Ah right .. So what Shovel (pound for pound) is Best for the hard stuff up at the sands?
Sorry, I must have missed this post.
In really hard digging, the RH400s blow everything else away with the ability to vary the digging angles and actually pry the material out of the bank. Other hydraulics are very good at this as well, but the 400 has the most power for hard material.
In average to moderately hard digging, the P&H 4100s really seem to excel.
In overburden/topcut where the digging is fairly easy, the BI 495s seem to do quite well. The main issue with them is how poorly they handle hard digging. They have a tendency to shake themselves to death when the going gets tough, but are pretty quick and powerful when they aren't struggling against hard material.
The 4100C BOSS we have is a DC drive machine, and it is one of the most impressive machines I have seen yet. I do wonder, however, what the new 4100C BOSS AC machine we have coming this year will prove to be like.
HRKTechnik,
There could be many answers to the questions you pose. These answers will depend on the type of material the shovel is digging, the type of shovel, the way the shovel is spec'd out, the model of shovel and so on.
I'll try to answer what I can of the questions, but please remember, there are no hard and fast rules that dictate every situation.
Example: a shovel digs until no sufficient material is in its reach, so it has to move forward using its crawlers. How many meters does it move towards the face to start digging the next section or "slice" of the block, i.e. how thick is that "slice" a shovel can dig between two moves?
The reach the shovel has will generally determine the amount of material it removes before it makes a move further into the cut. This however can be influenced by whether the material is blasted or not. With blasted material, it is more likely to slough down and bring the toe in closer to the shovel while keeping the crest of the face further away from the point sheaves and boom. With unblasted material, the face tends to stand in a more vertical manner, which means the machine cannot move forward as far because the crest of the face will be in too close to work if it does. Since machines can be spec'd out with different boom and stick lengths, and different models have different reaches, it's not really possible to determine an actual number without using a specific prototype spec to work from. In our operations, we have material that sloughs, material that stands vertical or actually undercuts, and in very, very rare circumstances, material that gets blasted. I've seen faces where the point sheaves are (we'll say almost) brushing the top of the face and the bucket cannot even reach the face to get another bucket. I know that should never happen, but sometimes it does.
How long does that moving forward take?
That would depend on the type of shovel mostly, but would still be fairly easy to give a rough number. A hydraulic shovel will take only a couple of seconds to move forward since they can simply walk forward as needed, when needed. We could estimate a hydraulic shovel would take 3 to 5 seconds to move forward. It may take less, but that would be a rough number. Now, a cable machine takes far more time. Before they can move, they have to set their brakes, transfer from dig to propel, release brakes, then move forward. Once they have moved the distance they want, they have to set their brakes, transfer from propel to dig, and them release their brakes again. Depending on the make and model of shovel, this can take anywhere from probably 20 to 30 seconds.
what is a common block width and length, bench height?[/ QUOTE]
Depending on how the mine is laid out and the material being moved, this can vary dramatically. In our mine, we don't have a rigid block system since the material we move dips and varies greatly in thickness and angle. In some mines, things are laid out in a rigid pattern, but I haven't experienced it, so I can't give you and answer on that part. Bench height depends on the thickness of the material, the size of the shovel and the style of mining used. We tend to have seams of material that vary from one meter to about 25 meters in thickness. Our typical rule is that the bucket teeth must be able to break through the upper crust of the face and therefore the bench height must be about one meter lower than the maximum height that the shovel teeth can reach. If we have a band of material that is higher than this, we tend to use dozers to push the material down to at least that height or less. For hydraulic shovels we try not to set them in faces that are higher than the top of the cab. This is in case the face sloughs since you work so much closer to the face with a hydraulic than with a cable machine.
how often is dual side loading possible?
In most cases, it is almost always available if the pit is set up with cable stands to let the trucks get to both sides of the cable on a cable machine. Other than that, the only real limiting factor is being in a corner where you only have room for a truck on one side. An estimate is about 85 percent of the time, loading both sides is possible.
what times do you have on a shovel through which it isn't digging, although technically it could (e.g. because you eat, drink or take a p..., make a transfer at start and end of shift etc.)?
Depending again on all sorts of different factors, shovels tend to run as much a possible. We switch our operators out for lunch, so the only real delay would be to get up for an unplanned washroom break, and to switch operators. I've never timed it, but I would guess switching operators would be around 5 mins and washroom breaks would be less than a minute.
We rarely blast, only when the material gets to hard to dig. So I can't answer any of the blasting questions for you.
