Improved quality and cost savings through new process at hot-dip galvanising plant in Finland
First of a kind, fully automated flux iron removal device installed at Teknotyö Kuumasinkitys Oy
An innovative flux iron removal device was installed at Teknotyö Kuumasinkitys Oy in Järvenpää, Finland, on 2 April 2019. Measuring 2.5 x 2.5 metres, the device is a smaller version of its original marine container-sized predecessor, which consisted of two units. The new device has been built on a steel pallet, making it easy to move from one place to another. Teknotyö Kuumasinkitys Oy can therefore use the device at both of its sites in Järvenpää and Ylistaro.
The fully automated flux iron removal device is a modern version of a traditional process used in many galvanising plants across the world. The old process demanded more human resources and also brought production to a halt. The amount of ammonia needed was estimated, which easily led to lost zinc salts due to excessive pH. In addition, iron was only partially removed, leading to quality issues.
The new first of a kind device pumps the flux to the reactor from a basin. The reagents are dosed automatically according to the exact requirements. The iron sludge that is produced is then filtered and the cleaned flux solution returned back to the basin. The unique design of the filter press enables the amount of the returned flux, which contains valuable zinc chloride, to be optimised. The fully automated system is controlled by sensors that analyse the incoming flux and the cleaning results. The sensors also enhance safety. For example, if the pH drops below the set level due to a too low ammonia concentration, the alarm will go off and the device stops. The hydrogen peroxide content can be monitored on displays and set to the optimal level in order to accelerate the iron removal.
With the exception of the electric mixing pump, the system operates with compressed air. This eliminates the risks of overheating and short circuiting electric pumps; the electric mixing pump has an alarm for overheating. In addition, there are no metal parts in the pumps, which eliminates the risk of corrosion. All the pumps are clearly marked with numbers to facilitate operations. No maintenance is normally required, but if something does need to be repaired, this can be done with easily changeable spare parts. The control panel is also equipped with a portal for remote monitoring.
The new iron removal device will improve Teknotyö Kuumasinkitys Oy’s entire hot-dip galvanising process by automating flux cleaning, minimising the lost zinc due to the efficient and optimised iron removal process, and maximising quality by decreasing the amount of ashes.
“Ash is a quality issue that not only impacts the final result but also causes extra work phases after the hot-dip galvanising process. It also binds zinc, which is the biggest cost factor in the hot-dip galvanising business,” explains Mika Linnainmaa, owner of Teknotyö Kuumasinkitys Oy.
“We wouldn’t have found this solution without Algol Chemicals and the expertise of their sales manager, Niko Mikkola. Numerous sales representatives contact me about their products, but it’s always a risk to add something new to the chemical process. If the new product doesn’t work, the whole basin content has to be emptied and delivered to a cleaning station. In the worst cases, the entire galvanising process is threatened. With Algol Chemicals, I feel we’re in safe hands and that the solutions and products offered are truly going to improve the processes and profitability of our business,” Mika Linnainmaa adds.
The new device can remove up to 80kg of iron from the flux solution per 24-hour day, and it will improve the flux quality immediately. Totally clean flux will be achieved within a few weeks. This will directly reflect on the quality of the end product, the consumption of heating energy, the amount of iron waste, and zinc costs as a result of decreased ash.
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