Quarrying

Reliable level measurement with radar sensors

How VEGA’s radar level instruments helped improve a Fujairah quarry’s efficiency and throughput.

Automated level measurement in a stone crusher

Measuring the level of material in a crusher has different purposes. For instance, it helps maintain a sufficient level of material to optimise the rockonrock compression into the crusher, maximising throughput. It is also mandatory to monitor and control the level to avoid the crusher from choking or overfilling, both resulting in unplanned shutdowns and tedious maintenance operations. “Our production rate is 650 MT/hour and about 12,000 MT in a day, so optimising the crushers is key to productivity and any downtime is not an option for us. Additionally, if any crusher is overfilled, this presents a potential hazard for any workers in the area. This is why on our site we automated our crusher lines and favoured VEGA’s reliable measurement technologies,” explained Ishteyaque Ahmad, plant manager, Power International LLC.

Costeffective

All mining companies and quarries aim to run their productions smoothly, without downtime, minimal material loss and to maximise their revenues. Some companies, however, still hesitate to take the leap to invest in automated instruments, historical reasons being the high costs involved in a fully automated system and field sensors, which were also laborious to install and commission. Stateof the art devices such as radar level sensors (for example, VEGAPULS 69 radar), have become more affordable over the years, due to technological advancements as well as R&D. Equipping even the smallest sites is now a possibility with VEGA’s spectrum of sensors. “Instrumentation is an indispensable part of our site and allows us to have a smooth operation and to optimise the flow of material significantly. Investing into modern technologies, such as 80GHz radar level sensors, is a strategic step towards excellence and efficiency,” remarked Ahmad.

Automated crushers with noncontact radar

Adjusting the speed and controlling the conveyor belt is the way to manage the flow of material into the crusher. To do so, accurate level measurement is required, and this is critical information for a plant operator.

There are many ways to measure the level, and ensuring the right technology is an important step for an autonomous crushing and screening line.

The environment, such as, dust, noise, vibration, heat, buildup, rock projections and othersare what makes this measurement complex.

Mechanical systems such as tiltswitches are at the frontline of this demanding application. Tiltswitches have been used in this industry for decades. Unfortunately, as they need to be in contact with the material, they are subject to wearing and intrusive maintenance or replacement. Additionally, such devices can only act as a high alarm and do not provide live feedback on the material height or percentage of material into the crusher. Thus, the use of such technology comes with limitations.

It is not rocket science that noncontact sensors might be a better choice for rock level measurement. And there are plenty of alternatives such as lasers, cameras and ultrasonic sensors.

However, they are almost always affected by the heavy dust, vibrations or moisture buildup, conditions synonymous with a quarry or mining site.

But one technology rises above the others: the 80 GHz Radar. Unaffected by site conditions, noncontact radar sensors perform well with all bulk solids.

The VEGAPULS 69 from the German manufacturer VEGA, in particular, delivers extremely reliable and accurate measured values. The radar sensor operates at a high frequency (80GHz) and embark an advanced electronic which negates the influence of buildup.

Moreover, the microwave based technology does not rely on the surrounding conditions to proceed with the measurement. The physical properties of microwaves allow them to pass through thick layers of dust or humidity and remain unaffected by heavy sun exposure.

Further, by providing live data, the radar level sensors act as an overfill protection, allowing operators to control the conveyor belt speed to avoid unnecessary wear of the machines and avoid stoppages. ■

Automated stone crusher equipped with a VEGAPULS 69 radar sensor.