Safe Practices of Site Mixed Explosives System

Site Mixed Bulk Loading Explosives System – Safe practices *** Partha Das Sharma (B.Tech-Hons. In Mining Engg.) E.mail – [email protected], [email protected] 1. Introduction: Site mixed bulk loading explosives system (SMS) provides a wide range of benefits which add value to mine blasting operations. These benefits are to increase mine productivity and reduce mining costs by optimizing blast results and increasing the efficiency of the drill-blast cycle at customer operations. A Bulk Mobile Delivery (BMD) vehicle can be defined as ‘a vehicle mounted plant which carries its own ingredients, can manufacture or blend site mixed explosives (SME) and contains it own delivery system for charging into boreholes as per the site requirement’.

SMS provides the Bulk mobile delivery (BMD) equipment and operating personnel necessary for delivery of bulk explosives into the borehole, as per the blast pattern. Solar group of Explosives Company support the blasting activity at customers’ mines by committing the expertise and resources to provide a continuous and reliable supply of high quality explosives when they need

Author: Partha Das Sharma, E.mail: [email protected]

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it. The control panel(s) on board the BMD allow for charging the explosives in the hole at any desired horizon to allow the mining engineer to make the most efficient use of explosive energy in the rock strata to be blasted. The BMD is designed to charge in both Shovel and Dragline deep boreholes with automatic retractable hose-reel mechanism to ensure water displacement. At the mine site, gassing agent is injected into non-explosive pre-mix just before delivery pumped into down the boreholes; where it attains its explosivity in about 15 to 20 minutes of delivery. The quantity / metering of gassing agent is determined based on pre-mix characteristics, the charge density / column-rise desired etc., as per the blast design and other field requirements. The delivery metering counters are calibrated according to the desired final density down-the-hole before commencing actual charging operation in the field. This ensures charging / quantity delivered into a borehole as required by blast design. The Sp. Gravity of the emulsion matrix before and after gassing is checked frequently (with the help of a beaker or cup – thus called “Cup Density”) to calculate amount of bulk explosives pumped. Electrical and mechanical counters are provided on the BMD to check the volume; and this volume multiplied by Sp. Gravity (Cup density) gives the quantity of explosives pumped into a borehole. The objective of our technical program / services is to provide technical information and technical assistance to our customers. This permits the optimization of blasting practices, and the safe, efficient utilization of products and techniques. 2. Safety equipment / device on BMD may include: (i) Emergency kit (ii) Emergency stops (iii) Fire extinguishers (iv) Battery isolator (v) Fuel isolator (vi) Ant-static Delivery Hose with diameter less than explosive’s critical diameter (vii) Chain link for Earthing. 3. Following knowledge required by personnel to achieve the performance criteria: (i) Authorities to operate a BMD (ii) Types and properties of explosives materials (iii) Materials capacity of BMD (iv) Mixing parameters and ratios (v) Identification of incompatible materials and methods of segregation (v) Safety and emergency procedures and equipment associated with the loading and operation of BMD (vi) Mixing and Charging operation (vii) Configuration, accessories and working parts of BMDs (viii) Loading equipment of BMDs and methods (ix) Recording and reporting requirements (x) Transport emergency procedures (xi) Explosives discharge methods and requirements (xii) Placarding and signage requirements 4. Safe Practices while operating the BMDs for use of SMS : A. At the plant safe practices for loading of pre-mix: (i) Select and wear personal protective equipment appropriate for work activities, (ii) Inspect work area and establish, barricade and signpost loading area, (iii) Identify, address and report potential risks and hazards,


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(iv) Segregate incompatible goods prior to loading BMD according to legislation and Codes of Practice (v) Inspect mobile processing unit (BMD) for safe loading of explosives materials (vi) Ensure attachments comply with standards and licensing requirements (vii) Placard mobile processing unit (BMD) and attachments to show the goods carried, hazchem identity and emergency information according to legislation and Codes of Practice (viii) Check that safety equipment is fitted and ready for use according to legislation and Codes of Practice (ix) Calculate batch quantities for ingredients to manufacture explosive to specification, and check availability of ingredients (x) Apply parking brake throughout materials loading operation (xi) Load materials in a safe manner to prevent spillage or injury to personnel and observe emergency procedures (xii) Record the details of all materials loaded according to site procedures and legislative requirements B. Safe practices for Transportation to site: (i) Carry out vehicle pre-start checks (ii) Confirm and adhere to pre-planned route (iii) Operate vehicle according to road conditions and in compliance with established mine safety rules and speed limit (iv) Follow emergency procedures for accidents that result in a dangerous situation (v) General precautions and rules regarding handling and transportation of explosives shall be observed C. Safe practices during charging of boreholes at the Mine site: (i) Select most appropriate borehole discharge point and lay hosepipe over blast hole (ii) Confirm the identity of blast hole and explosive loading requirements with relevant personnel as per the blast design. Only necessary minimum persons shall be allowed. (iii) The area surrounding the BMD, not less than 10m in all direction shall be kept free of rubbish or any combustible material. (iv) Before mixing and delivery from BMD to any borehole, the vehicle shall be properly earthed with chain link. (v) Ensure that, hose with anti-static properties only should be used. (vi) Regulate the discharge of explosive to the blast hole to achieve specified weight or stemming height as per the blast design (vii) Complete loading hole and prepare vehicle for next blast hole by ensuring area is clear and safe to move vehicle (viii) No smoking and no open flame should be allowed within 60m of BMD (ix) Due care shall be taken to ensure that the pre-mix is pumped into properly drilled holes and there is no spillage. (x) Charging of the explosives shall be done in such a manner that to ensure continuity of the explosive column in each borehole. For deck charging also continuity is to be ensured. (xi) Area of loaded holes shall be conspicuously marked by visible bright red flags during day light hours and by fluorescent signs during night hours and unauthorized entry shall be cordoned off effectively. (xii) All operation of charging and firing shall be done in daylight hours only. (xiii) Explosives should not be allowed to sleep over in the borehole, unless required permission obtained from the DGMS. (xiv) Complete records required by site and legislation


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(xv) In case of misfires, precautions as laid down in various coal / metal mines regulations shall be strictly followed. (xvi) The entire operation of loading, transportation and charging of explosives to the site shall be placed under a competent and capable mining engineer. D. Safe practices after completion of charging: (i) After completion of charging operation, the BMD system including hose should be emptied of explosives by evacuating compressed air flushing with water. At the end of the operation for the day, the BMD including hose shall be completely cleaned and the vehicle shall be parked at the support plant. (ii) All spillages of explosives shall be collected and destroyed at a safe place and the effluents are discharged after proper treatment.

5. Specific safety requirements for all blasting operations: * The employer shall designate one employee qualified as a blaster, to be in charge of blasting at each location where blasting operations are being performed. * No explosives or blasting agents shall be abandoned. * Smoking, firearms, matches, open flame lamps, and other fire, flame, heat or spark-producing devices are prohibited in or near explosive magazines or while explosives are being handled, transported or used. * When blasting is done persons and machineries shall be removed from the area beyond danger zone or the blast shall be covered, before firing, with a mat or mats so constructed as to control the throw of fragments. * The blaster shall be responsible for using every reasonable precaution such as visual and audible warning signals, flags, and barricades, to ensure employee safety.


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* Blasting operations in the proximity of overhead power lines, communication lines, utility services, or other services and structures shall not be carried on until the operators or owners have been notified and measures have been taken to ensure the safety of the same. * Due precautions shall be taken to prevent accidental discharge of electric blasting caps by current induced by radar, radio transmitters, lightning, adjacent power lines, dust storms, or other sources of extraneous electricity. These precautions shall include: (a) The suspension of all blasting operations and removal of employees from the blasting area during the approach and progress of an electrical storm. (b) The posting of signs warning against the use of mobile radio transmitters on all roads within one thousand feet of the blasting operations. * Empty boxes, paper and fiber packing materials which have previously contained high explosives shall not be used again for any purpose, but shall be destroyed by burning at a location approved by the blaster, and no person shall be permitted near the site after the burning has started. * Containers of explosive materials shall not be opened within fifty feet of any magazine. In opening cases, non-sparking tools shall be used, except that metal slitters may be used for opening fiberboard boxes. * Explosive materials that are obviously deteriorated or damaged shall not be used and shall be destroyed by or under the direction of the blaster. * Flagmen posted on highways to stop traffic during blasting operations shall be stationed far enough away (outside danger zone) from the blasting for their own safety. * Transportation of explosives- Vehicle used to transport explosives on the job site shall have a non-sparking floor and side members and shall contain a suitable fire extinguisher. Explosives and blasting caps shall not be transported in the same vehicle. * Loading of explosives or blasting agents - No holes shall be loaded except those to be fired in the next round of blasting. * Drilling shall not be started until all remaining butts of old holes are examined for unexploded charges, and if any are found, they shall be disposed of before work proceeds. * No person shall be allowed to deepen drill holes which have contained explosives or blasting agents. * No loaded holes shall be left unattended or unprotected. * The explosives used in wet holes or holes that may become wet shall be water-resistant. * Initiation of explosive charges - Primers for use in blasting shall be made up only as required for each round of blasting. * No blasting cap shall be inserted in the explosive materials without first making a hole in the cartridge for the cap with a non-sparking punch.


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* If there are any misfires, it should be handled as per DGMS stipulation. * For electric cap blasting, bus wires, connecting wires and lead wires shall be insulated single solid wires of sufficient current-carrying capacity. * Blasters, when testing circuits to charged holes, shall use only blasting galvanometers powered with a silver chloride cell especially designed for the purpose. * Only the blaster making the final check on the wire connections shall fire the shot. * In any single blast using electric blasting caps, all caps shall be of the same style or function, and of the same manufacture. * Electric blasting shall be carried out by using blasting circuits or power circuits in accordance with the electric blasting cap manufacturer's recommendations. * When firing a circuit of electric blasting caps, every reasonable precaution shall be exercised to ensure that an adequate quantity of delivered current is available, in accordance with the manufacturer's recommendations. --------------------------------------------------------------------------------------------------------------------Author’s Bio-data: Partha Das Sharma is Graduate (B.Tech – Hons.) in Mining Engineering from IIT, Kharagpur, India (1979) and was associated with number of mining and explosives organizations, namely MOIL, BALCO, Century Cement, Anil Chemicals, VBC Industries, Mah. Explosives etc., before joining the present organization, Solar Group of Explosives Industries at Nagpur (India), few years ago. Author has presented number of technical papers in many of the seminars and journals on varied topics like Overburden side casting by blasting, Blast induced Ground Vibration and its control, Tunnel blasting, Drilling & blasting in metalliferous underground mines, Controlled blasting techniques, Development of Non-primary explosive detonators (NPED), Hot hole blasting, Signature hole blast analysis with Electronic detonator etc. Currently, author has following useful blogs on Web: • http://miningandblasting.wordpress.com/ • http://saferenvironment.wordpress.com • http://www.environmentengineering.blogspot.com • www.coalandfuel.blogspot.com Author can be contacted at E-mail: [email protected], [email protected], ---------------------------------------------------------------------------------------------------------Disclaimer: Views expressed in the article are solely of the author’s own and do not necessarily belong to any of the Company. ***


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Safe Practices of Site Mixed Explosives System

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