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Laboratory scale single hole blastability test in blue grey and steel grey hematite from Bailadila Mine, India
Luleå tekniska universitet.
National Mineral Development Corp.
2000 (English)In: Fragblast, ISSN 1385-514X, E-ISSN 1744-4977, Vol. 4, no 1, p. 35-53Article in journal (Refereed) Published
Abstract [en]

In the Bailadila hematite mine in India, we can find one of the worlds most difficult ore to blast due to the high density- and high longitudinal wave velocity of the hematite ore. The product of these two physical parameters is called acoustic impedance (Z). For the Bailadila Blue grey- and Steel grey hematite ore, Z was found to vary between 24-33·106 kg/m2s. This range of Z is much higher than all rock materials tested so far by Lulea University of Technology, where the range was between Z = 12-20·106 kg/m2s. The hematite, in the blocks tested, had many pores and in full scale cavities also called 'blow holes' could be found at the mine. These pores in the model blocks may influence the breakout in tests. In the model blocks there were also some irregular weakness planes found. The main problem in the Bailadila Mine was too many boulders, especially when blasting in the Blue grey hematite ore. Lab. scale single hole blasting tests were undertaken in hematite blocks with the dimension 100×300×300 mm at Lulea University of Technology to determine the blastability of the two most common types of hematite occurring at Bailadila, Blue grey- and Steel grey hematite. The data were compared to already known results from earlier lab. single hole blast tests in hard rocks. The measured critical burdens for the Bailadila ore were very small because of the high acoustic impedance. This means that the ore is very difficult to blast, in fact the most difficult to blast of all rock and rocklike materials so far tested at Lulea University of Technology. Based on the state of the art of blasting technology today the best explosive to use in the Bailadila hematite would therefore be an explosive with high density and detonation velocity. That would improve breakage and reduce the number of boulders. Other suggestions for improvement of fragmentation are to initiate each hole on a separate delay, increase the number of intersection holes and change the spacing/burden ratio.

Place, publisher, year, edition, pages
2000. Vol. 4, no 1, p. 35-53
National Category
Other Civil Engineering
Research subject
Mining and Rock Engineering
Identifiers
URN: urn:nbn:se:ltu:diva-14263DOI: 10.1080/13855140009408062Local ID: d9ddedc0-0c9a-11dd-9b51-000ea68e967bOAI: oai:DiVA.org:ltu-14263DiVA, id: diva2:987217
Note

Validerad; 2000; 20080417 (ysko)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-02-02Bibliographically approved

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