The application of abrasive water jet (AWJ) cutting in quarrying, mining and civil engineering industries has been researched. The work done has yielded a deeper understanding of the performances of suspension AWJ cutting in a range of rock and stone sectors. This project has gone much of the way in meeting its primary objective to show that the technology can give economic, safety, health and environmental benefits.
A new blasting technique with a simultaneous firing of perimeter holes that have radial bottom slots instead of sub-drilling and a bottom charge has been tested in multiple row blasting in the field. The results show that the technique works well under production conditions and that it yields better blasting results than previous best practice smooth blasting; the breakage is better, the remaining wall smoother with near perfect hall-casts and the blast damage shallower at the toe.
In meeting the projects specific objectives the new perimeter blasting technique has demonstrated its ability to decrease the blast damage in the wall and the removal of the bottom charge goes towards the explosive's reduction goal. It is hoped that the new perimeter blasting technique will allow a doubling of the maintenance interval.
Trials were carried out to assess the application of notching and slotting of boreholes in an ore mine. The investigated applications were tunnel and bench blasting. It appears that productivity and cost of underground and surface mining can be improved.
This project has produced a prototype system for primary and secondary slotting operations in quarries with less waste and better health and environmental conditions thus partially meeting the aims. On the negative side it has been demonstrated that for automating block production the costs can be higher and it appears this technique will be only economic for high value or difficult-to-machine materials. Material removal rates are approximately 80% that of competitive techniques (flamejet).
However, important technical advantages exist in the use of water jetting including the reduction of waste, less damage, and improved working conditions and environment.
In the annex to the contract of our project it is stated on page 1 that: 'The quarrying, mining and civil engineering industries need new production methods to;
2) reduce fracturing of rock surfaces during the generation of final surfaces in tunnels, road cuts, mine slopes etc'. We believe that our new blasting technique achieves this.
Objectives and content
The objectives for the research are to demonstrate that abrasive water jet based rock working systems can be developed to:
- Improve the economics of stone and rock excavation with a 25 percent reduction in drilling costs and a 25 percent improvement in production volume for a number of ornamental stone quarrying operations.
- Reduce fracturing of final rock surfaces during blasting in quarries, tunnels and road construction by 50 percent.
- Improve the environment surrounding quarry and mining operations by less waste, noise and dust.
- Improve safety and health conditions by better working methods and automation.
Prototype abrasive water jet based drilling, notching and slotting tools and systems will be developed, along with manipulation systems and methods of using abrasives manufactured from wastes. Drilling, notching, slotting and blasting will be carried out in quarries, a mine and a tunnel to develop new rock working methods. The economics of combinations of conventional and abrasive water jet methods will be assessed and optimised methods developed. Guidelines will be produced for the exploitation of abrasive water jets in rock operations and for the development of equipment and systems for the arduous conditions existing in the quarrying, mining, tunnelling and civil engineering industries.
Funding SchemeCSC - Cost-sharing contracts
136 25 Haninge
4871 Ribeira De Pena
100 29 Stockholm
41335 Larisa - Thessalonki