902283 Computer-aided blast design. An assessment of the latest developments Cunningham, C Quarry Manage Sept 1989, P33-41

Computers can aid in blast design in three ways. Utility appli- cations, accumulating, processing and handling large volumes of data, may be approached using standard spreadsheet software. Expertise applications use knowledge based systems to predict performance. The Kaz-Ram and BOBCAT models applied to fragmentation are illustrated. Simulation programs such as DYNAD2 and DYNAD3 allow study without field testing. The hybrid model SABREX uses a combined simula- tion/expert system approach. Areas of application of com- puter codes and their limitations are discussed.

902284 Stemming length of blasthole and its effect on smooth blasting (In Chinese) Zhang Qi Q Changsha lnst Min Res V9, N3. Sept 1989. P38-42

Optimising the stemming length in smooth blasting is consid- ered on the basis of maximum utilisation of explosive energy. Stemming length is a function of stemming materials, rock properties, and blasthole geometry. Middle graded sand is a better stemming material than clay. For smooth blasting with small (40-50ram) diameter holes, minimum stemming length can be 40, 60, and 80% of hole spacing for soft, medium and hard rocks respectively.

902285 Effective modelling for cast blasting Chung, S H; Tidman, J P Proc International Symposium on Mine Planning and Equipment Selection, Calgary, 3-4 November 1988 P357-360. Publ Rotterdam. A ,4 Balkema, 1988

HEAVE. part of the SABREX blasting program, is a com- puter model to simulate the heave process which is verified by means of high speed photography. The accuracy and sensitiv- ity of the model are demonstrated using examples, blasting with small diameter emulsion explosives or bulk explosives of large diameter, and cast blasting.

902286 Expanded expert system for blast design Scheck, D E Proc International Symposium on Mine Planning and Equipment Selection, Calgary, 3-4 November 1988 P361-367. Publ Rotterdam: A A Balkema, 1988

An expert system to design and evaluate blasts is described. The system comprises 2 modules, a blast design procedure based on theoretical concepts which has been expanded to pre- dict fragmentation and select blasting times, and a knowledge- based expert system for post-blast analysis, limited to vibra- tion effects.

902287 Control blasting at Nickel Plate Mine Bellamy, A F; Christianson, D; Pow, D J Proc International Symposium on Mine Planning and Equipment Selection, Calgary, 3-4 November 1988 P463-470. Publ Rotterdam: A A Balkema. 1988

Wall control practices at the mine, located in a massive, inter- bedded skarn formation, are described. For production, 60 deg walls were required. Experiments were carried out with various loading, pattern and initiation combinations to optimise wall control. The current control drill and blast

IOOA

method, comprising pre-shear holes to create a fracture plane between holes, reducing damage to the walls, and a buffer pattern of 3 rows of holes fired sequentially to minimise wall vibration, is described.

902288 Blast vibration control on curing tunnel lining Loudon, P A; Pringle, L W; Wigginton, R L Proc 1st Regional Conference for Africa, Rock Mechanics in Africa, Swaziland, 3-4 November 1988 P207-211. Publ Marshaltown." SANGORM, 1988

During construction of the 3800m Du Toitskloof (Hugnenot) tunnel through predominantly granitic rock, blast vibration measurements were made in an exploratory tunnel to establish the propagation characteristics of ground vibration. This information, together with damage criteria developed for cur- ing concrete, was used to limit blasting damage close to curing concrete in the tunnel lining, and enabled optimisation of excavation and concreting.

902289 Design, implementation and monitoring of full-face blasts to extend a shaft at Atomic Energy of Canada Ltd.'s underground research laboratory. Hagan, T N; Kuzyk, G W; Mercer, J K; Gilby, J L Proc Conference on Shaft Engineering, Harrogate, 5-7 June 1989 P195-205. Publ London." IMM, 1989

A rectangular shaft sunk in granite was extended using full face blasting. The extension had a circular cross section. Fac- tors considered in blast design included cut design, mud-ring design, perimeter design and initiation sequence. The initial blast design, which used rounds based on an off centre burn cut, is described. SABREX was used to model blasting and improve initial design. Blasting was monitored to enable design optimisation and determine vibration levels. Blast per- formance and modifications are described.

Crushing and grinding

902290 Investigation of the relation between ten per cent fines load and crushing value tests of aggregates (U.K.) Turk, N; Dearman, W R lnt Assoc Engng Geol Bull N39, April 1989, P145-154

10% fines load and aggregate crushing value (fines % under 40 ton load) are widely accepted for assessing mechanical proper- ties of aggregates. Analysis of experimental and published aggregate test results indicates a linear relation between % fines and load, with a varying intercept and slope on the fines v load diagram. Based on this, ACV can be determined from 10% fines load or vice versa. Fit is good up to ACV around 30. The complete relation can be constructed from two test results.

902291 Application of continuous damage theory in determining the distribution function of fragment size for a single fracture Zhu Yi; Xu Xiao-he Proc International Symposium on Modern Mining Technology, Taian, October 1988 P294-299. Publ Taian: Shandong Institute of Mining and Technology, 1988

Some rock is easily crushed, some is not. Fragment size obeys certain distributions. Experimental results suggest natural flaws in the rock play a major role in the crushing operation. This is borne out by Continuous Damage Theory analysis,

© 1990 Pergamon Press pie. Reproduction not permitted