Bulk Handling Technologies’ Tyre Driven Ball Mills provides a robust and reliable solution for lime slaking and similar wet grinding applications.
Lime slaking is a common process that involves mixing quicklime or calcium oxide (CaO) with water to produce calcium hydroxide (Ca(OH)2). In most cases, this slaking process is done with an excess of water to produce a slurry called ‘Milk-of-Lime’ (MOL), which has a solids content ranging from 15 per cent to 25 per cent. This is an exothermic reaction which generates heat and steam.
There are several types of lime slakers on the market. The most straightforward systems mix the quicklime in an agitated tank or chamber to produce the MOL slurry. However, they then require a separation system or screening to remove impurities and grit. While this may be practical for small-capacity systems using clean, potable water, it is less common for larger installations that must use raw or process water and where particle size is essential for the process.
Horizontal ball mill slakers are adaptations of standard ball mills designed specifically for lime slaking applications. They have key advantages over other types of slakers.
Horizontal ball mill slakers are suitable for higher slaking capacities. They can be operated even when the available water is high in sulphate or sulphite and do not require a hot water supply to ensure an efficient reaction.
Compared to other slakers on the market, the horizontal ball mill slaker eliminates the need for a grit discharge system. Importantly for process engineers, it provides a high degree of control over the final particle size and can be designed as open or closed-circuit grinding systems, which can suit many different types of operations.
The Tyre Driven Slaking Ball Mill from Bulk Handling Technologies (BHT) is the result of many years of experience in lime slaking systems and ball mill research, development and design. The Perth-based company designed its lime slaking mill range to incorporate a range of features to improve reliability and performance.
Since its establishment in 2012, Bulk Handling Technologies has specialised in customised and innovative solutions through its extensive range of materials handling equipment and systems.
The BHT lime slaking mill range covers a dry feed capacity from 2 to 25 tonnes per hour (TPH), with diameters from 1 metre up to 2.5 metres.
Paul Ingleson, manager at Bulk Handling Technologies, told ABHR that the key to the ball mill slaker’s versatility is the pulverising action produced by the steel balls against the quicklime.
“The combination of impact and grinding ensures excellent particle fineness and also creates a highly reactive slurry—even when faced with lower-quality quicklime or challenging slaking water,” he said.
“Any grit in the quicklime feed is also pulverised alongside the quicklime and is incorporated and suspended in the slurry.”
While the MOL slurry produced by slaking is often not the end product itself (instead, it is an additive into the main process), the slaking system must be robust and reliable so that it can run with minimal operator involvement. The ball mill is the system’s key component and must be correctly matched with a suitable mixing feed bowl, feed pipe and discharge hopper with a scats-trommel screen.
In addition to the reliability and simplicity of the tyre-driven design, features such as integral hydraulic shell supports and feed pipe extraction rails ensure that BHT Tyre Driven Slaking Mills are also easy to maintain.
“Our high-efficiency Vortex Feed Bowl ensures proper pre-wetting and introduction of quicklime and water into the mill without blockage, while the BHT impingement scrubber draws steam through the mill away from the dry feed,” Ingleson said.
Ingleson said the Perth-based company had vast experience in providing customers with a solution for this exact type of application.
“We can offer a complete lime slaking system suitable for remote installations in Australia or anywhere in the world,” he said.
“When the Tyre Driven Slaking Ball Mill is combined with BHT’s ultra-low vibration bin activators, large-capacity bolted bulk storage silos and ancillary feeding and classification equipment, businesses have a complete solution.
“We can also assist with site audits and troubleshooting and, where practical, provide refurbishment and upgrade options.”