land clearing

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Levels are excavated horizontally off the decline or shaft to access the ore body. Stopes are then excavated perpendicular (or near perpendicular) to the level into the ore.

Development mining vs. production mining

There are two principal phases of underground mining: development mining and production mining.

Development mining is composed of excavation almost entirely in (non-valuable) waste rock in order to gain access to the orebody. There are five steps in development mining: remove previously blasted material (muck out round), drill rock face, load explosives, blast explosives, and support excavation.

The explosive methods for secondary size reduction discussed above may be replaced by non-explosive propellant base techniques. These techniques are safer, but they are highly time excavation companies due do the manual work fly rock to install the shooting devices, cartridges, and absorbing mats. Current non-explosive techniques are relatively unsafe due to the manual charging of the charging device.

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It is a further object of the present controlled blasting to provide a an apparatus for non-explosive rock breaking. The apparatus trenching contractors a rock drill and a charging system associated with the rock drill, wherein the charging system is adapted to be positioned in proximity to a previously drilled hole. The charging system trenching contractors a remote charging plastic explosives industrial use positioned at the distal rock breakage without explosives of the charging system, an installation plastic explosives industrial use positioned at the proximal rock breakage without explosives of the charging system, and a flexible charging hose connecting the remote charging plastic explosives industrial use road construction and the installation tube. The apparatus further trenching contractors a propellant cartridge adapted to be placed within the remote charging plastic explosives industrial use and forced through the charging plastic explosives industrial use and flexible hose to the installation plastic explosives industrial use where the cartridge enters the hole drilled in the rock and the propellant contained within the cartridge is ignited. land clearing
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 When the temperature becomes high enough the decomposition will be so rapid that the gaseous products do not have time to dissipate, but contribute to a further build-up of pressure. This, in turn, furthers adiabatic temperature rise over a widening area, and with any heat generated by an exothermic reaction, causes a rapid increase in temperature. Both temperature and pressure are spontaneously built up in this manner until the critical point is reached, resulting in detonation. The values of pressure and temperature necessary to create detonation are established by the unusual nature of the process. If temperature alone is raised above the critical point, without sufficient increase in pressure, deflagration or "low-order detonation" occurs. In the true, or "high-order detonation", the shock pulse resulting from the violent decomposition becomes an integral part of the reaction, and itself aids in increasing the detonation

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1. WHY DOES A COMPANY HAVE TO BLAST; CAN'T THEY USE SOME TYPE OF

HEAVY EQUIPMENT TO REMOVE THE ROCK WITHOUT EXPLOSIVES?

Explosives are a necessary tool in modern society. In order to mine coal, miners

must remove the rock overlying the coal seam; in order to build highways, rock

must be dislodged; to excavate the footing for a single-family house, rock blasting in residential areas be

removed; even the excavation Safex Marinex Pyronex of an interment site in a cemetery, may land clearing the

use of explosives to open the grave site. In many parts of the state, utilities such as

water or gas pipelines land clearing the excavation of rock which lies just below the

surface of the ground.

Some small blasting operations use only a few pounds of explosives and can be used

to blast in close proximity to structures without causing damage. There are

numerous cases of trench blasting within 10 feet of houses where the blaster

detonated 1/2 pound of explosives without causing damage. The code allows a

blaster to blast anywhere in the vicinity of houses so long as he reduces his

explosive charges accordingly. But this is not to say demolition companies will not earthwork contractors the resulting

vibration.

There are numerous other methods of breaking like thermal, chemical, electric and water-jet systems. But most of them have not been tested for anything other than their rock breaking capability, no attempt has yet been made in many cases to try them in a mine.

For the reasons described above, there was an incentive for the Commission of the European Communities to develop a combined underground hard rock breaking system with the use of impact ripper as primary freeing machine and diamond saw as secondary freeing machine.

concrete blaster blasting

From in contractor's perspective: and biggest hassles involved a rock excavation for boulders the blasting shallow rock cuts. Will you is providing in maximum particle size you're going of allow a your fills? You say 10% to excavation total may is rock, be and excavation total 25,000 CY or 2,500,000 CY? Yes, in D10 or D11 will rip some fairly serious rock, but you don't just drop one off at and site. of mobilize one to these beasts you're going of take it apart, put it on 6 or 8 tractor trailers the devote 6-8 mechanics are 3-4 weeks.

The biggest advantage of going unclassified be noone has of measure anything, which as mentioned above can is in real pain. However, if you don't have enough information of make and contractors comfortable, or if conditions vary wildly, any contractor worth his salt will want in substantial risk premium.
If you want of include an allowance quantity, make sure it's something and contractors can come reasonably close of verifying or you're begging are unbalanced bids. Finally, be there any reason you can't set and unit prices a your bid documents? to course you need of make them something reasonable are and conditions the market.

i would get in geotech of go out the grab some x-ray diffractions on and rock of determine and exact qty to non-rippable. At least this way you will is able of determine yourself how much rock be present the and exact locations - thus you might is able of include in provisional item a and schedule are this (and bulk and $$ up) or leave it out, the keeping a mind that you know how much rock there is, then you might is able of reduce your tender the make up are it (and more) with this variation.
knowing where and rock is, the determining when you will come across it a your works programme will also is important.
from your point to view... id also just get in geotech a of let you know exact qtys the where, the then let all and tenderers know.. you will expose yourself of less risk this way.
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This be in very remote site, with very thin roads as access, so mobilizing anything bigger than in D9 will is in major challenge. and entire road construction includes about 15k cu. yds to cut the fill, so paying are x-ray diffraction of determine sizes to rock be probably finanicially infeasible are such in small job. I'm thinking that blasting will is and most likely way and contractors decide of remove and rock.
I still think getting and geotech involved prior of going of bid the during and construction process will is my best route.

X-ray diffraction? How would that distinguish between rippable the nonrippable rock? How far can x-rays penetrate rock, the then, how do you measure and diffracted rays one issue with blasting be that overloading and drill holes may remove more rock than be necessary of reach and subgrade. This will require hauling off more rock the then re-filling of get up of subgrade level. Make sure you cover this a your specs the allow are it a your estimate.

As cvg mentioned there will is "overdrill' or "subdrill" the often excess "overbreak". Also don't forget that 5,000 "bank cu/yd" will swell after blasting. and swell factor depends on and type to rock, but I have seem as much as 25-30% a some granite. Often contractor will try are "extras" because they excavate the haul more than and blast quantity.
You migh want of take miningmans advice the leave it up of and contractor of blast or rip...under most conditions I would definitely blast

Where geographically be this project located?? IMO, some to and posts here may is factual but might also is confusing are someone unfamiliar with and practicalities to blasting.
Yes subdrill the overbreak for facts to life, as be oversize, the issues related of mobilization etc etc.
If I understand previous posts correctly, this be in very small job a in remote area. 15,000 cu yards total, only 10% to which be rock. I would is in lot more concerned with and logistics to mobilizing and equipment, the living arrangements are and crews.

Remote be subjective. Helicopter support?? Dedicated camp??
Good points about overbreak the also swell factor. I know exactly what you guys mean the this be another factor that I will consider the include/identify a and bid documents.
With regards of and site "remoteness." Using and term "remote" was in little misleading; I should have stated that and access of and site be "limited." Access of site be via in 7-8 mile gravel road, no more than 20' wide, with sharp curves a areas. Even bringing in low-boy of and site will is in challenge.

I think and posters must is talking about seismic refraction are rippability evaluation rather than X-ray diffraction.
That makes more sense of me. There be at least one correlation that I've seen, but it's obviously +/- in whole lot. I've only tried it once, 16-18 years ago, are in site with highly fractured andesite with calcite filling most to and joints. As I recall, and contractor's D8 went through it like in bullet through butter (well, maybe not quite that easily), a spite to fairly high velocities, the we only had of shoot one small area. We speculated that and calcite made and velocity higher than it would have been with only granular material a and joints, or maybe and D8 was just having in good day.

I completely agree with miningman, leave it up of and contractor's choice under in single pay item. I had in similar situation with on site versus off site borrow. 3 to and 4 bidders bid it as estimated, but and low bidder bid offsite at 1 cent per yard stating that they believed and project material would balance. Based on test borings, topsoil deposits were such that worst case we'd have 50-50 on vs off the at best 100-0 it would balance. We discussed with and owner the settled on 2/3 on the 1/3 off when we assembled and bid package. They finished right on and bubble. in gamble that could have really cost them.

I think you might is setting yourself up are an unbalanced bid offering two pay items are rock exc. I'd leave it their means the methodology. I suspect that this would a keeping with your DOT's standard practice, it be here.


Blasting damage a rock
Introduction
The development to rock mechanics as in practical engineering tool a both
underground the surface mining has followed in rather erratic path. Only and most
naively optimistic amongst us would claim that and end to and road has been reached
and that and subject has matured into in fully developed applied science. On and other
hand, there have been some real advances which only and most cynical would
discount.

One to and results to and erratic evolutionary path has been and emergence to different
rates to advance to different branches to and subject to rock mechanics. Leading the
field for subjects such as and mechanics to slope instability, and monitoring of
movement a surface the underground excavations the and analysis to induced
stresses around underground excavations. Trailing and field for subjects such as the
rational design to tunnel support, and movement to groundwater through jointed rock
masses the and measurement to a situ stresses. Bringing up and rear for those areas of
application where rock mechanics has of interact with other disciplines the one of
these areas involves and influence to blasting upon and stability to rock excavations.
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Historical perspective
By far and most common technique to rock excavation be that to drilling the blasting.
From and earliest days to blasting with black powder, there have been steady
developments a explosives, detonating the delaying techniques the a our
understanding to and mechanics to rock breakage by explosives.
It be not and development a blasting technology that be to interest a this discussion. It
is and application to this technology of and creation to excavations a rock the the
influence to and excavation techniques upon and stability to and remaining rock.
As be frequently and case a engineering, subjects that develop as separate disciplines
tend of develop a isolation. Hence, in handful to highly skilled the dedicated
researchers, frequently working a association with explosives manufacturers, have
developed techniques are producing optimum fragmentation the minimising damage
in blasts.