Blasting News Volume 27 I Issue 1 I 2018
IN THIS ISSUE: • AEL Mining Services’ IntelliShot™, perfectly suited for every blasting need • Pulling together through trust and commitment: a partnership between AEL Mining Services and Debswana • Global Supply Chain launches newly reconfigured fleet of vehicles
Blasting News
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ASTING NEWS BLASTING NEWS BLASTING NE CONTENTS 3
AEL INNOVATION: AEL Mining Services’ IntelliShot™, perfectly suited for every blasting need
4
AEL PARTNERSHIPS: Pulling together through trust and commitment: a partnership between AEL Mining Services and Debswana
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AEL IN THE FIELD: AEL product showcase at the annual MTE show in Kathu, Northern Cape
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AEL IN THE FIELD: AECI Mining and Chemical Services Namibia (Pty) Ltd participates in the 2017 Namibian Mining Expo & Conference
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AEL SUPPLY CHAIN: Global Supply Chain launches newly reconfigured fleet of vehicles
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AEL REMOTE CAPABILITY: AEL’s expanding footprint in Francophone West Africa
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AEL TECHNICAL CAPABILITY: Case Study - First emulsion trial blast at Ohorongo Cement Quarry in Namibia
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AEL THOUGHT LEADERSHIP:
EXPLOSIVES TODAY Series 4 No.6 18
AEL Unearthing Value: Mongolia
Editor’s Note Reflecting on 2017, we celebrate our successes built on the foundation of our value proposition, intelliBlast™, which is an holistic and flexible approach to help our customers on their unique journey to optimal blast outcomes. Optimal blast outcomes reduce inefficiencies and operating costs and improve productivity and output. AEL continues its drive for increased value for its customers by acutely focusing on the needs of our customers, working with them to improve our understanding and jointly developing and delivering innovative solutions. Innovation is key to remaining relevant to the market we serve. Therefore, we constantly keep our finger on the pulse of future trends in order to develop our existing product and service portfolio. In this issue, we introduce our latest electronics innovation, IntelliShot™ which is perfectly suited for every blasting need. We also demonstrate how AEL has developed a strong competency for servicing remote mining operations in some of the toughest conditions in Africa through a well-established and successful African business, and is actively expanding its international business in partnership with leading regional players. In our AEL Technical Capability and AEL Partnerships sections we share insights from our subject experts in Francophone Africa and Botswana as well as on the international front in Mongolia. AEL’s ability to provide world-class blasting services wherever it operates has made it a partner of choice in the mining, quarrying and construction sectors. In line with this, we extend an invitation to our stakeholders to join us at international events in 2018 for AEL’s thought leadership presentations and showcases of future technologies. Some of our past events are documented in our AEL in the Field section where you can read about AEL’s 2017 product showcase at the annual MTE show in Kathu, Northern Cape and AECI Mining and Chemical Services Namibia (Pty) Ltd’s participation in the 2017 Namibian Mining Expo & Conference. Finally, to round off this issue, our regular Thought Leadership section offers you the latest EXPLOSIVES TODAY issue. We hope you enjoy your read and look forward to keeping you abreast of our journey of innovation in 2018. AEL is a dedicated organisation that serves the needs of its customers by ensuring that we continuously reflect our BIGGER values (Bold, Innovative, Going Green, Engaged and Responsible) in all our activities. To fulfil our commitment of keeping you in touch with the AEL world, we invite you to subscribe to Blasting News by visiting our website www.aelminingservices.com and clicking on the Publications tab or to follow the AEL conversation on Twitter, Facebook, YouTube and LinkedIn. Enjoy your read! Eubulus
Front cover image: Underground Tunnel Maldonan
Pillay
Editor Tel: +27 11 606 0313 eubulus.pillay@aelms.com
Disclaimer This publication does not necessarily reflect the views and opinions of AEL Mining Services Limited management. The copyright to this publication rests in AEL Mining Services Limited. Other product and corporate names used in this publication may be trademarks or registered trademarks of other companies, and are used only forexplanation and to the owner’s benefit, without intent to infringe.
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© AEL MINING SERVICES 2018
AEL Innovation
AEL Mining Services’ IntelliShot™, perfectly suited EWS for every blasting need - Contributor: Christo Peltz, AEL Product Manager As leading innovators, AEL Mining Services and DetNet are proud of their ability to satisfy the needs of their clients by constantly innovating their range of Electronic Delay Detonator (EDD) technology. Based upon many years of research and an in-depth look at customer needs, AEL Mining Services’ IntelliShotTM range is perfectly suited to cater for the blasting wants and needs of our customers. IntelliShotTM is one of the components of AEL’s value proposition named intelliBlast™ which demonstrates to our customers that we are perfectly positioned to deploy into their operations seamlessly, through our innovative and agile products and services. Through intelliBlast™, we highlight to our customers that our approach can help them improve their balance sheet and pursue cash preservation, which is imperative in the current economic climate. “IntelliShotTM is our most advanced wire based Electronic Detonator blasting solution ever. It merges class-leading technology with simplified user interfaces, making complex blasting simple, fast and accurate. The system is entirely designed and engineered in South Africa,” explains Christo Peltz, Product Manager at AEL Mining Services. The IntelliShotTM system consists broadly of three components: • The IntelliShotTM detonator, • The CE4 tagger, and • The Blast Commander. The IntelliShotTM detonator has been developed with over 30 years of electronic detonator learning incorporated in the detonator design for improved resistance to blasting phenomena generated during detonation such as an electromagnetic pulse, static electricity, shock- and pressure waves. “Safety is at the heart of everything we do. We have gone to even greater lengths to ensure our customers benefit from the excellent safety record they have come to expect with our products. Our new system utilises an Application Specific Integrated Circuit (ASIC) electronic chip and not the average off-the-shelf microprocessor. The same technology is used in mission critical electronics such as aerospace and defence applications where a guaranteed outcome is required,” says Peltz. The memory of the IntelliShotTM ASIC has been upgraded to have 15 times more storage capability, thereby allowing more functions and features not previously possible; while the programming speed has been increased by sevenfold. “Even the communication leads have been upgraded to be tougher with increased abrasion resistance, increased ability to stretch and tensile properties that ensure the detonator remains functional in the most demanding of applications,” explains Peltz. The system can fire 16 000 detonators in a single blast and uses encrypted radio frequencies to set up a blast network which can stretch over several kilometres. The product suite is Blasting News
The IntelliShotTM System
mainly focussed on large surface blasting operations where the designs may vary from simple line blasting all the way through to complex designs requiring multiple decking on several synchronised box cuts and/or benches. “What makes IntelliShot™ unique is that the system merges industry-leading technology with ease of use. The product has been designed to handle complex blasting requirements in an easy manner,” states Peltz. The Blast Commander automatically detects detonators connected to it and can monitor the voltage level in the last detonator to confirm the blast design is getting the required energy from the control equipment right up to the point of firing the blast. All of the enhancements have been introduced to make the product more robust, save time and ensure the user has a successful blast on time, every time. As part of the system, the tagger is GPS enabled allowing the GPS coordinates of a detonator to be stored in the tagger memory against the individual detonator IDs. This can be used to simplify fault finding on large benches, should it become necessary. “Our market research indicates that our system is the only Electronic Detonator solution that can perform encrypted wireless synchronisation and control of the equipment. The system incorporates built-in long range (3km) transmitters/ receivers so there is no need for additional external antennae,” explains Peltz. The product uses the latest electronic communication protocols such as Wi-Fi and Near Field Communication (NFC touchto-communicate). The Commander module has a multi role capability as it can act as a Bench (blast) device, Base (remote) device or RF Repeater. Another great feature is the remote control (Wi-Fi) facility of the Commander. This device can be wirelessly controlled using the tagger, smartphones- or tablet running specific CE4 software. “All of these features combine to give the user, ease of use, speed of connection and communication, extremely robust detonators and control equipment (IP57 rated) which leads to accurate, successful blasts, on time,” concludes Peltz. Page 3
AEL Partnerships
Pulling together through trust and commitment: a partnership between AEL Mining Services and Debswana Contributor: Ronald Joseph, Managing Director - Business Development, AEL Botswana. been involved in various activities at Debswana’s operations, and have helped grow their business by incorporating AEL’s intelliBlast™ value proposition.
DEBSWANA
AEL Mining Services and Debswana’s partnership of trust and commitment dates back to the commencement of mining operations by the Debswana Diamond Company, over 30 years ago. To date, AEL has continued to supply explosives and expert blasting services to Debswana’s four diamond mines in Jwaneng, Orapa, Letlhakane and Damtshaa.
The intelliBlast™ approach, which emphasises a customisable solution to blasting services, is materialised in terms of advanced product offerings, and blast optimisation consultation work in conjunction with each operation’s requirements. “Our approach is fully in line with our intelliBlast™ value proposition. Customisation for efficiency is the basis of our intelliBlast™ philosophy that we execute for Debswana,” adds Joseph. “Our plants at Debswana are capable of manufacturing up to 3700 tons of emulsion between the two sites,” says Joseph. “This is not only a very cost effective solution, but also allows flexibility, as well as last minute changes on the bench to suit the different blasting requirements.” These on-mine facilities enable AEL to service Debswana’s bulk explosive requirements from either one of the two plants and allows for any contingency plans. The two plants are the only bulk emulsion plants in the country.
“Our path with Debswana started in the early 1970s when AEL was first registered in the country. Following the commencement of Orapa Mine operations in 1971, AEL was registered in 1973 and at that time the supply of explosives and blasting services was performed from South Africa. After Jwaneng mine was operationalised in August 1982, AEL shifted the focus to establishing a meaningful partnership with Debswana that would help grow the industry in the country,” says Ronald Joseph, Managing Director of AEL Mining Services in Botswana.
One of AEL’s offerings for Debswana is the “Down-The-Hole” (DTH) blasting solution. In addition to this, AEL continues to offer the “Prime-Load-Tie-in and Shoot” (PLTS) service to Debswana as and when required. AEL has over the years continued to help Debswana shape the future of Botswana by providing solutions that contribute to sustaining the mining processes at the various Debswana operations. One such key contribution is the recent success of the North East Corner project where AEL, together with Debswana was involved in all the blasting design and execution.
Through this journey, in 1981, AEL and Debswana collaboratively established the country’s first bulk emulsion manufacturing plant at Jwaneng mine. In 1983 another plant was established to service the explosives distribution sites at Orapa and Letlhakane mines. Since then, AEL has
“An extensive collaborative approach with Debswana is how we have built the prosperous relationship we have today. We have learned, particularly in the case of Debswana, that a true partnership is built through active engagement, trust and ongoing commitment,” Joseph concludes.
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© AEL MINING SERVICES 2018
AEL in the Field
AEL product showcase at the annual MTE show in Kathu, Northern Cape The 11th MTE show in Kathu, Northern Cape, took place on 22 June. With over 230 registered visitors and 50 exhibitors including suppliers of pumps, mining machines, gear boxes, lifting equipment, trackless equipment, fire suppression equipment and conveyor technology, the exhibition created the ideal networking and product showcase opportunity for AEL Northern Cape. AEL exhibited our range of portable charging units, electronic delay detonators and a mobile manufacturing unit (MMU).
AEL’s Mobile Manufacturing Unit (MMU) on display
AEL’s Divisional Director in the Northern Cape, Thabo Makeki, together with AEL’s technical experts engaged with potential customers and industry partners at the exhibition. Kathu is the iron ore capital of the Northern Cape and is home to Sishen mine, Khumani mine, Tshipi é Ntle mine and other small mining operations. The town and accompanying industrial area of Sishen developed due to iron ore mining activity in the Kalahari. The AEL team manning the exhibition stand
Blasting News
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AEL IN THE FIELD
Hosted by the Namibian Chamber of Mines and themed “Reaping the Benefits of Mining Investment in Namibia”, the 2017 Namibian Mining Expo and Conference took place on 26 and 27 April in Windhoek. More than 100 exhibitors from the country’s major mines and mining industry service providers participated in the event. These included the likes of AECI, Rio Tinto, Namdeb, B2Gold and Rössing among others. The mining industry remains one of the largest contributors to Gross Domestic Product, constituting 12.5 percent in 2015, and contributes an average of 50 percent to Namibia’s foreign exchange earnings. “The benefits of a modern and well-run mining sector to the Namibian economy are plenty and remain important drivers for economic growth,” said Veston Malango CEO of the Chamber of Mines. The Mining Conference, which is an integral part of the expo, covered crucial topics such as water security concerns, uranium market dynamics and mining contribution to national development, among others.
AECI Mining and Chemical Services Namibia (Pty) Ltd participates in the 2017 Namibian Mining Expo & Conference
Commenting on the local mining industry, Malango emphasised the benefits the economy reaps from its well-established mining sector. The Namibian mining industry provides jobs to about 9 000 permanent employees, of which 95.5 percent are Namibians and only 5 percent are expatriates. Together with contractors, the industry provides jobs to about 19 000 people and given a multiplier effect of 7, the industry provides livelihoods to over 100 000 people. In all endeavours the industry has developed solutions to urgent problems, hand-in-hand with government, local authorities, employees, unions and the Namibian nation at large. AECI Mining and Chemical Services Namibia was represented by Ritzema Nel (Country Manager Namibia) who together with the AECI and Chemical Initiatives teams exhibited a wide suite of products at the exhibition. Source: www.namibian.com.na
The product range on display
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© AEL MINING SERVICES 2018
AEL SUPPLY CHAIN
Global Supply Chain launches newly reconfigured fleet of vehicles
AEL’s Global Supply Chain division recently launched new 250cs vehicles used to deliver PEX and Initiating Systems as part of an optimisation initiative to improve transport delivery efficiencies and reduce costs. According to Sibusiso Khumalo, AEL’s Transport Manager (Global Supply Chain), the efficiencies will be derived from replacing the fleet of 550cs vehicles with smaller 250cs vehicles. AEL will benefit from efficiencies such as 25% improvement in payload, lower vehicle running costs and improved fleet utilisation. This optimisation initiative will yield a saving of R3.7m through rationalising the fleet mix. Blasting News
Mervin Nattar (Unitrans), Norberto Terclavers (AEL), Conrad Klaasen (Unitrans), Denvor Govender (AEL) and Sibusiso Khumalo (AEL)
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AEL Remote Capability
AEL’s expanding footprint in Francophone West Africa
by Mark Benning
Taparko MAKO LEFA
Yanfolila HoundE
BISSA Boungou
Mark Benning - Managing Director Francophone West Africa
“The last 15 months have been significant in the history of AEL’s Francophone West Africa business portfolio” reports Managing Director Mark Benning. Between November 2016 and March 2017 the AEL business portfolio in Francophone West Africa was awarded 4 new contracts to supply products and services to new mining projects in the region worth USD106 million over the next 5 years. These include 3 contracts as a sub-contractor to African Mining Services (AMS) in Senegal, Burkina and Mali at the Mako, Boungou and Yanfolila projects respectively. The 4th contract was with Endeavour Mining at their flagship Houndé project in Burkina Faso. It is exciting times for the Francophone team with mobilisation having started on all 4 sites at the time of writing and first blasts had been successfully taken at Houndé on 4th August, at Boungou on 25th August and at Mako on 13th September and at Yanfolila on 15th October. The total capital investment across all 4 projects is more than USD8.0million and includes 2 new emulsion plants (at Mako and Houndé) as well as 5 MMU’s. In some cases, the availability of used assets has allowed AEL to deploy in time for project commencement until items with long lead times are delivered. Exactly 111 new employees have been recruited, trained and deployed for the 4 projects. “We put this recent success down to a change in our approach to tendering on new opportunities and it seems to have paid off. Of 5 finalised tenders issued in the region during this period, AEL won 4 and it clearly indicates that the decision to change our strategy was the right one.” “Our management team sat down and had an honest look at our lack of success in recent years and identified a number of key areas for improvement. Ultimately it was Page 8
about being more competitive and meant finding ways of reducing input costs and adding value.” “We have worked with AMS before and are thrilled to be working with them again. They have a growing presence throughout the region and our values are similar in many ways. Being awarded 3 projects in 3 different countries meant that we could look at ways of exploiting synergies across the region.” “We are particularly excited about our involvement in the Houndé project and our first time relationship with Endeavour Mining who have built a portfolio of projects in the region over the last few years, and who continue to look for opportunities having also acquired the Karma Mine in Burkina Faso and Avnel’s Kalana project in Mali. They are also investing in expanding their Ity mine in Côte d’Ivoire and in exploration. We are looking forward to building our relationship with Endeavour through the Houndé project.” “It was a challenging year for everyone but it’s a nice challenge to have. Watching all the planning and resources come together is very rewarding for the team. All the projects have potential upside in terms of the life of mine which is likely to be enhanced through the first few years of development. We want to be there all the way to the end so will be working hard at meeting our clients’ requirements and unlocking value for the benefit of all concerned.” “On behalf of AEL Mining Services, we would like to thank our new customers for putting their trust in us and for providing us with an opportunity to partner with them for the next few years as we work together unlocking wealth at these new projects.” In addition to the new projects, AEL has also successfully extended its contracts at all 3 Nordgold mines to © AEL MINING SERVICES 2018
AEL Technical Capability
December 2020 at Lefa (in Guinea) and Taparko as well as to December 2021 at Bissa, Nordgolds flagship mine, both in Burkina Faso, and which includes the stand alone heap leach operation at Bouly. Negotiations commenced in June 2016 but were only concluded in October 2017. The combined contracts are worth an estimated USD70million over the contract periods.
“Nordgold is a key customer and it was important to secure this contract to maintain and consolidate our leading market position in the region. Extending our relationship will deliver significant intrinsic value for both parties and once again we thank Nordgold for the confidence shown in our company and its people throughout the region to deliver”.
Charging on the bench at Mako (15 November 2017)
Dawn breaks at Houndé on the morning of the first blast Friday 4th August. Transferring the emulsion from the delivery tanker into the MMU.
Construction of the Mako emulsion plant site underway in Senegal (August 2017)
The new Houndé plant under construction (December 2017)
Magazines under construction at Mako in Senegal (July 2017)
Blasting News
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AEL Technical Capability
Business challenge In February 2015 Ohorongo Cement (Pty) LTD and AEL Namibia embarked on an emulsion test trial project for both cost savings and reduction of manual labour to be measured and agreed, focused on increasing the drill and blast efficiencies and potentially changing to a new explosive at Ohorongo Cement quarry. The Ohorongo cement quarry operations are located approximately 45km north of Otavi in the central northern part of Namibia. Ohorongo Cement’s quarry currently averages around 400 000m3 of raw material per annum and projected an increase in production of about 500 000m3 at the end of 2017. Prior to the commencement of the project, a site meeting was held to discuss the drilling and blasting (D&B) designs of the current practices at Ohorongo cement. AEL Namibia made recommendations on how to improve D&B efficiencies for the long term as well as to reduce manual labour on their current blast practises. AEL Namibia provided a full Prime. Load. Tie-in and Shoot (PLTS) service to Ohorongo cement to introduce the new explosives and accessories to be used for the trial blast. A bench of 43 holes was prepared and charged with SP200 Eco emulsion and a total of 18866 BCM was blasted at a powder factor of 0.46kg/m3. The following accessories were used for the trial blast: Trunk Line
• • • • •
Multi SPD
Pentolite Boosters
IED
Multi SPD 25m/500ms Trunk Line 6m/17ms Trunk Line 6m/42ms Instantaneous Electric Detonator (IED) 400g Pentolite Booster OD 53mm in hole
Solution The ground conditions of the prepared bench were in a good condition and easily accessible with a repump MMU. The following blast design was used as the holes had been drilled for an ANFEX design prior to the blast.
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Burden (m)
3.5
Spacing (m)
4
Sub drill (m)
0.3
Design Ratio
1.14
Stemming (m)
2
Depth (m)
25
© AEL MINING SERVICES 2018
All holes were sleeved using 150mm tubing at 150microns thickness to prevent emulsion leaking away from the blast holes. The AEL team consistently monitored the cup samples to ensure the density stayed within specification due to the hole depth of 25m of which the diameter was only 95mm. A cup sample of 1.04g/cc was required to achieve a 1.20g/cc average in hole density. The final toe density around the booster was calculated to be 1.27g/cc to ensure full detonation of the explosives column.
Emuldens was used to calculate the in hole densities of the S200 eco emulsion
SP 200 ECO Emulsion
Toe Density
Outcome AEL performed well with the assistance from the production team of Ohorongo Cement. The use of sleeves proved to be a tough battle as sharp rocks kept on damaging the sleeves inside the hole, due to the significant deviation and drilling angle of 80 degrees. The use of a 95mm hole at a depth of 25m in soft rock has proven it difficult to drill a proper pattern where the toe burden and spacing deviates significantly from the surface burden and spacing. The blast was successful and a lot of knowledge was shared with the production team that was led by Rassie Shilongo of Ohorongo Cement. The Customer was pleased with AEL’s expertise and services and has requested to sign a 3 year exclusive supply contract. AEL has offered the Surface Blasting Competency course to the customer to enhance the skills of their production team. The AEL team was led by Gunther Doll – Operations Manager and Henry Oswald –Field service superintendent.
Blasting BlastingNews News
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AEL Technical Capability
On Bench Charging with R59, Emulsion delivery was done on bench with G&H Transport to increase the production cycle and to reduce the manual labour from the current blast practise using ANFEX.
All Holes were closely checked and inspected by AEL
The picture shows good ground movement and a smoother high wall which was achieved compared to the ANFEX blast The yellow arrow indicates where holes were missing from the initial blast design causing bad back break in the rear left corner of the blast, larger rocks can be seen on the upper part of the muck pile.
Good fragmentation was achieved.
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Š AEL MINING SERVICES 2018 Š AEL MINING SERVICES 2018
AEL Thought Leadership
EXPLOSIVES TODAY Series 4 I No 6
The use of ANFO in Surface Blasting Ken Meiring - Senior Explosives Engineer
ANFO is an explosive mixture of Ammonium Nitrate (AN) and Fuel Oil (FO). These two constituents act as oxidiser and fuel in the reaction that takes place during detonation. The normal fuel oil used is dieseline, and the trade name for ANFO made at AEL Mining Services is ‘ANFEX®’. Owing to its effectiveness and low cost, ANFO gained wide acceptance in all types of blasting operations, since its introduction in the 1950’s. This issue of Explosives Today deals with the use of ANFO mixed on bench, i.e. in blastholes exceeding 50mm in diameter.
Blasting News Blasting News
Ammonium Nitrate - Definition “Ammonium Nitrate emulsions and gels, intermediate for blasting explosives” – means a mixture of ammonium nitrate with one or more other oxidisers and one or more fuels, with or without the addition of any other substance which is intended for use in the manufacture of explosives or for on-site manufacturing.
of the Explosives and Mining laws and regulations. Properties of AN Ammonium Nitrate is hygroscopic and
Storage of AN AN must be stored in a suitable magazine constructed and licensed as set out in the appropriate Explosives and Mining laws and regulations. This typically also covers an allocated area for parked transport trucks. Conveyance of AN AN may be transported by box truck, tanker on road, by rail and by ship in a variety of containers and bags as specified in the appropriate chapters
Figure 1 Bulk storage of Ammonium Nitrate Prills
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AEL Thought Leadership
Figure 2 Storage of bagged AN prill and Handling equipment
therefore very soluble in water. As a result it is quickly rendered inert in wet holes and this is its most serious disadvantage. AEL manufactures ammonium nitrate prill in two forms; Ammonium Nitrate Emulsion grade (AN-E) or dense grade; and Ammonium Nitrate ANFO grade [AN-A]. AN-A prill is porous to allow for the absorption of fuel oil as can be seen in figure 5.
Figure 3 Transport of AN by “Rapid Reloader” - Tanker
energy yield declines. Too much fuel (insufficient oxygen in mixture) also causes excess CO to be liberated in the detonation gases, whereas insufficient fuel (excess oxygen in mixture) encourages the generation of greater volumes of nitrous fumes. Because it is much more serious to have too little fuel than too much, and because the exact mix can never be achieved, AEL specifies 6% fuel, with a maximum range of 0.5% either side.
The dark grey areas indicate the fuel
Property
If the density of the FO is p g/cc
Anfex® - Poured
Density (g/cc) 0.78-0.8 Velocity of Detonation (m/s) 2000 – 3000 Water resistance Nil Fragmentation Good Heave Excellent Ideal Delivered Energy (MJ/kg) at 20MPa 2.84 Bulk delivered Energy (MJ/kg) at 20MPa 2.27 Relative Effective Energy (REE) at 20MPa 100 Relative Bulk Strength (RBS) at 20MPa 100 Ideal Delivered Energy (MJ/kg) at 100MPa 2.26 Bulk delivered Energy (MJ/kg) at 100MPa 1.81 Relative Effective Energy (REE) at 100MPa 100 Relative Bulk Strength (RBS) at 100MPa 100 NOTE – The energies and strengths have been determined using the AEL Vixen_i detonation code. Density (pneumatically loaded Anfex (g/cc) 0.90 to 1.05
oil within the prill cavities. AN-E is used in the manufacture of AN based bulk explosives where AN solution is not readily available. Figure 4 shows that about 6% by mass is required to obtain an oxygen balanced mix which produces maximum power and minimum blasting fumes. With too much or too little fuel, Page1414 Page
Figure 4 Prill showing diesel absorption
ANFO Mixing Ratio Maximum power during detonation is achieved by mixing the AN and FO in the approximate ratio of 94:6 by mass i.e. or
94kg AN with 6kg FO 100kg AN with (100/94) x 6 = 6.4kg FO
Then volume of FO/100kg AN = (6.4/p) = 7.5 litres per 100kg Where p = 0.85 g/cc or 3.75 litres/50kg bag On Site mixing of ANFO The manufacture of ANFO is normally regulated by the appropriate Mining and Explosives laws and regulations. Ammonium (ANA)
Nitrate
ANFO
grade
The porous prilled AN manufactured by AEL Mining Services is treated with special anti-caking and crystalhabit modifying agents that ensures low friability (less than 2%), i.e. its formation of dust. The anti-caking agent counters adherence between prills and promotes free flow during handling, while the crystal-habit modifier raises the temperature at which a phase change of the AN crystals occurs. This phase change is an important cause of prill deterioration and setting up (caking) in AN transport and storage at temperatures in excess of 32°C. ANA remains stable to prill deterioration
AELMINING MININGSERVICES SERVICES2018 2018 ©©AEL
AEL Thought Leadership
AEL Mobile Manufacturing Units (MMU)
ANFO output kg/ min
AN hopper capacity (tons)
Capability
A Series A12T
200/500/750
12
Capable of auguring ANFO
H Series H20T
250/500/750
7
Heavy ANFO MMU capable of auguring the ANFO and the full range of AEL’s doped1 or blended2 explosives products
E Series E15T and E20T
750
5 and 7
MMU capable of pumping or auguring the full range of AEL’s doped1 or blended2 explosives products
Doped 0 – 35% ANFO 2Blended – 54 – 74% ANFO
1
Doped – Emulsion & additives have been added 2. Blended – AN or ANFO, emulsion added 1.
Figure 5 Effect of fuel oil content on strength of ANFO
even under hostile environments of up to 40°C. Fuel Oil and Substitutes Various types of fuel may be used because solid fuels are not as effective as liquid fuels in ANFO. Black or recycled oil is increasingly being considered as a replacement but they are still being researched with the absorption of waste oil by the prill the main focus. The absorption takes longer due to the higher viscosity of the waste oil, resulting in the outer bag being coated in a thin film of oil, which in turn interferes with the heat sealing of the bags. ANFO Mobile Manufacturing Units (MMU) AEL manufactures 3 model series, the choice of which depends on the scale of the mining operation and the diameter of the blast holes.
and D = 250mm MC = 0.785 x 0.8 x 2502 MC = 39250 g/m The density of ANFO made with ANA has a nominal density of 0.78g/cc but can be as high as 0.82g/cc, depending on the size and depth of the hole. Also, blasthole diameters can vary significantly from their nominal size and these two factors must be taken into account when accurately predicting the mass of ANFO per unit length contained in a blasthole. If this is not of critical importance, controlled loading experiments will determine the correct factors to apply. The blasting effect of ANFO relative to other explosives is assessed on the basis of their relative energies per metre run of blasthole.
Use of ANFO
ANFO can be combined with emulsion to create customised bulk explosives products. These are referred to as doped or blended emulsions with the generic term for blended emulsion being “Heavy ANFO”. This product is an excellent replacement for ANFO in damp conditions where the blast is fired immediately after charging is completed. The added emulsion helps to “waterproof” and protect the prill from water which allows for the heave characteristics of ANFO to be harnessed. Due to the thickness of the explosive as a result of the prill content, this range of products can only be augured. Typical velocity of detonation, VoD, range between 4000 to 6000m/s depending on hole diameter and confinement, (Rock properties.)
A booster is a charge of high energy explosives which is reliably initiated by a detonator or by detonating cord. AEL manufactures Pentolite boosters in three sizes of which two can be used with ANFEX in surface applications.
MC = 0.785 x p x D2 OR MC= p x D2/1273 Where D = blast hole diameter (mm) p = density of explosives (g/cc)
Blasting News
Heavy ANFO (Doped and Blended bulk emulsion)
Initiation
ANFO is especially effective in dry blast holes exceeding 100mm in diameter. The mass per metre run of blasthole (MC) is given by the equation
For example, where p = 0.8g/cc
Table 1. AEL MMU
Figure 6 MMU in action
For best performance, the booster selected should be the largest that will easily fit the blasthole. All Pentolite boosters have one or two axial holes large enough to accommodate both shock tube or electronic detonators or 10g/m detonating cord. Page 15
They are waterproof, have low impact sensitivity and possess the advantage over cartridged explosives of being more convenient to store and use. Pentolite boosters are preferable for use in bulk explosives usage due to their high VoD characteristic. As blasthole diameter increases, the ability (sensitivity) of ANFO to initiation decreases, but the reliability of propagation increases. Thus a charge as small as an 8D detonator, can initiate ANFO (having been loaded pneumatically resulting in sufficient fine material to assist with propagation) in blasthole diameters below 51mm. As blasthole diameter increases, so the size of the initiator required also increases. Historically, poured ANFO was used in conjunction with detonating cord in blast holes. This practice led to desensitisation or side initiation of the ANFO in the hole with the result of poor blasting. Large diameter holes (>80mm) using ANFO and detonating cord Research has proven that side initiation due to the use of detonating cord with ANFO in large diameter holes negatively affects the fragmentation and thus loading rates and causes poor floor conditions due to ineffective breaking. Where side initiation does not occur and the product is desensitised, then based on work with ANFO in pipes, “dead pressing” occurred within a radius of between 50 to 102mm around the detonating cord. This equated to a 10% loss in the explosive mass/hole and in theory an increase to approximately 38% loss in explosive mass/hole in 165mm holes. Small diameter holes (<80mm) using poured ANFO and detonating cord In smaller hole diameters (typically around 80mm and less) the detonating cord causes density to exceed the critical density at which ANFO can detonate, (known as “dead pressing”) and leads to poor or incomplete detonation. This required that additional boosters be placed in the explosives column to maintain propagation of the detonation wave. As shock tube and electronic initiating systems replaced detonating cord, it has become necessary to double prime only in deeper holes or where geological conditions exist. e.g.when a particularly hard band of rock within the softer material requires an additional Page1616 Page
Product
Emulsion
ANFO
Fuel Oil
Straight emulsion
100%
0%
0%
Doped emulsion
65 – 90%
35 - 10%
0%
Blended emulsion
46 – 26%
54 – 74%
3 – 3.5%
Typical VOD (m/s)
4500
3500
NA
Table 2. Comparison of products
Acceptor Diameter (mm)
Bulk Anfex® 76 - 127
140 - 215
Bulk Anfex® Eco 250 - 311
76 - 127
140 - 215
250 - 311
X
X
Donors 60g 150g
For use in holes less than 76mm in diameter X
400g
X X
X
Table 3. Booster compatibility
booster for a second deck of explosives (See Figure 7). Additionally, a 10 – 20% improvement in the mean and distribution sizes of the fragmentation and increased burdens and spacings became possible. Blasting with ANFO in wet hole conditions Good blasting results can be achieved with ANFO in wet conditions but only if one of these two methods are considered: Dewatering and sleeving Dewatering equipment, in our experience, always leaves some sludge or water at the toe of wet holes. This will dissolve the ANFO at the toe and render it ineffective and as the toe is where the most difficult breaking conditions are found. A plastic sheath may be used to encase the ANFO to protect it against this moisture. The insertion of “lay-flat’ sleeving can be a slow and onerous procedure and where holes are making water, this practice has two inherent risks.
1. The ANFO column may be ‘pinched’ out by water pressure around the sleeving. This will decrease the breaking effect of the ANFO and may even result in detonation failure in these holes. 2. Despite every precaution taken, the ‘lay-flat’ sleeving may be torn by projections in the side of the blasthole, allowing water to penetrate the sleeving and destroy the ANFO. Water resistant toe charges In this method the wet portion of the hole is charged with cartridged water resistant explosives such as Magnum® Buster Gel. To preserve good breaking, this decoupled explosive should have at least the same relative energy of the fully coupled ANFO. Sealing of the holes above the water level is achieved by slitting the cartridges and then dropping these onto the toe charge.
Figure 7. Use of extra primer to improve explosives distribution in hard rock bands
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Figure 8 - Use of ANFO with water resistant toe charge in wet conditions
ANFO is then loaded until the required column rise has been achieved. It has been shown that, even in dry blastholes, ANFO does not always have the ability to break out toes. In such cases a more powerful explosive such as Magnum Buster Gel should be used as a bottom charge. This has the advantage of maintaining or even increasing burdens and spacings, while a water resistant explosive is immediately available with the advent of wet holes. Additional options to consider when using ANFO in wet conditions include: • Using a water resistant ANFO based product such as Heavy ANFO where the hole toe is not completely flooded • Using underground bulk emulsion
from a Smart Trailer instead of cartridges as the base charge • Bulk emulsion NOTE: Before adopting the practice of slitting cartridges, permission must be obtained from the CIE or DMR depending on which inspector has jurisdiction over the operation. The advantages of these methods are: a) Simple and reliable a) Fragmentation can be maintained b) Little time is lost in charging up c) The toe charge will serve as an effective booster for the ANFO d) Holes full of water may be completely charged with the water proof explosive and fragmentation maintained with the same burdens and spacings.
Conclusion ANFO is usually a cost effective explosive, especially in softer rock formations. Its disadvantages are: a) Low relative energy b) Lack of water resistance Its advantages are: a) Lower price b) Low transportation and storage costs for AN c) AN transport not restricted to scheduled explosives trains d) Simple to use e) High loading rates f) Gives good blasting results under the right conditions
DISCLAIMER AND INDEMNITY Any recommendations given by AEL Mining Services (AEL) in respect of this document are given in good faith based on information provided. AEL does not however warrant that particular results or effects will be achieved if the recommendations are implemented, due to potentially unknown aspects and/or conditions. AEL further does not accept liability for any losses or damages that may be suffered, as a result of the customer acting, or failing to act, on the recommendations given. Explosives Today, Series 2 No 30 Surface and 31 Underground by M Beattie December 1982 and KS Ireland March 1983 respectively are replaced by this series. COPYRIGHT All copyright that subsists in this publication together with any and all diagrams and annexures contained herein, which shall include all and/or any ideas, plans, models and/or intellectual property contained in this document vests in AEL. Any unauthorised reproduction, adaptation, alteration, translation, publication, distribution or dissemination (including, but not limited to, broadcasting and causing the work to be transmitted in adiffusion service) of the whole or any part of this document in any manner, form or medium (including, but not limited to, electronic, oral, aural, visual and tactile media) whatsoever, will constitute an act of copyright infringement interms of the Copyright Act No.98 of 1978 and will render the transgressor liable to civil action and may in certain circumstances render the transgressor liable to criminal prosecution. This document remains the intellectual property of AEL. Intellectual Property: All ideas, concepts, know-how and designs forming part of this publicationbelong to AEL, save for where it is clearly indicated to the contrary.
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intelliBlastTM is a holistic and flexible approach to help customers on their unique journey to optimal blast outcomes. Through optimal energy expenditure we ensure predictable blast outcomes for significant profit growth. AEL Mining Services Tel: 011 606 0000 Email: company.email@aelms.com Web: www.aelminingservices.com