A large-scale manufacturer of resin sand mixers, facing concerns over the efficiency and environmental impact of its equipment, turned to global dosing pump specialist SEKO for a multi-purpose solution.
Within the foundry industry, resin-coated sand has for many years been a popular material for iron casting moulds as it is easily compacted and provides a smooth, consistent and defect-free surface to the finished product.
Resin sand is considered among the best moulding sands for the casting of steel, cast iron and non-ferrous metals, including automotive parts such as pumps, motors and engine blocks.
Resin moulding sand is produced by dosing one or more binder chemicals – including furan resin – into crude sand before mixing and pouring the material into casts to harden, ready for the product pattern to be imprinted.
Benzene, toluene and xylenes
A major drawback of this process is that when furan resin is thermally decomposed during metal casting, air pollutants such as benzene, toluene and xylenes are produced which, if not closely controlled, can have a significant effect on the environment along with the health of workers and local residents.
Consequently, the perception of resin sand mixers within the foundry industry is becoming increasingly negative, and our client – a major producer of these machines – was concerned that unless the process could be improved, take-up of the product might reduce to the extent that it would eventually be eliminated from the casting industry entirely.
Looking to reduce the polluting impact of its sand mixers without compromising their performance, the client approached world-leading chemical dosing pump specialist SEKO to deliver a solution.
SEKO’s technical team carried out a comprehensive assessment of the client’s system and discovered that the existing process dosed furan resin and benzenesulfonic acid into the crude sand via a gear pump which, while providing high output, was considerably lacking in accuracy. This inevitably caused excessive chemical dosing which, as well as causing costly wastage, exacerbated the emission of polluting gases. In addition, the existing equipment was noisy, caused large flow and pressure pulsations and had a high maintenance requirement.
Taking into account the client’s specific process requirements along with the nature of the additives being pumped, the SEKO technical team recommended the Spring MS1 mechanical diaphragm dosing pump for an accurate, reliable and cost-effective alternative to gear pumps.
The Spring MS1’s analogue-controlled dosing accuracy meant that the binders could be metered in proportion to the volume of crude sand, resulting in a consistent mix while minimising chemical wastage. Meanwhile, the pump’s high-grade PTFE diaphragms and PVC/PVDF head – known for their superior chemical compatibility – were considered ideal for handling the aggressive benzenesulfonic acid and helping to ensure the pump’s reliable, long-life performance.
The Spring MS1, with its zero-leakage profile and impressive low failure rate, is proven to be capable of continuous dosing. This is in part due to an intelligent ball valve design which allows the component to be easily removed for cleaning without the need for regular shutdown maintenance – a direct improvement on the client’s existing equipment.
As well as an improvement in the overall dosing performance of the resin sand mixer, the client has seen a significant reduction in the emission of pollutants, allowing them to protect workers and neighbours while reassuring existing and prospective customers that their product is environmentally responsible.
Along with the treatment of moulding sand, the versatile Spring MS1 is suited to machines in applications as varied as agriculture, food and beverage and power generation, meaning OEMs can fit it to a wide range of products requiring a similar level of dosing accuracy.
seko.com
