Valoxy---SampleDescription

Valoxy is an alumina-rich substance that may be used in certain applications as an alternative to alumina and bauxite. Typical values of the main constituents are shown below (dry basis):

Al2O3
70%
MgO
8%
SiO2
4%
CaO
2%
Chloride
<0.5%
Moisture
25%
Typical mineralogical composition is as follows:
Spinelle MgAl2O4
30-35%
Corundum Al2O3
8-12%
Aluminium hydroxide Al(OH)3 ­
25-40%
Amorphous
20-30%

Applications

Cement Clinker

Valoxy has proven to be a valuable additive in cement manufacture. Valoxy may be used to introduce alumina into the clinker burning process of the cement kiln. High alumina content is important for the formation of calcium aluminate complexes in the cement. Moreover, Valoxy’s fluorspar content enables the formation of a calcium fluoride/calcium aluminate-based mineral important to cement production.

Refractories and Ceramics

Materials resistant to high temperature are made from materials such as alumina, bauxite, corundum, spinelle and aluminate cement. Valoxy may act as a source of alumina in ceramic and refractory applications. In addition, independent studies have demonstrated that Valoxy may replace fireclays in the production of clay products such as building blocks, pavers, flu lining materials and insulating firebricks.

Chamottes

The most common source of material for fireclay refractories are fireclays – naturally abundant sedimentary rocks. The performance of low-grade refractories may be enhanced by the addition of alumina-based chamottes. Compared to traditional chamottes such as quartz sand, Valoxy demonstrates performance and cost advantages. Within certain service temperatures, Valoxy maintains a thermally stable and open structure on firing and avoids the problem of micro-cracking associated with quartz inversion on cooling.

Mineral Wool

Alumina is added in the manufacture of mineral wool to reduce solubility of dust particles in lung fluids preventing bronchial problems for operatives. Valoxy may have a role as the alumina source.

Stainless Steel Slag Conditioning

In trials Valoxy improved the properties of AOD slag from stainless steel production, compared to traditional treatments such as boron. Treatment with Valoxy resulted in a slag with similar micro-hardness, improved chromium entrapment and better microstructure (lower porosity) compared to boron. This offers stainless steel producers the potential for significant economic benefits due to:

(a) Valoxy’s low cost compared to boron

(b) A higher value for the slag as construction aggregate.

Geopolymers

Valoxy may have a role as the aluminosilicate source in the basic geopolymerization reaction. Combined with a highly alkaline solution, Valoxy may be a precursor for geopolymeric materials offering improved heat resistance produced at a much lower temperature than traditional fired products.

In lab trials a Valoxy-based geopolymer exceeded the demands of the most rigorous fire standards for tunnel protection currently available (RWS:  1350°C for two hours).

Calcium Aluminates

Calcium aluminates are used in two main applications:

  • Quick-setting cements
  • Synthetic steel refining slags to remove sulphur, phosphorus and aluminium oxide from molten steel.
Calcium aluminates are produced by combining bauxite with lime. Valoxy may have a role as the alumina source instead of bauxite.

Benefits of using Valoxy
For the above applications, even partial substitution of bauxite/alumina by Valoxy could substantially reduce formulation raw material costs. The benefits of using Valoxy are process-specific. Valoxy must therefore be technically validated in the application for which it is intended.
  •  Stability: Valoxy offers reliable supply at a consistent price. By contrast alumina and bauxite are subject to significant fluctuations in availability and price.
  • Cost savings: Valoxy may lower sintering and burning temperature and thereby reduce energy costs. Fluxing properties may reduce fuel consumption. Valoxy demonstrates cost benefits compared to traditional chamottes. Weight-for-weight, the alumina content of Valoxy is very inexpensive compared to conventional aluminas.
  • Performance: Valoxy may reduce the setting time of cement and purification time with synthetic steel slags. Valoxy avoids micro-cracking on cooling in ceramics fired in the temperature range at 1,100-1,200C.

To download  Valoxy data sheet click here.

To download a review article on Valoxy click here.