Client
Uranium ore processing plant
Challenge
A uranium processing plant was experiencing premature failure of OEM Bisalloy 400 liners in the mill feed chute causing production delays.
Castech Solution was tasked to increase the life of the liners in the rock box without having to modify the supporting structure.
Solution
After an initial site evaluation, we identified the liners were operating under extreme erosive and corrosive conditions.
To improve the performance of the Chute, we approached two aspects of the problem – the physical design of the liners and material selection.
Liner Design
- Prevent ‘racing’ between mating liners – by taking advantage of the freedom of shape that casting allows, our engineers designed a saw tooth solution staggering the mating joints to minimise the “racing”erosion of the original continuous joint line design.
- Variable thickness to balance wear – the sectional thickness was increased in the high wear zones to balance the wear rate across the entire liner and extend service life.
- Reduce change out time and improve safety – redesigning the liners offered an opportunity to reduce the change out time, by introducing a reverse taper edge design, allowing worn liners to be easily replaced without having to remove the adjacent liners.
Material Selection
- Minimising erosive and corrosive wear – analysis of operating conditions highlighted corrosion as a major contributor of wear due to the pH 3.4 process water. High Chrome White Iron was specified because its properties provide a combination of abrasive wear resistance with a bulk hardness in excess of 600HB plus Cr carbides in the matrix (compared to Q&T Plate @400HB) and corrosion resistance in process water of pH 3.0 to 9.5 (compared to quench and tempered plate at pH 5 – 8).
Key outcomes & benefits
The project demonstrated that:
- The solution extended the wear life from 5 weeks to more than 16 weeks
- Change out times reduced by two thirds
- Castings’ freedom of shape allowed us to optimise the chute liner design
- Combined understanding of operating conditions and material properties resulted in wear life extension