Microsilica: a raw material of choice for shaped products in refractories
Refractories: meeting every challenge with a wide range of materials and formats
Refractory materials are used to provide linings in a great variety of high-temperature processing units: from 600 °C degrees in cooking ovens to over 1700 °C in hot metal treatment, via 1100 °C in petrochemical processing, 1450 °C in cement clinker sintering, etc.
Refractory materials are designed and delivered with diverse mineral and chemical characteristics and in different formats: castables, prefabricated pieces and shaped products. The latter, which this article examines, are refractory materials delivered as pieces of different sizes and shapes. These ‘building blocks’ are prefired and installed using standard masonry techniques. This differs from castables, which are batches of refractory powders prepared for direct use in their state of delivery (often transformed into monolithic or seamless refractory linings), mixed with liquids and, if required, one or several additives. Shaped products also differ from prefabricated pieces, which are moulded or precast components, often with complex forms, used for direct installation in functional parts of furnaces and kilns.
ELKEM MICROSILICA®: the quality benchmark for high-performance shaped products
The advantage of shaped products or refractory bricks is that they can be customized in terms of size and material content to adapt to temperature profiles and thermal variations, to protect against corrosion and slag, to repel melted materials in contact with the refractory lining, and to be fitted to the geometrical parameters of the shell. Shaped products also allow for a wide choice in installation processes, taking into account economic factors such as cost of materials, equipment required, labour costs, work legislation and contractual or regulatory requirements, as well as time constraints and the availability of installation skills and local service providers.
The performance of shaped products can be customized with microsilica to meet specific processing and end-product features and offer refractory manufacturers the added advantage of being pre-tested off-site to ensure they meet customer applications before installation. This allows manufacturers to choose exactly the forms they need in terms of size, format, physical performance and chemical resistance in the refractory shell, to ensure the integrity of critical parts at high temperatures and variable heating/cooling cycles, resisting chemical corrosion and mechanical stress. Shaped parts manufacturers can also use additives to improve flow of dry powder, improve densification and obtain millite/forsterite formation at high temperatures.
Elkem, the global leader in microsilica technology, provides a wide choice of ELKEM MICROSILICA® products for shaped parts. These customized co-products of silicon or ferrosilicon manufacturing are composed of ultrafine, amorphous spheres of silicon dioxide (SiO2) and feature high-purity properties, which can have a strong impact on the specific performance requirements of various high temperature applications.
Here is a non-exhaustive list of our product offering for the making of shaped products, many of which are also appropriate for castables (unshaped products) and prefabricated pieces. Elkem experts, technicians and sales staff are available to explore the right solutions for your specific applications:
Silicon based materials for refractories
Elkem Microsilica® 971
The ELKEM MICROSILICA® 971 product, a high quality, purpose-made, low-impurity grade, for versatile applications in refractories, available in densified (D) or undensified (U) form, to be used in advanced refractory products such as self-flowing, low, ultra-low and no-cement castables.
Product data sheet
Elkem Microsilica® HQ
The Elkem Microsilica® HQ product is a cost-effective alternative for low cement castables, with controlled and stable chemical composition, based on low alkalis and higher reactivity.
Elkem Microsilica® 968
The ELKEM MICROSILICA® 968 product, a cost-effective alternative for low cement castables, featuring a controlled and stable chemical composition.
Product data sheet
Elkem Microsilica® 955
The Elkem Microsilica® 955 product, a medium-quality grade silica fume with tight specification limits based on in-process control, resulting in higher silica content and reduced impurities.
Product data sheet
Designed for microsilica-containing LCC and ULCC, based on Al2O3 - SiO2 system with quick wet-out and low water demand.
Designed to act as an accelerator in undispersed aluminosilicate systems like dry gunning LCC and ULCC mixes without clay.
Designed for microsilica-gel bonded systems (NCC) to control the working and demoulding time and to develop high green-strength at room temperature.
Designed to work as a multi-functional microsilica dispersant, for aluminosilicate LCC, ULCC and NCC, giving customers freedom to fine-tune their products with other additives (accelerators, retarders, etc.). It enhances the rheological properties, reduces the water demand and increases the flow. Suitable also for shotcreting.
By combining both SioxX®-Flow and SioxX®-Set products, setting can be controlled. SioxX®-Flow product will also work in combination with Silica-Sol (colloidal silica) in NCC to control flow, working and setting time.When used in silica-sol systems a separate gelling agent needs to be added.
Designed for undispersed systems mainly for NC gunning mixes. Can also be used for LC and ULC gunning. In castables and shotcrete (dispersed systems) SioxX®-Set can be used as accelerating agent.
SioxX®-Ten / SioxX®-Ten PLUS
SioxX®- Ten and SioxX®- Ten PLUS are primarily designed for ultra low cement alumina-based or microsilica-gel bonded no-cement castables.
SioxX®- Ten mainly works at the range of 800-1100ºC, while SioxX®- Ten PLUS is recommended to work at the range of 600-900ºC.
Both of them enhance the rheological properties, reduce the water demand, increase the flow, control the working and de-moulding time, help develop high green strength as well as high strength at the indicated working range of temperature.
Designed for basic (MgO-based) refractory castables, to help avoid inherent problems of crack formation and poor workability. For advice how to best use our Specialties, contact our competent technical staff.
Our Product Data Sheet center
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Discover the different silicon based materials for refractory applications, each with unique properties that are specifically crafted to meet the demands of high-temperature environments.
Silica Fume / Microsilica
Silica fume is a byproduct of the production of silicon metal or ferrosilicon alloys, and is a highly reactive pozzolanic material that is used as a supplementary cementitious material in concrete to improve its properties.
Silicon powder / micronized silicon
Silicon powder is a finely ground, micronized form of elemental silicon that is used in a wide range of industrial applications, including metallurgy, ceramics, electronics, and more.
Specialties for Refractories
Specialties for refractories are various types of silicon products specifically designed for use in high-temperature applications.
Elkem Materials Mixture Analyser
Get the best out of Elkem's Silica fume / Microsilica material by leveraging upon our world reknown software to optimize your mixture.