Engineering & Mining Journal

JUL 2017

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74 E&MJ; • JULY 2017 www.e-mj.com OPERATING STRATEGIES Blasting specialist Dyno Nobel recent- ly reported on an interesting and effec- tive blasting-optimization project at an unidentifi ed surface mine. The project, according to the bulk product manager, Dave Hunsaker, required working closely with the customer to determine if benefi ts could be derived through the introduction and implementation of selected Dyno No- bel Titan bulk explosives technologies. In past years, the mine traditional- ly used only augured emulsion/ANFO blends. Wet holes were dewatered and loaded with the same blend normally used for dry hole applications. The ben- efi t of this is that the mine was able to utilize one pattern for both wet and dry holes. Patterns vary from bench to bench, based on the different geological forma- tions found throughout the pit. Once the 16-inch-diameter holes are drilled, it's not uncommon for them to be loaded and "slept" for several weeks at a time. Water can be a problem in certain ar- eas of the mine, making dewatering next to impossible. Several attempts were made in past years to pump emulsion blends in an effort to solve the dewatering and NO X problems associated with augur- ing product into wet or partially wet holes. Traditional gassed emulsions were tested, unsuccessfully. Most of the holes loaded with this product and technology failed to perform properly because the stemming material used by the mine sank into the emulsion column, causing the down lines to either sink into the blast hole or to break, depending on the amount of slumpage that occurred. Because the mine had such poor re- sults with gassed emulsions, the fi rst se- ries of tests in the recent project were de- signed to demonstrate that Dyno Nobel's suggested products had the capacity and capability of preventing the stemming material from migrating through the load- ed emulsion column. An initial pattern was drilled and 10 holes on the end of the pattern were loaded with Titan XL1000. The holes slept for several days and each hole was monitored for slumpage during this period. The outcome was positive, none of the holes slumped at all. Members of the blast crew indicated that this prod- uct seemed to resist slumpage better than past products. Patterns were shot successfully, and Hunsaker said the en- couraging results provided the initial con- fi dence the mine operator needed in order to progress the testing program. Next, a series of patterns were partial- ly loaded with Titan XL 1000 with the in- tent of comparing a number of items side by side, including: • Visual ground breakage, • Hole slumpage, • NO X emissions, • Loading rates, and • Cost reduction. Test results showed the visual ground breakage was very similar. The holes did not slump and actually were much better than holes loaded with the 50/50 blend, NO X was eliminated entirely, and production rates were maintained. The initial positive outcomes resulted in the mine loading and shooting entire pat- terns using Titan XL1000 over the next several months. Although the Titan trucks held less product, the delivery rate was 60% faster, and turnaround at the plant took less than half the time it took to load blend trucks. A substantial cost reduction was achieved because equal or better performance was achieved even with a reduction in total pounds being loaded into the ground. Several months passed as equipment was acquired and confi gured to meet the needs of the customer and when this was completed, the site was fully converted to Titan technology. After the new trucks arrived, the shots looked very good from the surface, but eventually complaints were received from shovel operators working in certain areas of the pit about hard digging in the toe area of the shots. Based on this feedback, it was determined that Dyno Nobel's Dif- ferential Energy line might provide a better solution to solve the toe issues that had been reported and observed in about 30% of the shots. Differential En- ergy technology allowed the operators to adjust the explosive energy in each hole based on the geology. After Differential Energy was deployed the hard toe issue disappeared. A three-seg- ment loading scheme was introduced, pro- viding a toe explosives density of 1.28 g/ cc with much lighter densities in the upper portions of the holes depending on the geo- logical formations being blasted. In summary, Hunsaker explained that the value added to the customer's blast- ing program included: • Reduction of volume of explosives load- ed into the blast hole by up to 9.2% as the process transitioned from using heavy Trial, Error and Success — Finding the Right Blasting Technology Pays Off New bulk explosives, combined with equipment designed specifi cally to effi ciently deliver and handle them, prove to be benefi cial for a surface mine seeking to improve the performance and cost-effectiveness of its blasting program.

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