Dry and Wet Screening in Mining: What are the Differences?
| February 14th, 2018
If you think the differences between dry and wet screen mining are limited to the presence or lack of water, then you’re missing several important points. First of all, wet separation technology requires additional equipment, including the spray nozzles that funnel the water. Extra plant capital is on the agenda when these additional stages enter the equipment line. Fend off expenditure overheads by knowing the differences between dry and wet screening.
Wet Screening Advantages
The screening decks are using vibrational energy to separate precious minerals. There are chunks of dirt and clay on the deck bottom. Some of these aperture-clogging chunks cannot pass through the screens, no matter how much oscillating motion is applied. Wet screening systems add water to the mix. Granted, the additional pipes and spray nozzles cost more than a dry screening system, but that cost is quickly accounted for as the clay is washed away. Incidentally, dry screening lines produce large clouds of floating dust. A water separation system does not allow dust to fry flee and choke the equipment.
The Benefits of Dry Screen Processing
More economical by design, standard screening solutions rely on vibrational energy and gravity. If the high-volume aggregate goes up, its mass will inevitably bring the fine grains down again. Energetic impacts separate the material so that it can be sized and sorted. Two deck models augment the process while keeping the cost of the equipment range manageable. Meanwhile, the wet “slurry” produced by the sprinkler nozzles necessitates a dewatering stage. Having said that, there comes a point when dry screening is no longer viable. For example, powdered coal requires a wet screening stage. Otherwise, the overly fine black dust would escape the screening equipment.
Weighing Different Applications
Material slurries enter different screening solutions while dry screening mechanisms tend to stick to the tried and true flat deck configuration. Cyclonic scrubbers and spiral mechanisms bend to the will of the slurry stream. As the watery stream circulates, centrifugal force splits the water from the finely ground mineral aggregate. Fortunately, urethane screens, equipped with apertures that are as small as 75-Microns, are available. They sort the finest powders as they lay suspended in the fluid medium. Left to screen coarser ore currents, the dry screening method is still the more economical solution.
Adding a series of nozzles and pipes, fluid separation plants are more costly, but that cost is warranted, for its recovered as the clay and mud deposits dissolve. Plan for pumps, discharge lines, and an environmental study when a wet screen method is adopted. Sticking to dry screening, the processing costs are lower, but now the environmental risks are confined by the mine, trapped as a cloud of dust.