Diamonds

Introduction

With numerous successful Weba Chute System installations in the diamond-mining industry, we have proved that our scientific approach to the dynamics of bulk materials handling can eliminate the problems associated with conventional transfer chutes. This practice provides significant cost savings in the diamond-mining industry.

In addition to long-term refurbishment contracts at some major diamond mines, Weba Chute Systems has also introduced specific innovations for the diamond-mining industry. These include a slurry screen splitter distributor system that allows for a nominal belt capacity of 600 tph, with a water and effluent addition of 1 080 m3/h at a particular diamond mine.

Bulk materials handling poses a significant challenge in the diamond-mining industry, where conveyor systems have to deal with belt speeds from 2.5 m/second to 5 m/second. Our significant intellectual capital of “the perfect transfer point” includes conveyor-to-conveyor, conveyor-to-stockpile and conveyor-to-screen applications.

We consider a holistic, custom-design solution that focuses on the entry and exit points and incorporates control of material flow, volume and velocity during the transfer process. The result is a transfer point that substantially reduces maintenance expenditure in the diamond-mining industry.

Overview

Our transfer point solutions operate between a crusher and material stockpiles, addressing challenges such as the high impact on the belt, excessive dust and spillage (resulting in increased maintenance costs) and plant stoppages caused by the ineffective transfer point.

By controlling material flow, we can reduce the impact of the product when it reaches the conveyor, which decreases wear on the belt and reduces spillage and dust. We also address managing large particle sizes (which cause frequent replacement of transfer chutes) to mitigate challenging conditions and regain uptime and productivity for our clients.

One such intervention was staged at Boteti mine in Botswana. The run-of-mine material at the operation had lump sizes of up to 1,200mm fed to a grizzly feeder from an apron feeder, with oversize material going to a jaw crusher. However, a primary issue was the lump kimberlite, which along with the uncontrolled material, resulted in stress to the transfer system.

Another challenge in this primary circuit is the conveyor, which receives material from the grizzly underpan and jaw crusher discharge. Lack of material control caused a high impact on the conveyor belt, damaging the conveyor and causing considerable spillage. All these factors resulted in unplanned downtime due to frequent conveyor belt replacements.

We engineered an integral swing mechanism to guide large lump sizes through the transfer point at a controlled velocity, reducing the impact on downstream equipment. Therefore, the next chute in the process flow no longer has to deal with the disproportionate impact. The material then flows through the grizzly discharge chute and reports to the crusher. The longevity of the chute vastly improved and, since its installation in 2017, has not needed to be replaced.

The mine’s grizzly underpan chute system (for lump sizes of -250mm) was designed to accommodate the material. However, a drop height of about seven metres from the grizzly feeder to the conveyor (along with the lump size) could result in a challenging transfer point. The chute design used in this instance accommodates the material flow so that it is controlled, and the receiving conveyor no longer endures excessive damage.