Custom seal protects against water ingress in mining machinery

Eriks has recently demonstrated its ability to provide bespoke seals for equipment used in the most extreme environmental conditions, with the development of a new carbon-faced Rotary Joint that transmits minewater under high pressure into the heads of seamless continuous miners manufactured by USA company, Bucyrus. Following extensive testing, the Rotary Joint, designed and produced by Pioneer Weston, a division of Eriks Sealing Technology, is now fitted as standard on the Bucyrus continuous miners; the first machine fitted with the seal is being used in Pittsburgh, USA, for coal extraction.

Bucyrus is a global market leader in Longwall mining systems due its ability to offer optimally harmonised system components from a single source. The resulting systems guarantee high reliability and safety while minimising production costs. In addition, although operating in one of the world's most demanding production environments as deep as one mile underground, the Longwall systems ensure high productivity, outputting up to 5000 tons of coal per hour.

A key component in Bucyrus' Longwall systems is the company's range of continuous miners; it is these machines that drill into the coal face and extract material at a phenomenally high rate for transportation to the surface via fast Longwall conveyors.

Dust control

Until quite recently the continuous miners operated without any external equipment to mitigate the effects of dust. However, new regulations have been introduced in the USA that require dust levels to be significantly reduced, so water jets are directed at the heads of the shearer while they are in operation.

The problem with this system is that water can enter the drill head and cause corrosion, leading to premature failure and lost production. Faced with this problem, Bucyrus turned to Pioneer Weston to engineer a solution. With over 50 years' experience in design and manufacturing experience of customised sealing systems, as well as a standard range of mechanical seals, both the division's custom-designed and standard, metal-faced seals are used in applications as diverse as nuclear submarines, paper mills, steel mills, power stations, earth movers and bakeries.

Development of the custom seals for Bucyrus began with a visit to the USA from an engineer from Pioneer Weston to view the application and discuss a possible specification. Following this visit, a prototype seal was designed and manufactured and shipped to Bucyrus for evaluation at a mine in Pittsburgh. Pennsylvania.

Rotary joint design

This Rotary Joint, a 23-inch diameter unit with specialist carbon faces, is enclosed in a large housing, which is electroless nickel plated to protect against corrosion. The Joint contains water in the drill head, while O-rings provide static sealing for the seal enclosure.

Following successful trials with the prototype seal, and a further visit from a Pioneer Weston sealing specialist, a final specification for the seal was agreed upon, which required only minor adjustments from the original configuration. In addition, Pioneer Weston advised on fitting of the seal to ensure maximum performance.

Extensive testing and development work by Pioneer Weston resulted in a Rotary Joint design that has now been accepted by Bucyrus as standard fitment on its continuous miners; to date, ten of the seal units have been supplied. Chris Dixon, Divisional Sales Director for Eriks Sealing Technology, states: "This prestigious and demanding project with the leading global manufacturer and supplier of Longwall mining systems shows what Eriks is all about.

"It shows that we can deliver sealing solutions where our competitors cannot, and also demonstrates our ability to work closely with customers to achieve solutions that ultimately improve their processes and operations."