Hewitt Robins replaces 50 year old underground screen at Winsford salt mine with state of the art design

Posted by Paul Moore on 29th September 2021

Hewitt Robins was previously awarded the contract to supply the UK’s largest and oldest working mine with a replacement Vibrating Screen. Winsford Rock Salt mine, part of Compass Minerals, previously had a 50 year old GEC 2.5 m x 7 m double deck linear motion screen which was becoming tired, problematic and in need of replacement.

Hewitt Robins was tasked with two main objectives. The replacement screen had to be designed to fit onto the existing structure with no modifications and it needed to be of a modernised design allowing the customer to maintain the machine safely for many years to come.

The main issue with the 1960 GEC Screen was the vibrator unit, which was an old design, wasn’t ideal for maintenance. The vibrato unit had incorporated four heavy eccentric shafts over 3.2 m in length, four timing gears, eight bearings and required over 300 litres of oil.

Hewitt Robins supplied their latest twin shafted, linear motion, eight bearing, self-synchronised pod–style unit. This unit came complete with four vibrator pods, prop shafts between pods and counterweights.

This new design was far easier for the customer to maintain as each pod was only 500 kg in weight and there were no expensive drive or driven gears. Each pod also only requires 2.5 litres of oil, so the machine only requires 10 litres in total. The gearless unit also allowed the pods to run independently  and would self-synchronise to transport the material down the screen deck.
Due to the underground mine restrictions Hewitt Robins designed the machine so it could be disassembled after factory test and re-assembled once lifted down to the mine. The machine had to be designed with a modular support frame so that the major components would fit into the mine’s elevators. Once the components were lifted down into the mine the screen was then re-assembled on site and lifted into position allowing the customer to replace different mats depending on their customer’s needs.
The current screen is handling over 300 t/h of -100 mm rock salt and the screen gives both a 6 mm and 10 mm product depending on client’s demand. This Hewitt Robins screen, that has been in operation for over two years now, is still going strong and will be underground long into the future.