Gems of Advice Marion Machine Spotlight On: Secondary Crushing – Preventative Maintenance!

Preventative maintenance prevents downtime

If you read my last Blog, then you may remember we left off talking about the primary. So, now we will continue moving through the flow of material from our primary on down the process. We should now turn our attention to “the secondary.” As I am sure you already know, this aspect of production is every bit as critical as that of the primary crusher… maybe even more so. This is why it is much more important that you are familiar with the “ins and outs” of the secondary system. The secondary is vitally important to about 98% of quarry applications- the exception being if you belong to a Rip Rap/Surge based operation. If you have more than a pile of rip rap on your mine site then pull up a seat, because this one is for you!

After your material leaves your primary and enters your surge pile- the real fun begins! From the surge pile to your feeders, from your scalping/sizing screen all the way into your standard crusher… these “pieces of the puzzle” that make up your plant all rely on each other to create a successful day of crushing. These pieces create a big picture for your plant, and it is crucial that you keep a close eye on all of them. By doing so, you can ensure your plant is producing at its optimum capacity to meet the needs of operation. There are many steps one should take to ensure a plant is fine-tuned and running the way it needs to – it is an important responsibility of plant operators to ensure maintenance and surveillance is happening at all levels of operation. But with that being said we are not going to talk about the secondary crushers, screens, or anything else – instead, we are talking about the supply lines of every plant – The Conveyors!

Without conveyors, we would all be stuck with a big pile of materials and no functioning plant. I imagine something like the Bedrock Quarry in the Flintstones… workers with hammers and piles of stone, loading their hauls on to dinosaurs for transport. We definitely don’t want to go back to working in the stone ages! To ensure our belts are in their best shape, there are a few steps that should be taken to ensure that none of us ever have to see a “rip and drop”

Check out your equipment every day

Daily Inspections – these are to helpful in spotting any brewing issues before we end up spending an all-nighter using flexcos to “splice” a belt to make it useable the next day. I recommend walking your belts daily- even multiple times daily to look for anything concerning. By walking our conveyors, we can become more familiar with them- and thus can more easily spot an issue, or hopefully potential issue, before a bigger problem arises. When looking at your conveyor belts specifically, I recommend the following:

• Look for “snags” or small tears along the edge of the belt. It’s incredibly easy for this minor issue to cause a belt to track into the frame and create a rough edge. Within just a few days, a rough edge can easily cause a tear. This “should” never happen- if an operator sees a belt track into the structure, actions should be taken immediately to correct or “train” the belt back into position. Many times before I have seen“old hands”- or a seasoned miner use a sharp knife to trim a snag into a smooth transition back into the belt. This helps eliminate a point where a more extensive tear could start. This is not ideal, and should only really be done when there is no alternative- but if a snag is left, it will find an unforgiving edge and end as a tear- usually sooner rather than later. Something as simple as a belt tracking off to one side can cause a snag to become a much bigger problem. I have personally witnessed a snag that was not addressed catch an I-beam and rip almost half way through a conveyor belt. Luckily, we were on the ground watching the belt due to a tracking issue and were able to stop the belt before it made another round back to the snag… or it could have been a much worse day.
• Look for dry rot– or for a belt being too worn to stay in production. Sun bleaching will cause this over time, and so will the nature of the conveyor itself and the work that it does. Wear and tear of the media the belt is made out of happens every time a belt rolls over a conveyor, impact bed, or roller, and contributes to fatigue of the belt itself. Each belt has a lifespan- there will always come a time where it is more appropriate to “cut your losses” and purchase a new belt. Much like the tires on a vehicle that is driven daily- even tires with perfectly fine tread may need to be discarded due to dry rot that makes them unsafe to operate on the road. Same can occur with conveyor belt media- sometimes a judgement call has to be made as to whether the belt needs to be replaced. Not only could this lead to a rip and tear in the belt, and therefore a halt in production, but worse- this is a true safety concern. I have traveled to plants and found conveyors that should have long been replaced- their rich black color replaced with an ashy gray- and wondered to myself how many more passes that belt could take before it ripped… and then prayed that no one would be underneath it when it did.
• Look at your rollers –far too often attention is placed on head, tail, and breakover pulleys while the rollers are ignored. If you have ever worked on the ground in a rock quarry, you know one thing pulleys have that rollers do not- grease fittings. Rollers are typically a sealed bearing system that can work great for many years… but like everything else in a quarry, the bearings will eventually fail- and when they do, that “can” will stop rolling. When that happens, it doesn’t take long for the thin metal body of the roller to be eaten away and develop a razor sharp edge- with rubber continuously sliding over it. You can imagine that this creates a “ticking time bomb” for a bad situation to develop. Watch those rollers! Thankfully it is really easy to spot a non-functioning roller… if it’s not rolling, it’s time for it to be addressed. Adding a bonus piece of advice when it comes to a roller- use extreme caution when changing them out! Remember that they can be razor sharp…and take it from me personally, that is a lesson best not learned the hard way. Note as well that once a hole has been worn in to a roller, they like to hold material. This can make them extremely heavy and hard to manage when changing them out. Do this very carefully!
• Check your guards! This should be self explanatory, but lets dive in a little deeper. Guards should be substantial and robust- enough to prevent any accidental contact. Unfortunately, a lot of us have seen guards being held in place by zip ties (and a prayer that an MSHA inspector doesn’t show up until that metal gets welded back in place). How many times have we all witnessed a guard at the head pulley so full of material that it pushes the expanded metal out? I have also observed guards with grease hoses tied to them- and gobs of grease piled up on the catwalk below where a groundman wasn’t paying attention. Unfortunately, sometimes these messes are not addressed ASAP and can lead to bigger issues. Take time while walking your conveyors to address these issues before they become big problems! I also recommend taking time during conveyor walks to look at your return roller guards. You can easily miss the amount of material being help up on that thin expanded metal- and it’s even worse to try and remove this without help. Another personal mistake made when I was much younger and “all brawn with no brain”. Take time to clean those guards out. Lock out, tag out, and try out your equipment… and then get those messes cleaned up! It can be as simple as a strong water hose- water can work wonders in keeping those material build-ups in check.
• It may seem obvious, but check your catwalks! Walking your plant is the perfect time to look closely at your catwalks. When I previously worked as a young ground man, I was tasked daily with walking the conveyors at my plant. One critical piece of equipment I carried while doing my walks was my trusty chipping hammer. Yes, you are reading that right. A wooden handled chipping hammer. I would carry it with me to every conveyor… and it served me well in what may be the most boring task a young man could ever take on- removing rocks from catwalk tread plates! The plant I started out in had expanded metal with kickboards, which made this a very time consuming task as well. I would use the chipping hammer to dislodge every rock that would not pass through that expanded metal. While doing this job, I learned a very valuable lesson that I still use every day in multiple facets of my career. One day, while my plant was down, a long-time truck driver came down from the dump bridge and started cleaning a catwalk that was running close to the one I was on. I noticed that every so often, he would throw a couple of rocks over and then stop and look around- at the structure, at the belt, at the rollers, at any working part that was close to him. I was curious, and after watching him for a little while I had to ask him what he was doing. He called for me to come over to see, and I walked up the conveyor to meet him. Once on the conveyor, he was able to point out a few bad rollers, and some other small issues he had spotted. He explained to me that just because I was doing one task didn’t mean I couldn’t be observing and checking for other possible trouble areas as well. He taught me value in multi-tasking, and taking the time to look for the “small things”. I learned a lot from that man, JR was his name, and I still try to utilize his lessons daily… while completing others tasks, take time to look around and check that every other facet of production happening around you is also “good-to-go”!

Grease is king!

Lube: Grease those pulleys! Grease worms are a mean beast to combat… but the best kept secret to keeping them under control is routine. Make it your standard course of action to grease your plants equipment the same way and at the same time- as often as you determine is needed. Personally, I greased my areas three times a week. I have worked at plants that would grease daily, and also observed those that would grease once a week. I have also traveled to plants where I never saw a grease gun in use… not saying they didn’t grease, just that I never observed it. Grease is the life of any bearing, and bearings are the life of pulleys. It’s a simple addition to your routine that can make a huge difference!

Drive belt inspections: Make sure to routinely check your drive belts. Simply walking by and verifying that they are all on the sheave does not constitute an inspection. To conduct a true inspection, you should “lock out, tag out, and try out”. The guard should be removed to conduct a proper inspection of your drive belt. There are several things you should be inspecting while the guard is off:

• Belt placement– seeing that all belts are accounted for and where they should be
• Sheave condition– checking to make sure the belts are not “bottoming out” in the sheave and that the top of sheave isn’t razor sharp between the belts
• Belt condition– dry rot, shredding, and excessive rubber dust can all be signs of pending failure. Take action now!
• Proper belt tension– belts that are too tight can cause as much of an issue as loose belts. You wont have to worry about slipping… but being too tight can cause other damage including premature belt failure, gear reducer issues, and even premature bearing failure

With the guards open, it is also the perfect time to check out speed reducers, clean the sight windows (if equipped), clean/change the filter (if needed), check for leaks, and generally give everything the “once over”. This is also a great time to remove any excessive material that can gather up in the guard area!

Get to know your secondary equipment

It may seem like a lot, but it is vital that you get to know your secondary equipment, and that you routinely do assessments to ensure that everything stays in optimal working order. The more familiar you are with your equipment, the easier it is to spot a potential issue and address it before it becomes a problem. While a lot of these things are not needed on a daily basis, there are some things I recommend be inspected daily- such as your conveyor belts. Belts should be walked daily and any abnormality or issue should be addressed, or at least noted immediately, so that plans can be made to fix them (if the severity allows) to prevent a disruption in production.

Routine is your friend! Find a schedule that works for you and follow it. Make it standard for your operation and take the initiative to ensure it gets done! By creating this routine, you can easily spot when things aren’t right. If we don’t know our plants and our equipment, how can we recognize an issue? I personally have seen examples of this “make or break” a plant. For example, a seasoned plant operator noticed a conveyor loading with a heavier load than normal… which lead to the recognition of the start of a bearing failure that would have gone unnoticed. His familiarity with his equipment triggered his recognition of something abnormal, and he potentially saved the plant from having a disastrous, and production halting issue.

An example of the opposite is something I witnessed and will always remember: a plant operator (fairly new) who did not take the time to observe and learn his plant. He missed several indicators of a pending bearing failure. It ended with a bearing billowing smoke and eventually locking up – and that wasn’t the end of the problem. The bearing eventually ended up building up enough heat to catch the grease inside on fire (well, at least it had grease) and drop of the grease fire started falling to the ground. Luckily, the ground man was at lunch… because the failure happened at a breakover pulley about 15-20 feet away from the spot where the welding truck / plant truck was often parked. It would have been horrifying to witness a plant induced rock quarry version of “tar and feathering”. The problem was eventually noticed (plant shut down), addressed (aka fire put out), and corrected (bearing was replaced).

While it is crucial you learn the ins-and-outs of your crushers and equipment, I can assure you that learning and familiarizing yourself with all of your secondary equipment can make all of the difference in your days production. Remember- all of your equipment, from the top to the bottom, are the “puzzle pieces” of your plants bigger picture and daily operating… and a little surveillance and maintenance can go a long way!

Good luck and have fun making little ones out of big ones!

Written by: Brandon Godman

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