The nice, sweet, clean deposits are gone – and the potential of double (or even triple) washing is here to stay. “That’s a frustrating issue for most producers as they face today’s tough deposits. There’s still value in that deposit – but it just takes more processing time and equipment to get the good stuff out,” says Lauren DeBow, washing applications engineer for Superior Industries. DeBow and her team assist producers with thorough applications analysis and custom wash plant solutions.
When “digging into” the dirtiest deposits, DeBow opts for focus over frustration. The focus is finding the lowest costs per ton while meeting required specifications. “Washing is a unique process for each and every operation. Developing wash plant cost-efficiency depends upon the particular deposit, specification and capacity requirements, and overall plant operations – so we focus on each unique parameter,” DeBow stresses – as she shares the following tips on maneuvering material processing when double washing is required.
First, there are limits to any single piece of washing equipment – whether it’s a sand screw, a classifying tank, or even a cyclone. In washing, there are no “one-size-fits-all” equipment solutions.
“Sure, some pieces of equipment are more efficient than others, but everything has its place,” she says. Secondly, when operations have more than 12-percent minus #200-mesh (fines) in the feed material, there are too many fines to be washed out in one pass.
Consider that with DOT #C33 sand products being in such high demand throughout the country, more producers are realizing just what it takes to meet washing requirements. For example, a single sand screw or a single cyclone cannot make a common C33 sand out of feed material that is at or above the 12-percent minus #200-mesh threshold.
To explain further, a C33 spec sand typically limits material passing #200 mesh to between zero and 3-percent - a very tight and limiting bottom end.
Consequently, if it’s common for feed material to contain a fines percentage ranging from 12-percent, and all the way up to 30-percent more work, more equipment, more water, and more washing is required to meet product specifications.
Frustrations with dirty deposits are understandable but focus on the solutions instead. Industry experts are ready to help. DeBow says she finds it fascinating, and even fun, to assist operations with double washing – as she says there’s so many ways to tackle it. “With Superior’s complete equipment toolbox, we provide producers with custom solutions that fit the site, the deposit, the feed, the final products, and the budget,” she says.
Solutions vary widely, from simple to more sophisticated. According to DeBow,
“When dealing with a low to moderate fines percentage, it may be just a matter of adding another sand screw. Or it’s as easy as adding a dewatering screen with spray bars just to get the bottom end tightened up a bit.”
When the feed material approaches 20-percent of material passing #200 mesh, some operations combine cyclones with sand screws for greater control. Also, many solutions involve the use of a classifying tank followed by a sand screw. The classifier filters off a substantial portion of the minus #200-mesh in the first pass, while the remainder is processed again as it hits the sand screw.
In some cases, it’s best to place a cyclone ahead of a classifying tank. As the cyclone pulls off a portion of the #200’s, it takes some of the pressure off the classifying tank, allowing the producer to use a smaller classifier for cost savings or space restrictions.
Again, each wet processing operation is different, and each custom solution depends upon specific parameters and proper analysis. No matter how tough the application is, cost-efficient washing remains within reach.
Don’t get frustrated, get focused.