Yair . . . I'm just curious as to the applications of cable shovels versus the big hydraulics that are coming in. A bit of a discussion on the pros and cons and why you would use one in preference to the other may be of interest to others who like me who have never even seen one of the hydraulic machines. Thanks and Cheers.
Lots of reasons I guess, some of which would be: - 1. Availability of power. At the size we're talking about a cable shovel works on a 6,600-volt trailing cable and uses mega amounts of power. Some mines just do not have an electrical system that can cope with that so you go for a diesel-driven machine which is these days a hydraulic machine. 2. Projected mine life. A cable shovel can literally be rebuilt ad infinitum. Usually when they are bought new they have a projected life of at least 20-25 years. In contrast a hydraulic shovel is normally given a life of 7-10 years. The relative purchase prices of a cable shovel versus a hydraulic machine of a similar size reflect this. If you were starting a new mine that will be worked out in less than 20 years (whether you had electrical power or not as per 1 above) would you consider a cable shovel..? Probably not because you wouldn't get value for money from your purchase. 3. Mobility. A cable shovel's usually a good dealer heavier and therefore less mobile than a hydraulic shovel. If your mine plan requires "selective mining" and shovels moving every which way on a regular basis you probably wouldn't buy a cable shovel. We went hydraulic because we hadn't got enough electrical power available, plus because of our mining plan we needed more mobility than a cable shovel could provide.
Any opinions on the new P&H hybrid? http://www.phmining.com/en/PHMining/Mining-Equipment/HybridShovels.htm
Diesel engines, hydraulics, & high-voltage electricity don't mix in a confined space like that IMHO. Anyone like me who remembers less than fondly the Marion 183M which was basically a 1960's-70's version of this new P&H product (but without the hydraulics it has to be said) will shudder at the thought .............
Yair . . . Thanks Nige I have to say I did not realise all "current" cable machines were electric powered . . . I was more curious as to the pros and cons of the hydraulic versus mechanical digging arrangement and how cable stacks up price-wise against oil from a maintainance point of view. Cheers
Hey Scrub, I'm on my phone heading in for my last nightshift of the cycle, so I'll reply when I get home tomorrow and don't have to type it all out on my phone.
Scrub, I know its not a big shovel, but when we used to run a 6.5 yd 180D northwest, there wasn't a hydraulic face shovel that could touch it in terms of production in hard digging. Mind you this was in the earlier days of hydraulics and we were comparing to a 245 cat and ex 750 or so sized hitachi. Even those smaller machines couldn't touch the cycle times. Cost per ton was lower with the northwest until its age caught up with it. We ended up retiring The northwest when the engine we had rebuilt burnt in a shop fire. We switched to an ex1000 in excavator configuration.
Yair . . . Thanks fellers. Interesting stuff. Cheers.
OK, lets see if I can type this out without rambling on.........just came off nightshifts. Nige covered a good portion of it, I would like to say though, that with the voltages run on the rope shovels vary quite a bit depending on power available, and global location. When run on 60 Hz power supplies, typical voltage is usually 4160V, 7200V, or 13800V. When run on 50 Hz power supplies, they most common voltages are 6000V, 6600V, 7200V or 11000V. So like Nige mentions, available power may play a very large part in making a decision on what to buy. There is more than one example of a mine setting up generating capability to support shovels and the process plant, but it's not always an economically viable measure if the mine has a short projected lifespan. When it comes to pros and cons of rope vs hydraulic shovels, there are may varied views. With so many variables, it's really hard to say with any degree of conviction, that one or the other will excel without having a set of parameters to follow for a specific mine. Generally, for electric rope shovels, the pros are a lower operating cost, longer service life, higher production, lower maintenance costs, and higher bench heights during mining. The cons are usually, reduced mobility, need for a substantial and stable power supply, a larger and more specialized support staff and tooling, more infrastructure around the mine, higher initial purchase costs, a need for support equipment for the shovels, much more difficult to move from job to job, or mine to mine, and less selective digging ability. For Hydraulics, the pros can be higher mobility, lower initial purchase costs, lower requirements for mine infrastructure, no need for a separate power supply, more selective digging capability, fewer specialized workers, less dependance on support equipment, machines that are quite easy to move from mine to mine, or job to job as the case may be, and a greater variety of machines and machine sizes available. The cons can be higher operating costs, more maintenance intensive machines, shorter service life, less productive in the grand scheme of things, typically smaller machine classes available....though the latest machines are challenging that, generally a more mechanically complex machine, with lower availability, and shorter service life. Typically, if you have a mine that has a projected life of less than 10 years, hydraulic or wheel loaders may be the way to go. However, if the mine life is projected in excess of 15 years, you begin to move into the realm of rope shovels. With small, short duration mines, a hydraulic is the way to go. Not that a rope shovel wouldn't be a good machine, but it's more difficult to find decent rope shovels used and not worn out old junkers. Buying new would drive the costs up of the mining operation, possibly beyond what is economically feasible. You just won't be able to get the value out of a new rope shovel with a short lifespan mine, but a hydraulic excavator is perfectly suited for a short duration project. Production rates and truck size will also help to dictate what type of shovel you want. If you are running smaller trucks, the generally smaller hydraulic shovels will typically be better suited. However, if you project high production rates, with ultra class trucks, a rope machine will likely be the better choice. Type of face, mine design and bench height will also play into the choice. High benches, bulk digging, and large pits where the shovels will be able to stay put and dig will push you towards rope shovels. But if your design dictates low face height, frequent changes of location, and mixing or blending ore or material, or selective mining, a hydraulic shovel will be a more flexible choice for you. With the introduction of the P&H 2650CX and the Cat 6120B H FS, the bar has been raised. But since there are no machines in the dirt yet, and likely won't be for quite some time, it remains to be seen how well they will work out in the real world. Hydraulics will all leak at some point, some more than others, but they will all leak a bit anyhow. Leaking oil and electric motors are not a great combination usually, since it's not always a great idea to steam clean an electric motor, and cleaning up oil leaks by hand is a bit time consuming, and not really practical. This is one of the reasons Bucyrus located the hydraulics for their Hydra Crowd outside of the house on the 495 shovels. This has been a problematic system so far for those who operate them, but it is improving. Of the two choices I mentioned above, I would favour the P&H due to it's minimal hydraulic dependance. However, since no machine has been built yet, it could be a complete bust.....only time will tell. Based on the first hand experience I have with Bucyrus electric shovels, I'm not sure the 6120 will perform as some hope it will. Though, they do have the knowledge pool of O&K to draw off of. I just don't know how much input the hydraulic gurus will or have really had. As for digging with a rope shovel vs. a hydraulic shovel, they both have applications where they excel. A hydraulic shovel is more selective as has been stated, it also has the ability to pry tight material out of the face, or floor. A rope shovel has no real ability to pry against tight material. This is part of the reason P&H is developing the hydraulic clam on the 2650 CX. The ability to rotate the bucket and selectively pick at a hard spot in the face, or toe will allow for this prying movement. A hydraulic shovel is also most effective usually when benching the face. That is, digging a series of benches as deep as it can reach into the face, as it digs down to the floor in order to minimize the force needed to break out the material. Rope shovels are also capable of benching to a certain degree, but far less so than hydraulics are. The new 2650 CX from P&H will be able to bench with a bucket that can be rotated to allow a straight push into the face to fill it, then rotated back to carry the material.....much like a wheel loader. This is a feature that has been pretty much the domain of hydraulic shovels.....with a few notable exceptions like the Marion Super Front. Price wise, rope shovels are generally more expensive to purchase initially, but have a lower operating cost per ton over their life time. A longer lifespan, means longer time to payback the initial cost, as well as lower maintenance costs and higher production can mean a significant savings over time. Hydraulic shovels have a lower initial purchase price, but require more intensive maintenance, more frequently, and have a lower production rate as a general rule. As I have said however, every circumstance is different, so many different factors can change almost any of the variables enough, to sway a decision in the other direction. I honestly feel a fleet of rope shovels, with hydraulic shovels as support and backup machines give you the most bang for your buck. Apparently, the people making the decisions at work feel differently however, as our hydraulic fleet is slowly shrinking. At any rate, I know I missed lots of what I wanted to say, so ask all the questions you can, and I'll try and fill in the blanks as best I can.
Yair . . . alco Thanks for the detailed response. The detailed knowlege on this site is amazing. Thanks for sharing. Cheers.