Weld reclamation repairs to gearbox casings and rolls

Cleveland Potash, a business unit of ICL Fertilizers, is a producer and supplier of potash fertilisers for agricultural and industrial applications based in Saltburn-by-the-Sea, on the North East coast of England. The company operates the UK's only potash mine, from which it produces approximately one million tonnes of potash for fertilisers and around half a million tonnes of salt each year.

Potash is used for a variety of applications, including fertiliser production, glass making, sugar beet cultivation and in the chemicals and pharmaceuticals industries. The salt from Cleveland Potash is used primarily for road de-icing.

The potash and salt deposits are mined from beneath the North Yorkshire Moors and under the North Sea. The mine here is almost one mile deep (the deepest in Europe), stretches for six miles inland and seven miles under the North Sea. The working environment for equipment and machinery is extremely harsh.

Gearbox casings and crusher rolls

CNES has been working closely with Cleveland Potash since 2001. Andy Bland, Business Development Engineer at CNES comments: "CNES does a variety of work for Cleveland Potash, including weld reclamation on crusher rolls and refurbishment of large gearbox casings. Cleveland Potash came to CNES because of a combination of the company's engineering expertise, recovery and workshop facilities. We also have a history of working with large industrial gearboxes. Most of the refurbishment work we do involves no detailed drawings of the gearbox, just a general arrangement drawing, which means you need to rely on the skills and experience of the engineer – which we have here."

At the Cleveland Potash mine, the six-tonne gearboxes drive cutting machines that cut away more than one million tonnes of rock each campaign from the face of the mine. Bland explains: "Because of the harsh, corrosive working environment in the mines, the auger gearboxes last for around two years before they need a complete overhaul. CNES carries out between three and four overhauls each year for Cleveland Potash."

The gear casings are sent to CNES' Teesside workshops as empty shells, stripped of their component parts. CNES then shot blasts the casings and all working surfaces, checks the alignment and condition of the bearing housings, then submits a full inspection report to Cleveland Potash. This includes specifications of how CNES intends to reclaim the casings to the original dimensions.

Bland continues: "We also carry out weld reclamation work on crusher rolls, which have a value of around 150,000 euros per pair. These crusher rolls are used to fine-grind the salt and potash. Cleveland came to us because we developed a weld reclamation process that saved the company around 60 per cent of the cost of purchasing a brand new pair of rolls."

Weld reclamation and metallurgical experts at Corus developed a specific welding procedure for the Cleveland Potash crusher rolls. The weld reclamation machine at Scunthorpe operates continuously on the rollers for 365 hours, depositing a special 120mm thick hardened layer onto the rollers. The rollers undergo an intermediate stress relieving operation halfway through the welding process. CNES' welding experience and engineering skills enabled it to develop this custom process for the client.