depths at scaled depth ratios Delta ; v. determining in the range Delta d to Delta o from the chart of (iv) the value in the controlling burden direction at which the desired predominant particle size can be achieved, Delta d is the Delta value at which doming begins and Delta o is the value of do/N for the given charge weight, do being the depth of placement of a charge of the given weight which produces upon explosion of the charge maximum pressure rise within the material, and N being the depth of placement of a charge of the given weight which first begins to produce upon explosion of the charge fractures on the surface of the material in which the charge is placed; or in the range Delta o to Delta equals 0 the value at which the desired particle size can be achieved where predominant particle size from autogenous blasting ranges from near zero to that measured at Delta 0 of the crater tests; vi. decreasing the crater chart value (v) by subtracting for bench geometry a Delta increment adjustment ranging linearly from a maximum at Delta bo - Delta o for a controlling burden of magnitude Delta o to zero for a controlling burden Delta a or less or for a controlling burden Delta ss or greater, Delta increment being Delta bo minus Delta o, Delta bo being the value of dbo/N for the given charge weight, dbo being the perpendicular distance from the vertical free face to the center of gravity of explosive charge which produces upon explosion of said charge maximum pressure rise within the material, Delta a is the Delta value at which the volume of the apparent crater is maximum, and Delta ss being the Delta value at which cratering begins; vii. placing the charge at a distance from the controlling burden toward the face of the bench corresponding to the adjusted Delta value; viii. placing the charge at a distance from the non-controlling free face at the crater test determined value; and ix. detonating the charge.

28. The method of claim 26, wherein step (h) is carried out by conducting trajectory control blasting.

29. A mining method including: a. clearing overburden from an extended area of underlying ore by product control blasting; b. excavating in a stepped fashion a grid of cellular units in the exposed ore body, said units being separated by barrier pillars; and c. forming ramps in the pillars as mining progresses downwardly for access to the ore.

30. The method of claim 29, wherein the product control blasting is conducted by: i. conducting test crater blasts at various depths to determine the breakage limits of the material in response to the blasts; ii. preparing a chart by plotting the slant distance to each of the types of fractures in the blasting failure process and to the doming limit from test crater blasts; iii. establishing a grid over the crater formed by each test blast and measuring the particle size of the broken material touched by the grid; iv. preparing a chart by plotting the variation of the predominant particle size with varius charge depths at scaled depth ratios Delta ; v. determining in the range Delta d to Delta o from the chart of (iv) the value in the controlling burden direction at which the desired predominant particle size can be achieved, Delta d is the Delta value at which doming begins and Delta o is the value of do/N for the given charge weight, do being the depth of placement of a charge of the given weight which produces upon explosion of the charge maximum pressure rise within the material, and N being the depth of placement of a charge of the given weight which first begins to produce upon explosion of the charge fractures on the surface of the material in which the charge is placed; or in the range Delta o to Delta equals 0 the value at which the desired particle size can be achieved where predominant particle size from autogenous blasting ranges from near zero to that measured at Delta o of the crater tests; vi. decreasing the crater chart value (v) by subtracting for bench geometry a Delta increment adjustment ranging linearly from a maximum at Delta bo - Delta o for a controlling burden of magnitude Delta o to zero for a controlling burden Delta a or less or for a controlling burden Delta ss or greater, Delta increment being Delta bo minus Delta o, Delta bo being the value of dbo/N for the given charge weight, dbo being the perpendicular distance from the vertical free face to the center of gravity of explosive charge which produces upon explosion of said charge maximum pressure rise within the material, Delta a is the Delta value at which the volume of the apparent crater is maximum, and Delta ss being the Delta value at which cratering begins; vii. placing the charge at a distance from the controlling burden toward the face of the bench corresponding to the adjusted Delta value; viii. placing the charge at a distance from the non-controlling free face at the crater test determined value; and ix. detonating the charge.