There is no such thing as bad weather, however, there is such a thing as inappropriate clothing. Crushing in the winter is tougher but doesn’t have to be miserable with some planning and solid thinking.
Here are a few tips for getting your spread ready for winter crushing:
Although low temperatures rarely have a harmful effect on rubber compounds, stiffening of the belt may cause tracing problems until it warms up. This mostly applies to belts containing neoprene compounds. Before these belts will train properly, they must be warmed to a temperature above freezing.
Frost, snow and ice can also hinder proper belt performance by causing load slippage. Ice buildup on the troughed side of the belt can plug the chutes, and ice can form on the conveyor hardware and cause more damage than just material buildup.
A recommended method for “de-icing” or removing cold weather glazing is to use ethylene glycol. Calcium chloride solutions are also sometimes used, but they can corrode conveyor parts.
Ideally, ice buildup should be removed before the conveyor is started. If the system must be kept ice-free at all times, the hopper should be covered and heated if possible.
The general effects of cold on conveyor systems are: increased power demands during startup, freezing up of rotating mechanical parts and causing drive motors to stall.
An option when running a conveyor in extremely cold conditions is to never shut the conveyor down. This can be done by either running the belt at full speed or by using a creeper drive on the system.
A concern for operators is when temperatures hover around freezing – melting and freezing can occur in these conditions causes wet or sticky material to adhere to screens and conveyors throughout the day. That material will then freeze into place overnight and create problems the next day. Operators have some very effective tools at their disposal to address these kinds of problems.
SELF-CLEANING SCREEN MEDIA
For screening, engineered self-clean media is now available to keep blinding to a minimum and provide effective dry separation of fine sizes, even in marginal weather conditions.
BELTS AND BELT SCRAPERS
Keeping conveyor belts clean and moving is the primary challenge in the winter. There is a wide range of belt scrapers and brushes available which can keep belts clean and moving. An important consideration for portable plants is that conveyor tail pulleys are mounted low to the ground. This means the belt must be kept clean to prevent material from collecting on the underside of the belt which can mis-track the belt or harm pulley bearings. If maintained properly, belt scrapers can eliminate a lot of conveyor build-up problems. Always ensure skirting rubber and plow scraper are not frozen to the belt before starting the conveyor. Also, make sure you switch to using synthetic oil in the gearboxes for your conveyors.
There are several varieties, sizes and models of conveyor belt heaters which have been developed for severe cold and winter conditions. Some are designed specifically to apply the right amount of heat to areas where ice buildup occurs, such as drive rolls, bend pulleys and idlers. The unit is placed close to the driver roll or bend pulley in order to heat and dry the bell as well as the roll. This goes a long way to reducing or eliminating ice accumulation where it is most likely to occur.
Another benefit of using belt heaters is they de-ice the belt and prevent material slide back and problems with the belt scrapers. Eliminating ice on a drive roll to prevent drive roll slippage can also eliminate the need for increased belt tension, meaning there will be less belt wear and less horsepower required.
CONES & JAWS
If you are shutting down the plant for a night or a weekend, it is a good idea to cover the jaw or cone with a tarp to keep snow from accumulating on it. You also need to switch to synthetic oil for cones, and change grease everywhere from EP1 to EP2 which has a lower freezing point. If you can, run two shifts a day instead of one to keep everything warm and moving.
CRITICAL HYDRAULIC LINES
Wrap in Heat Tape. Pay special attention to your cone accumulator line.
One of the few advantages of winter operating is improved screening efficiency, provided the weather stays cold and clear. In sub-zero temperatures, there is no free water available to bind particles together, allowing fine sized particles (including piggyback fines on larger material) to more easily separate from larger particles. The result is improvement screen output and finished product cleanliness.
Successful winter crushing demands the right maintenance processes and accessories.
For more information about getting ready for winter, contact us!