|
The Group's core technology is the RockTron Fly Ash Beneficiation Process. This proprietary process converts waste from coal-fired power stations (fly ash) and separates the constituent minerals to produce a range of sustainable, environmentally-friendly products with unique physical and chemical characteristics.
At the heart of the RockTron Process is a standard mineral processing technique called froth flotation. First patented in 1905, this technology involves certain minerals attaching themselves to air bubbles and rising from the residue. It has been widely used in the mining industry for many years. RockTron has refined and enhanced this long-established methodology to create a new, proprietary process.
We have successfully developed a means of utilising pneumatic flotation cells, which are specially designed for fine particle separation, to produce a high-grade coke (coal without volatiles) concentrate together with a high specification pozzolan.
The RockTron process uses water. There are no problems with dust control and the individual unit processes (e.g. carbon recovery, particle classification etc.) are inherently more efficient than dry processes.
A major advantage of RockTron froth flotation over other carbon separation techniques is that it produces a high-grade coke product at high component recovery. Typically, our process produces coke products with a 92%-96% purity. The table below provides a guide to the performance of RockTron’s froth flotation compared to another carbon removal system, based on an assumed feed of 12% carbon.
The limiting constraint for the use of traditional fly ash as an Ordinary Portland Cement (OPC) substitute has been the carbon content (LOI). Under the BS EN 450-1:2005+A1:2007 specification the LOI content needs to be below 7% of the total fly ash. The RockTron process produces a superior low coke product.
| |
Stream 1 - Coke Product
|
Stream 2 - Clean Pozzolan
|
| |
Purity
Purity
Grade
(%)
Purity
|
Efficiency
Efficiency
Component
=Recovery
=(%)
of total
content
|
Yield
Yield
Mass
Recovery
(%)
|
Purity
LOI
(%)
|
Efficiency
Component
Recovery
(%)
|
Yield
Mass
Recovery
(%)
|
| RockTron |
94
|
90
|
11
|
<2
|
99
|
89
|
| Other |
38
|
67
|
21
|
<5
|
85
|
79
|
Grade is the mass percentage of the component (e.g. carbon) in the stream. This is used as a measure of 'purity' of the product stream. Component recovery is the percentage of the total component originally present in the feed that reports to the stream. This is used as a measure of 'efficiency' of the separation process. Yield is a measure of the percentage by mass reporting to a given product stream.
Mass recovery is the percentage of the total feed reporting to the stream. This is sometimes called yield in simple systems, but is not the same as component recovery, and simply indicates the mass split between the products.
We use a number of additional innovative mineral processing techniques to complement froth flotation to achieve the high level of carbon separation, purity and produce a range of minerals, including:
- Cenosphere (CenTronTM range of products) recovery and cleaning
- High-grade coke recovery
- Magnetite (MagTronTM range of products) recovery
- Classification of cementitious products (RockTron Alpha and Delta)
- Mineral fillers for polymers and coatings (MinTronTM range of products)
|
|
A 70t/hr commercial coal from ash plant was built at Lünen in Germany in 1989 (commissioned 1990) and operated profitably for 7 years until the feedstock was exhausted.
Lünen Plant, Germany
Advantages of the RockTron Process
RockTron’s unique process:
- Treats both fresh fly ash and that stored in either stockpiles or lagoons.
- Is operated at a constant rate all year, irrespective of seasonality.
- Uses new and well-established mining and mineral processing technologies in an innovative and proprietary combination to deliver sustainable and consistent product quality.
- Facilitates eventual full land remediation of stockpile and lagoons.
- Produces large volumes of low LOI cementitious products having consistent quality and colour.
- Produces high-grade coke products.
- Gives significant economic benefits including operational savings and fly ash management costs.
- Increased efficiency attributable to re-firing of the recovered coke in the power station and reduction in land fill tax. Ultimately there are also savings in reclamation costs for the ash dumps or lagoons.
- Gives substantial environmental benefits: e.g. cement constituents from each plant could potentially reduce ordinary Portland cement (OPC) production by an equal amount, thereby reducing CO2 emissions by approximately 0.9 tonne per tonne of cement replaced.
- Offers the possibility of Carbon Credits to cement producers.
- Significantly, 100% of the feed is recovered as product.
|
Home
