Environmental Conscious Blasting

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1 Environmental Conscious Blasting X Gumede, SRK Consulting 18 October 2013

2 Overview Relevant Definitions SAMREC Code Triple Bottom Line Four Blasting Deadly Sins Mining Cycle Blast Optimization Model Drilling Blasting Loading Hauling Results Closure

3 Relevant definitions Mining The process of extracting valuable minerals or other geological materials from the earth for economic benefic.

4 Relevant definitions Energy Capacity of physical system to do work Efficient Ratio of useful work to energy used Skillfulness in avoiding wasted time and effort. Effective Having power to produce an effect/s Able to accomplish a purpose Eco-Efficiency Eco-Efficiency green, creating more goods and services using fewer resources and creating less waste and pollution. Sustainable Development Development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Cont

5 Mining redefined Mining The process of extracting valuable minerals or other geological materials from the earth for economic benefit, in an environmental and social responsible manner.

6 Background information SAMREC Code Modifying factors Project feasibility Mining & Environmental footprint.

7 Background information Triple Bottom Line Cont... Mining in peri-urban areas Transforming a mine to be Eco efficient Fewer resources, less waste and pollution. Sustainable businesses are efficient, innovative, profitable & competitive. Eco-efficiency equals cost savings

8 Global warming debate, industrial activities & Planetary climate. Global warming and climate change

9 Four blasting deadly sins Failure to break the intended rock or object into required fragments. Failure to move the broken material to the correct location at a correct shape. Breaking or disturbing the wrong object. Moving the blasted material to the wrong destination.

10 Mining cycle Mine-to-Mill Value Chain Drilling. Charging Blasting Loading Hauling Crushing and Grinding

11 Blast Optimisation Model Mine-to-Mill Value Chain The model deconstructs the mine-to-mill value chain activities. Relates the change in blasting parameters to the savings in energy. Case studies of diverse mining operations a quarry, a large platinum mine and an opencast coal mine Energy savings quantified Financial savings calculated Demonstration of Eco-Efficiency as cost effective.

12 Drill for optimal energy distribution Drilling

13 Blasting Explosive Energy and Carbon rating ANFO comprising 6% diesel fuel by mass, the carbon content is 52.1 kg/ton Thus, carbon emission of ANFO is 191 kg of carbon dioxide equivalent (kgco2-e) per ton of ANFO, 0.25KgCO2-e per Kg of explosives for the surface bulk product Gas End Isentrope Concentratio ns (mole/kg) g/mol g/kg kg/1000k g GWP t-co2e/t CH CO CO H NH H2O N Tota l

14 Drilling, Loading and Hauling Fuel and Carbon rating Diesel is used during drilling, loading and hauling Fuel consumption rates obtained for the different equipment used. Fuel consumption depends on the engine size, the working conditions and between drivers Typical values are selected based on a single type of equipment with consumption values determined

15 Drilling, Loading and Hauling Fuel and Carbon rating Cont..

16 Drilling, Loading and Hauling Total carbon equivalent Cont.. Then, the total carbon equivalent is calculated as Tc = Dt * Cr Cr is an average carbon rating for the diesel fuel that will vary from country to country. For this study, an average Cr equalling 2.5KgCO2-e per litre was applied (Coe, 2005)

17 Electrical energy and carbon rating Bond equation The third theory of comminution developed by Bond (1952). Work index. W = 10W i 1 P F 0.5 Where: W = work input, kwh Ton W i = work index for the specific rock type, kwh Ton P = 80% passing size of the product F = 80% passing size of the feed

18 Electrical energy and carbon rating Bond equation Cont.. Bond work index is significantly reduced by heavier blasting (Nielsen and Kristiansen (1996) Taconite work index of 14.87, is reduced to 10.4, reduction from 80% passing 40cm to 80% passing 30cm Assuming a linear relationship work index will deteriorate by per centimeter size reduction

19 Electrical energy and carbon rating Total carbon equivalent The total electricity used per annum by crushing or milling is then estimated as Ec (kwh/a) = Wi (kwh/ton) x TPC (8) Where TPC is the Total production crushed (tons/annum). To add the benefit of increased throughput due to blasting improvemenst, the total throughput for the new case is factored by the change in throughput: TPC_new = TPC_old*CT_old/CT_new where CT_old and CT_new are the crusher throughputs in t/hr for the old and new cases. The total carbon rating for electricity usage depends on the country in question and can be determined from the national value. In South Africa, the average emission factor is kg CO2-eqt/kWh (Letete et al, 2010)

20 Energy Breakdown Reducing energy bills Drilling - Diesel Blasting - Explosives Loading - Diesel Hauling Diesel 2.5kgCO2E/l Hauling - Diesel Crushing - Electricity Drilling Diesel 2.5 kgco2e Total C02E Loading - Diesel 2.5kgCO2E/l Primary Rock Breaking Explosives 0.25kgCO2E/l Crushing (Primary, Secondary & and Tertiary) Electricity 1.08kgCO2E/l

21 Fragmentation prediction Cuz - Ram equation. Created by Cutznetzov Further developed by Cunningham

22 Factors affecting fragmentation Rock conditions. Tensile strength of the rock, determined by the brazilian test, >15MPa rough fragmentation, <6MPa finer fragmentation. Youngs Modulus of the rock Coarser fragmentation expected at lower Youngs modulus <50GPa than at higher. Density and P-wave velocity of the rock

23 Fragmentation and loading efficiencies Loading Suitable muck pile shape for loading equipment used Efficient digging Muck pile loose enough for faster cycle times Good fill factor

24 Fragmentation and loading efficiencies Infinitely bigger blocks to sizable fragmentation. Break it and move it or Break it and keep it where it is? Correct Burden and Spacing Correct Timing

25 The Model results

26 The Model results Cont..

27 The Model results Platinum Mine Cont..

28 Conclusion Blasting and processing are often dealt with in isolation. Opportunity missed where a small upstream investment provides major returns downstream. The conventional mine to mill model. Is expanded to quantify the additional green house gasses produced and energy changes incurred in the process. In addition, the model contributes to evaluate if there is a total saving in electricity Co-Efficient is cost effective

29 Thank you!