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Post by pickle on Jan 17, 2014 6:26:59 GMT -5
Hello, I am new in this forum and I am very interested in knowing if there has been a bench height change withing a same mining operation, where, why was it done, and what were the consequences (machinery changes for instance). Thank you very much!
Andrea |
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Post by John on Jan 17, 2014 6:46:54 GMT -5
Hello, I am new in this forum and I am very interested in knowing if there has been a bench height change withing a same mining operation, where, why was it done, and what were the consequences (machinery changes for instance). Thank you very much!
Andrea |
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Post by pickle on Jan 17, 2014 7:30:37 GMT -5
Bench height as in the distance between one ramp and the next (one higher and the one below) in open pit mine walls. See the attachment! Thanks! |
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Post by pickle on Jan 17, 2014 7:34:08 GMT -5
Reasons for changing the bench height once the operation has begun is, for example, changing to a smaller bench height to lessen the dilution factor, or change to higher bench heights to haul more quantities of material at a time (excuse my english, I am Chilean). I just don't know where it has been done, why, how and what were the consequences, as I need to study the case.
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Post by John on Jan 17, 2014 8:13:09 GMT -5
Reasons for changing the bench height once the operation has begun is, for example, changing to a smaller bench height to lessen the dilution factor, or change to higher bench heights to haul more quantities of material at a time (excuse my english, I am Chilean). I just don't know where it has been done, why, how and what were the consequences, as I need to study the case. |
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Post by pickle on Jan 20, 2014 13:31:14 GMT -5
Thanks!!! And thank you for your response!! Cheers! |
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Post by tygwyn on Jan 20, 2014 17:00:26 GMT -5
Surely bench height in an opencast would vary from one opencast to another,dependent on number of seams worked and overburden thickness between each seam.
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Post by John on Jan 20, 2014 17:13:33 GMT -5
Surely bench height in an opencast would vary from one opencast to another,dependent on number of seams worked and overburden thickness between each seam. |
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Post by tygwyn on Jan 20, 2014 17:30:57 GMT -5
Surely bench height in an opencast would vary from one opencast to another,dependent on number of seams worked and overburden thickness between each seam. To be honest,no idea, But if Metal mineral lodes are the same Worldwide as in the UK,more vertical than horizontal,then i cannot see a bench system working. |
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Post by John on Jan 20, 2014 17:40:16 GMT -5
I've only worked in one metal mine, Tin/Silver in Tasmania, and it came as an orebody, not a seam. I believe the Mt Isa Copper mine is the same, large orebody. At Renison Bell they worked stopes, at Mt Isa, only read how they mine it, they work a sort of cut and fill stope method.
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Post by drgjs on Mar 2, 2014 7:18:36 GMT -5
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Post by smshogun on Mar 10, 2014 20:00:31 GMT -5
Normally bench heights are changed due to mineral or ore density as most are blasted.
Normally the drilling is restricted to a maximum depth for blasting down to the power required above certain defined depths, depending on borer type; as the power needed increases to the square as the drill depth exceeds its recommended depth. Normally you would use a smaller bench height at the top of a seam as this contains lower or poorer quality material and while it is viable to mine you don't want it mixing with better quality material during processing or refining, as you get into a quality material you increase the shelf height to blast as much out as possible as the largest bench height, then reduce the height as you reach the poorer material at the bottom of the seam.
Basically it comes down to economics and environmental conditions or regulations, here in the UK blasting out benches is carefully regulated and rigorously enforced so you need to blast as much out as possible if you only blast once a week as you need to blast sufficient material to keep machines and processing plants working all week; it would be embarrassing to run out of material before the weeks end and pay men to do nothing. |
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Post by Minutor on Mar 31, 2014 1:40:05 GMT -5
Hello, I am new in this forum and I am very interested in knowing if there has been a bench height change withing a same mining operation, where, why was it done, and what were the consequences (machinery changes for instance). Thank you very much!
Andrea The main reasons for changing bench height are (1) a change of equipment often associated with an expansion in output or a modernisation of a pit or (2) pushing back an open pit to access deeper ore. You will sometimes find pits with different bench heights in overburden and ore, for example overburden might be in the range of 15m to 20m with production benches in a 5m to 10m range depending on the geology / grade control requirements. Usually a "push-back" involves the removal of the smaller production benches. As far as machinery goes obviously the blast hole rig has to be bigger for higher bench heights, you are blasting more rock so bigger trucks and bigger loaders, probably electric rope shovels. For lower bench heights you could use hydraulic shovels / excavators. |
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