Chromite Sand
Specialists in Chromite Sand
Chromite is a naturally occurring mineral in the form of an Iron Chrome Oxide FeCr2O4 where the Fe can be substituted by Mg form MgCr2O4 and some cases Al2O3. South African Chromite have all the above elements Mg Al and Fe Chromite MgFe(Al Cr)2O3.
Chromite ore concentrate is the raw material used for sands processing (beneficiation) of different grades: Foundry, Chemical and Refractory grade. All chemical and physical properties don’t change with the beneficiation process.
Chromite Sand
Chromite sand Foundry grade has been the preferred raw material for the elaboration of resin bonded casting cores and moulds in the steel foundries for many years.
Occurrence
Chromite is found in basically three forms or deposits classified as Stratiform, Pediform and Beach Sand. South African and Zimbabwe have got the largest Stratiform deposits in the world which are large masses of igneous rock that have cooled very slowly in subsurface magma chambers. During this slow cooling, chromite and associated minerals have crystallized early while the magma is still at a very high temperature. Their crystals then settled to the bottom of the magma chamber to form a layered deposit. Some of the layers in these deposits can contain > 50% Cr2O3 based on weight.
Advantages
- High affinity – high melting point 2150°C
- Very low thermal expansion with excellent dimensional stability
- High density material
- High thermal conductivity
- Excellent thermal shock resistance
- Control on the AFS for high permeability
- Compatibility with molten metals/slag
- Can be recyclable and reusable
Beneficiation
Refcor LTD South African’ partner uses an initial washing process to reduce the Silica content (values below 0.8%) while also controlling the pH and turbidity (impurities). A second step take place where a drying process follows in order to reduce the humidity to <0.2% The final drier product is the bagging double layer big-bags (1 Ton suitable for export).
Versatility of an additional screening process is offered when requiring less than 1,2 fines < mesh#100 or any other specific grain size distribution required.
The residuals obtained from discharging the fine and coarse grains are then transferred to other production process milling, an specific size distribution of fine grains is also require to obtain chemical grade for pigmentation of glass bottles.
Quality and certificates
The Ore concentrate received in our beneficiation plant is tested before the washing process takes place. An output sample of wet chrome sand is taken for chemical testing to measure the SiO2, turbidity (impurities) and pH. The material is then taken to the Drying plant and depending on the customer demand – if required – it is once again passed for a screening after drying in order to reduce the fines to required level. A first AFS test and calculation is obtained in our own laboratory but, another samples are outsourced i.e. Bureau Veritas to get a third party quality certfication for client approval.
