The benefit: Large chunks of rock no longer block the crusher making the mining process safer and smoother. The results: Far fewer production interruptions, less losses and, all in all, a far more efficient iron ore crushing process.

“This is a pioneering project. This project was a landmark for Carajás (The biggest iron ore mine in the world) due to its innovation,” said José Cléber Rodrígues da Silva, Engineering Maintenance supervisor at Carajás. “There was nothing like it before. The screener was created and developed to address the negative impacts of large blocks of iron ore on crushing plants.”

The screener is formed by several 3m x 3.30m fixed grids with a shape specially designed to withstand the impact of the large rocks and optmize the iron ore flow. They are mounted on a 2m-high 21m x 18m supporting structure, which in turn is placed on top of the ore hopper. Its loading capacity, is powerful and huge: up to 1,200 metric tons of iron ore distributed and can support impact loads of 120 metric tons .

“The main reason for using Hardox was the combination of high hardness, excellent mechanical properties and toughness.” José Cléber explained that due to the high level of loading in the application, Hardox 450, with the yield strength of 1200 Mpa, worked very well. “In addition, the hardness of 450 HBW ensured the wear resistance to the flow of iron ore on the screen”.

Mr. José Cléber said the practical tests yielded even better results than the screener modelling suggested: The reduction of downtime due to (iron ore) block obstruction was 92% and the reduction of costs of losses arising from stoppage amounted to little more than three times the value of the project. This means, the project was paid in just one month.

Indeed the solution addressed a recurring and expensive problem in mining: the high incidence of large blocks beyond the capability of feeders that can damage the ore crusher. These blocks measuring between 2.5m and 3m and weighing between 21 and 50 metric tons can cause crushing plant obstruction and stoppage for hours or even days.

The screener’s estimated lifespan is 2 years in 24/7 operation, which is a long time in mining terms, an industry in which tear and wear are a constant challenge to continuous production. Even a brief halt in mining production can gravely impact economics as it’s very costly to restart production.

As one of the largest mining companies in the world, Vale seeks sustainable development and operational excellence in all its activities. Innovation and improvement are key to their operations.

The Swedish Steel Prize jury’s motivation:

Utilizing Hardox 450, that combines strength and toughness with wear resistance, Vale has designed a new generation of screening grids for application primarily within large-scale mining and quarries. The grid geometry and the cutting of single plates are unique compared to that of traditional square patterned networks. The new grid gives less downtime due to better flow of material and easier maintenance which give large economic as well as environmental savings