Collin Jackson, president of BM&M Screening Solutions, explains the consequences of not properly cleaning grain. “Grain cleaning becomes an insurance policy because there are huge costs associated with improper cleaning. Not taking this value-adding step could lead directly to the rejection of an entire shipment. It only takes a miniscule percentage to deem the product off-spec,” Jackson says.
Reaching those specifications can only be achieved through first inspecting and understanding what type of foreign matter you’re trying to remove.
Devising a system
Grain cleaning often employs the use of multiple machines and technologies. Each of the different components is more or less organs in the grain cleaning body. It starts with screening and is done in large quantities, but as it progresses, grain is cleaned in smaller batches and requires scalpers, rotary cleaners and aspirators. Matt Ernst, vice president of Carter Day International says most of his customers require a variety of products to reach their specs. “We end up putting in multiple machines to address all the materials they need to get out, things like scalping and aspiration in a preclean stage, sifting in a flat screen later down the road. It’s a complete system that you’re developing; it’s not just one magic screener,” says Ernst.
But before determining which products to use and when, the dockage must be determined. Most grain cleaning equipment manufacturers offer dockage testing to their customers and analyze the material for them. The dockage test sorts out all of the material in the batch based on size, length and width and then gives a clear visual sample of what is in the mix.
Ernst suggests that the grain elevator operator take an active role in determining their dockage as well. “They should be taking samples and analyzing the foreign material in their grain over the year, and they can use a dockage tester or hand sifter to examine the materials,” Ernst says. “A lot of customers are using a system that is not developed for their needs, which can be avoided by simply inspecting what your foreign matter is on a regular basis,” he adds.
Once the type of dockage is determined, you need to identify its physical characteristics. Grain cleaning is essentially a process of separating pieces based on differences in physical characteristics, and machines are built to allow only certain properties through the screens. Grain cleaning machines can separate based on size, density/weight, length or width/thickness. Most machines can only differentiate based on one of these characteristics at a time, which is why a tailored cleaning system is the most effective method.
Bob Knoedler, division manager of Screening Strategies, a division of Triple/S, asks his customers a series of questions to tailor the right cleaning system for the job. “We’re going to ask them how many bushels per hour they process, what their dockage specifications are and what’s in the grain to begin with,” Knoedler says. “Some are concerned with cobs, and others just want the fines and the brokens out.”
Capacity is arguably the second most important piece of the grain cleaning puzzle. With today’s high grain prices and competitive market, contract grain cleaners and elevators strive to clean as much grain as they can as fast as they can on a 24-7 basis. Jackson recognizes this as a huge burden on the industry. “The No. 1 problem is their desire to increase capacity due to economic need or greed. Everyone wants to run as much as they can and they do, but it only decreases the effectiveness of their system,” Jackson says.
In order to run an efficient grain cleaning operation, staying within the capacity parameters is a must. The proper capacity is determined by each individual piece of equipment and can vary from 10 tons/hour to more 400 tons/hour. Running machines over capacity means less of the foreign material will be removed from the grain. “It used to be 1% to 2% foreign material was acceptable, but now exporters must keep it at around 0.3% – 1%, depending on the grain being handled,” Jackson says. It’s not worth it to risk rejection in order to clean a higher capacity.