1、第 1 页 中文 3712 字 Non-explosive Rock Breaking Technologies for Safe and Continuous Mining K.K.Kabongo Key words： Mining Consultant， Yonke Services (Pty) Limited， 31 Impala Road Chislehurston， Sandton， Johannesburg， RSA ABSTRACT： Several mines in South Africa (SA),like in many other parts of the world,
2、 use drill and blast as means of rock breaking for ore extraction. Despite cost effectiveness high explosive mining does not guarantee optimal total mining costs.Its low energy efficiencies and the hazardous nature of blasting, i.e. poor safety records especially in deep mines, create a need for int
3、ensive reseach and development into safer and more productive technologies. Surely mechanised mining is the ultimate option. Many attempts to use heavy machines in narrow vein deposits at great depths have however resulted in disappointment. Over the last three years, the quest for nonexplosives bre
4、aking technologies has gained momentum. The industry is desperately looking for a face saving system to uplife productivity , ensure safe mining underground, prevent and damaged-control the impact of the devastating HIV/AIDS on the future of mining. Propellant based non-explosive rock breaking is po
5、sitioning itself so as to capture the opinion in the industry. It is considered a midway between cheaper but life-threatening explosives and the capital intensive and uncompromising mechanised mining. Many non-explosive products being trailed in the industry: Swartklip s Boulder , Rocksplitter, Bran
6、drill s Penetration Cone Fracture (PCF),NXCO s Nonex and Altex s Safex to name a few . All these systems have unique merits and they all claim different levels of success in breaking rock under varying conditions, however they all lack the Herculean power (Cunningham 2002), “ the oomph” ,to properly
7、 clean out the rock burdens consistently to the satisfaction of the industry . Fundamentally these systems appear to lack in containing the blast gas energies in the rock to mature burden 第 2 页 fracturing. Rockdusters and Conmin 101 are the newest products to make an appearance . They claim to have
8、addressed this shortcoming with contept. They still have to prove in practicaltrials what appears like an obvious edge over precursors, that capacity of holding gases in blastholes for long duration. Ever though the industry expectation of continuous mining operationts is still a dram , as non-explo
9、sive mining technologies developed to date , have not succeeded to demonstrate such capabilities . This paper intends to discuss the advantages of non-explosive rock breaking systems and to present some results of trial blasts to highlight the way forward towards achieving continuous mining , improv
10、ed health and safety and higher productivity that impacts on the industry bottom lines. 1 INTRODUCTION Drill and blast technology has indisputable merits of breaking the rock. However it is always associated with major health and safety concerns owing to direct aftermath side effects such noise, fly
11、 rocks, toxic fumes, dust, high concussion, accidental detonations and management of misfires. Indeed, the SA industry has managed to scale down and manage these hazards relatively well, given the risks involved and the statistics of accidents recorded to date. However since human life should be rig
12、htly valued, the national expectance is zero accidents at any cost. Thus the reason for this quest by all concerned parties is to work towards a safer mining system that ensures sustainable mining to well take the industry into the future. Cunningham (2002) highlights the major shortcoming of conven
13、tional high explosive mining. He observes that underground ore production is limited by disruption of operations imposed by mining legislation associated with blasting. Full shift continuous operations are impossible owing to the withdrawal time required. Workers vacate the workings shortly before a
14、nd during blasting. There is a working prescribed re-entry period that ought to be observed while blast fumes, noxious gas and dust settle. Non-explosive rock breaking systems claim the advantage of no concern with such huge loss of working time. Several systems have been developed and put forward t
15、o the industry. Despite their subtle differences warranting their individual patents, they all have in common the following claimed features: 第 3 页 Non-explosive low concussion rock breaking Less fines and dust generation Improved hanging wall conditions due to low concussion Low toxic fumes, enabli
16、ng immediate re-entry and continuous mining. 2 NON-EXPLOSIVE ROCK BREAKING SA mining industry has one of the highest rate of mining casualties in the world mainly due to the great depth of mining (2 to 3 kilometres under the ground, ever more ). The unique geotechnical rock conditions are generally
17、characterized by heavily fractured rock in stops and haulages as well as a highly sesmic active ground conditions.High explosive mining does add to the ground conditions described above another safety concern that is born out of the enormous energy generated by blasting,which is often poorly account
18、ed for.Considerable portion of blast energy remains locked up in hanging walls of mining excavations.Without prior warning such energy comes down often triggering bloody falls of ground that frenquently result in accidents varying in intensity from small cuts to multiple fatalities .Tabulated below
19、are statistics of accidents recorded in SA mines for a period of nine years from 1990 to 1999. Table 1. Statisics of high explosive related accidents in SA mines. SA mines accident statistics from 90-99 Total injured Total disabled Total killed Total accidents Fall of ground Misfires Exposure to bla
20、sting fumes Other explosive related accidents 17286 124 99 3 0 1547 29 0 18229 97 417 180 Table 1(above)depicts the horrendous reality of SA mining industry that may be summed up in the following:Every single year high explosives in the industry cause death to over one hundred and fifty people,injure over one thousand eight hundred people and inflic permanent disability to some ten people.This is the
