Geology & GeoMetallurgy

Geology & GeoMetallurgy 2017-03-23T09:44:23+00:00
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RC splitters (12 replies)

Gruppen
1 year ago
Gruppen 1 year ago

I am in the interesting position of having a change in our drill and blast contractor. Our new contractor is purchasing a new downhole hammer rig that we will be able to convert to RC for shallow (50m) holes for grade control work and shallow resource definition. The interesting opportunity is that we can have involvement in the set up of the splitting/sampling system on the rig. (It has never happened before!) At the moment I am leaning toward a rotary cone system and like the look of the SandvikRotaport. Anyone had experience with these? Any better suggestions! We need to deliver a 2 kg sample with duplicates every 20 or so.

Carl Jenkins
1 year ago
Carl Jenkins 1 year ago

Sounds good - Rotary cone splitter is the way to go, especially if you are going to be hitting wet material.

Rahil Khan
1 year ago
Rahil Khan 1 year ago

The geotechnical properties of the material in which you will be drilling with RC will determine if the results will be reproducible. The cone splitter will be best in loose material and very difficult, having doubtful results in plastic material.

Gruppen
1 year ago
Gruppen 1 year ago

Good point. Fortunately all the production areas are in hard material so plasticity should not be a problem, though water may be. Usually our blast holes are dry but if we are trying to drill two or three benches for grade control this may not be the case. I guess this will be determined by how much air we have onboard the rig.

Helena Russell
1 year ago
Helena Russell 1 year ago

I agree that a rotary cone is a good way to go. If you are interested, there are a couple of good papers downloadable from the AusIMM that show results of testing for bias between tiered riffle splitters and cones; make sure the splitter is able to rotated in all directions so it can hang exactly vertical. Also that the height can be adjusted for easy access for cleaning and ergonomics for the samplers/offsiders!

Jean Rasczak
1 year ago
Jean Rasczak 1 year ago

Currently use rotating cone for sample collection onsite, wouldn't even dream of using riffle splitters. Two points make sure the setup is level; you will find the sandvik system fitted has a spirit bubble to ensure its level. 2kg sample is a bit lite, I would be aiming for at least 3-4kgs.

Unterstarm
1 year ago
Unterstarm 1 year ago

It is encouraging to see you coming over to the RC sampling world! If you are looking for information to do the RC conversion we will be happy to help in any way we can. Drillstar has many RC conversions as standard, see http://is.gd/Wh6SRz for information. If you are looking for information on the sampling side of it have a read of http://is.gd/Xux8qG, he was the designer of the Sandvik Sampling system and his new system is a big improvement to the RC sampling world. Particularly, if you are interested in 100% recovery, as there is no other system on the market which has this feature.

Sugar Watkins
1 year ago
Sugar Watkins 1 year ago

Happy to hear you are in a position to make some positive changes to your sampling application with RC.

I designed the Sandvik Sampling System with the RotaPort Cone Splitter back in 2004 when we were UDR (prior to Sandvik acquisition). Before that, I worked for Metal Craft (later SDS Metal Craft) where we pioneered the original cone splitter concept and the paper that rightly mentions (Cone v Riffle) was published by Anglo Gold based on testwork at Sunrise Dam with this cone splitter and one of our riffles.

The UDR RotaPort Cone Splitter was developed as a result of the Anglo Gold tests where stationary cone splitters suffered significant bias if the system wasn't levelled correctly or the feed flow was compromised. Rotating the ports picked up any flow bias per revolution and thus significantly improved representivity as has been suggested by the other posts in this discussion.

However, like everything, there is always room for refinements and further improvements. The RotaPort Cone Splitter, like all cone splitters, relies on the "hour glass effect" to function correctly. That is, much like an hour glass a minimum volume of cuttings must first be collected before being released into the throat of the cone splitter to prevent flow bias down one side, i.e. if say a mere handful of cuttings were dropped into the throat the volume would be so small it would simply fall through the splitter on one side without creating any hour glass effect, the splitter would have no ability to homogenise the sample and it would cause significant bias. It is therefore critical to collect about 1m worth of the interval before dumping to allow the splitter to achieve representivity. The problem with this is that the driller has no way of monitoring the condition of the bulk sample between dumping and often drilling conditions change from dry to wet, as you know. When they do the bulk mass can compact into one lump in the collection box and blockages can occur.

Our latest system, the Progradex Sampling System, overcomes this issue by homogenising the sample prior to splitting. It is a totally new concept that does not use a cone splitter (or any kind of traditional splitter) and does not therefore rely on the hour glass effect to function correctly. Furthermore, it puts between 120 to 300 complete cross sectional slices of the drilling interval per metre in the sample bag - that is a complete cross section of the interval every 3 to 8mm making it by far the most representative sample. It also offers 100% recovery for sampling (collects and samples both the coarse and fine particulate) and emits less than 10mg/m3 dust to atmosphere guaranteed. In addition, it comes with a 12 station sample bag carousel to completely remove offsiders from the drilling process during drilling, i.e. sample bags only need to be replaced during rod changes.

Other features include; sample is continuously released automatically every 10 seconds to allow constant monitoring of the condition of the drill cuttings, as a result of continuous release no more than 10 seconds worth of drilling is stored within the system at any one time, all internal faces in contact with the ore are surface treated to resist blockage, internal apertures are far larger than any other system on the market (14 times larger than a cone splitter), the height of the system is over 30% shorter than any other system, the system has the complete endorsement of Dr Francis Pitard of the World Sampling Council.

Tony Verdeschi
1 year ago
Tony Verdeschi 1 year ago

I'll be interested on how you go with this. While a great idea to RC blasthole sample my industry feedback at various attempts is that the blast crew get a bit unhappy with the slower production rate compared with conventional blast rigs - (especially when there is downtime due to sampler issues).

The new system sounds great but have you any stats on production rates compared to conventional systems in terms of drill-metres per hour in hard rock? Any information as to the availability of the sampling system in production would also be of interest.

Sugar Watkins
1 year ago
Sugar Watkins 1 year ago

My reading of your application is that with their new contractor they have the ability to drill RC for resource definition/grade control (multi bench drilling) while converting the rig back to conventional hammers to drill the blast holes. This would be my recommendation and is easily achievable if the rig is RC capable. Can you please clarify this?

Helena Russell
1 year ago
Helena Russell 1 year ago

I'm not sure why you would think that drill-m per hour in hard rock would be affected by the sample system; surely penetration rate depends on the rock mass, air pressure, and the drillers technique i.e. torque, rotation speed, hammer strike rate etc? On my last job we used a ROC L8 that could switch between face-sampling hammer for RC grade control and conventional for blast hole. Penetration rate was the same, but the overall daily production when grade control drilling was slower, owing to the time taken to position the rig for correct azimuth and dip, and to ensure correct sampling, cleaning the splitter and so on.

Gruppen
1 year ago
Gruppen 1 year ago

You are correct, we will continue to use conventional blast hole rigs for most of the work. The downhole hammer rig would be used in waste drilling a larger hole diameter to allow pattern expansion and longer hole pre-splits. However having such a rig on site, which can be easily converted to RC, gives us the opportunity to use it for grade control work. The whole concept is a bit of a trial as we have to show that the advantages for blast expansion and the pre-split capability also work and that we can effectively schedule the work phases. I am hopeful that apart from the improved sample quality the use of the system will improve our ore scheduling and have some flow-on benefits in the mill. As you know we produce a variety of products so getting the right ore at the right time can be a challenge. Interesting times as they say.

Thanks to all for the comments so far. You have given me a couple of things to follow up.

OberstGruppen
1 year ago
OberstGruppen 1 year ago

Another thing to keep in mind is the larger diameter holes and wider blasting pattern may have its own problems. It's definitely worth a trial to make sure your achieving adequate breakage. I have gone down this path before and the RC rig ends up purely being used for GC purposes (which is not a bad thing). Although having a multipurpose rig being more utilized makes for easier justifications.

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