Autostem Product Demonstration

18 September 2015

Compiled by Mike Lyons, Sandvik Offering Development Specialist Narrow Reef

1. Synopsis

Sandvik has introduced a product offering to address the secondary breaking of oversize rocks in mines. The offering is based on the DB120 and DB331 ranges. The DB120 range is aimed at addressing oversize rocks which are already on the floor. The DB 120 range is equipped to drill a hole in the rock and then utilises a hydraulic splitter to split the rock into smaller more manageable pieces. The DB331 range is aimed at addressing over size rocks that are hung up in draw points etc. The DB331 range is equipped with a drilling feed and charge up feed. The rock will be drilled and the charge up feed is then rotated into position and the explosives charge is mechanically placed in the drilled hole for blasting the rock into smaller pieces. Some potential clients have voiced their concerns regarding the use of an explosives cartridge with the DB331 application and Sandvik has commenced a search of the market for suitable non explosives cartridges for use with the DB331 range. Damien Tang, Product Manager DB Range, identified the Autostem product as a potential solution. Autostem was contacted and a product demonstration was arranged at the Lafarge Tygerberg Quarry. The product demonstration was very successful and the Autostem product is capable of addressing most oversize issues on mines in a safe and effective manner. With a few modifications the Autostem product could become a perfect fit for the DB331 application.

2. Introduction For information on the Autostem company and products please visit their website: http://www.autostemtechnology.com Autostem products are being utilised all over the world and they have several authorised companies in various locations appointed as suppliers of the Autostem products. Two well-known explosives suppliers, AEL Mining Services and Maxam are supplying the Autostem products. Mining companies such as Rio Tinto, Arcelor Mittal and Lafarge are also using the product with success. The following information on the Autostem products was taken from the above mentioned website:

• SAFETY o No potential for human error o Sealed units — tamper proof o Completely harmless gas profile suitable for underground use in confined areas o No clearing area required beyond 30 meters o No damage to hanging wall, footwall or surrounding equipment/ structures (no

measurable noise vibration and no shock waves created) o No flying rock or debris o Cartridge remains “static” (minimum movement, if any) when ignited on open ground,

with a combustion sound equivalent to a small cracker o Can’t be used in criminal activities o Extremely safe to use o 18-month shelf life

• EASE OF USE

o Self-stemming in both directions — this is the world’s only double sided self-stemming ‘drop-and-go’ cartridge

o Accelerated loading time by eliminating the need for stemming

o Suitable for above ground, underground and deep level mining applications o Combination of cartridges can easily be joined together for application as booster

charges. The joiner component to join the cartridges fits all cartridge types. o Easy to differentiate between cartridge types (different colours)

• EFFECTIVENESS o Reliable functioning in conventional and open bore holes o Waterproof units — application on land and under water o Sequential firing capability (pyrotechnic and/ or shock tube) o No pulverisation of ore — high value commodity recovered (no fines/dust)

• HOW IT WORKS o The Autostem Cartridge requires no stemming and is simply dropped into a borehole by

the operator. o The initiating wire is then connected to the blaster’s firing cable and initiated by a

conventional shot exploder. o The secondary built-in igniter is ignited and consequently ignites the gas generating

propellant bed in the cartridge tube. o When initiated in a borehole, the proprietary compound in the cartridge ignites to produce

high volumes of harmless gas at very high pressures. o This gas then works against the rock from within the borehole, which is automatically

stemmed by the actuation of the built-in stemming mechanism of the AutoStem Cartridge. When the tube diameter reaches the bore hole diameter, the radial force on the bore hole surface increases due to the pressure build-up, causing fracturing, breaking and heaving of the rock (or concrete) structure. The cartridge obturation mechanism ensures a tight gas seal on both ends of the cartridge, thereby preventing any gas leakage.

o The AutoStem Cartridges can also be joined together in different combinations in a borehole, to augment the total charge delivered to the rock. This simple application makes the AutoStem Cartridge very user friendly, leaving the end-result achievable completely up to the operator.

SAFETY The AutoStem Cartridge offers unparalleled safety. When initiated in an unconfined environment, due to a lack in pressure build-up, the proprietary compound contained within the AutoStem Cartridge will not undergo its combustion reaction, rendering the AutoStem Cartridge entirely harmless if not used within a borehole. A clearing area of 20m – 50m is recommended (there is minimal throw rock with the AutoStem Cartridge), and the rock can be immediately re-approached because there are no harmful gasses. Because the cartridges do not detonate, there is no fire, flame, spark or explosion caused. Classified by the United Nations under either UN 0323 or UN 0432, these cartridges are deemed safe for transport, even on a passenger airplane, and have a shelf life of 18 months. Unlike conventional explosives, the AutoStem Cartridge emits no shockwave on initiation, which means that there is no potential for damage to existing surrounding structures, equipment or on-site personal. Due to the very controlled initiation, there is no flying rock, dust or harmful emissions.

3. Product demonstration On the 18th of September 2015 a product demonstration was held at the Lafarge Tygerberg Quarry. The size of rocks broken up during the demonstration ranged from approximately 2.0m3 up to in excess of 10m3. The main rock type mined at the quarry is Hornfel or Malmesbury Shale and it has an average UCS of 250 MPa. The hole sizes used in the demonstrations were 34mm and the depth of the holes varied and were up to 1m deep. The observers stood approximately 50m away from the rocks being broken during demonstrations 2 to 4 and stood behind a steel hut for the 5th demonstration. Demonstration 1 The first of the demonstrations was a 40 gram cartridge which was set off on the ground about 1.0m form the observers to illustrate that the cartridge is safe when not confined, and in the case of an incident during the handling of the product the possibilities of serious injuries are very slim.

Figure 1: A 40 gram cartridge set off on the ground When the cartridge was set off it produced a very low “puff” sound and the cone was ejected from the cartridge with a small flash as indicated in Figure 1 above. No detonation or explosion took place. Demonstration 2 The rock broken up during demonstration 2 was approximately 1.5m x 1.0m x 1.2m and the before and after images can be seen in Figure 2 below.

Figure 2: Approximately 2m3 rock before and after The rock was charged with a 40gram cartridge. It was clear that when the cartridge was set off in the hole (confined space) it was no longer “harmless” and it broke the rock into approximately 5 smaller pieces. There was a significantly louder “bang” with virtually no dust or smoke. On inspection the remainder of the barrel of the hole could be seen clearly as in Figure 3 below.

Figure 3: Barrel remaining on broken rock Demonstration 3 The rock broken up during demonstration 3 was approximately 2.0m x 1.0m x 1.2m and the before and after images can be seen in Figure 4 below.

Figure 4: Approximately 2,4m3 rock before and after The rock was charged with 2 x 40gram cartridges. The rock was broken into several small rocks.

Demonstration 4 The rock broken up during demonstration 4 was approximately 2.4m x 1.6m x 1.2m and the before and after images can be seen in Figure 5 below.

Figure 5: Approximately 4.6m3 rock before and after The rock was charged with 2 x 40gram and 1 x 60gram cartridges and as can be seen from Figure 5 above, the rock was completely broken up into a pile of small rocks. Demonstration 5 The rock broken up during demonstration 5 was approximately 2.4m x 2.6m x 2.0m as indicated in Figure 6 below.

Figure 6: Approximately 12.5m3 rock The rock had a single hole in the centre of the rock and it was charged with 1 x 100 gram cartridge and 1 x 100 gram booster. The rock was broken into several smaller rocks as is indicated in Figure 7 below. Figure 8 below indicates that the rock had been broken up to the end of the hole (approximately 1.0m deep) where the remaining socket can be seen.

Figure 7: Approximately 12.5m3 rock broken into smaller rocks

Figure 8: Rock broken up to end of hole with remaining socket From Figure 8 above it can be seen that the remaining portion of the rock has several fractures and the remainder of the rock could be pulled apart with the bucket of a loader. During this demonstration it was explained that the horizontal hole with the 200 gram charge could produce some fly rock and the observers were advised to stand and observe from behind a steel hut.

During all the demonstration during which rocks were broken up there were loud “bangs” followed by very little (insignificant) dust or smoke. Only in the last demonstration were a few small flying rocks observed.

4. Conclusion The following conclusions were made during the demonstrations:

• Safety: The product is very safe due to the following: o No detonator is used with this product o There is no conventional explosion o Product is very simple to use and requires very little training o Product is sealed and tamper proof o Virtually no dust, smoke or gasses produced during the breaking process o As observed in demonstration 1, the cartridge can do very little harm when not confined

a hole o The product is not classified as an explosive and does not need to comply with the

onerous explosives regulations • Effectiveness

o All the rocks were broken very effectively o No shockwaves or vibrations experienced during the demonstrations o Virtually no dust, smoke, shockwaves or flying rocks could allow for oversize rocks to be

broken up during shift times without vacating the whole mine or area. Results can be viewed right after cartridges were set off.

o Product is self-stemming and does not require additional stemming Taking the above conclusions into consideration it is the opinion of the author that the Autostem products are very well suited for secondary breaking applications in mines. It is also the author’s conclusion that with some small modifications from both Sandvik and Autostem, the Autostem products will be a perfect fit for the DB331 range.

5. Acknowledgements The author wishes to thank Messrs. Josy and Jonathan Cohen and their staff for arranging the product demonstration and sharing their technical knowledge and information published in this document.