Microsilica: a key raw material for prefabricated parts in refractories
Refractories: meeting complex requirements using different 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 based on diverse mineral and chemical characteristics and in different formats: castables, shaped products and prefabricated parts. The latter, which is the subject of this article, describe refractory materials delivered in prefabricated parts or precast components for direct installation in functional parts of furnaces and kilns. One of the main advantages in using prefabricated parts is significant reduction in installation time and therefore lower downtime in existing systems, as well as streamlining maintenance and repair of damaged parts.
Microsilica: enabling the manufacturing of versatile and sophisticated precast parts
Modular prefabricated parts provide specific thermal and mechanical features, which can be pre-tested off-site to ensure they meet customer applications before installation. This allows manufacturers to make very sophisticated forms for refractory linings outside of the burner unit, allowing kilns and furnaces to keep functioning. This also enables refractory parts manufacturers to line existing critical parts with higher-grade materials, improving physical performance and chemical resistance in the refractory shell, including:
- Protecting the integrity of critical parts from elevated temperatures, while maintaining continuous high temperature and reducing heat loss and resisting chemical attacks, as well as mechanical stress due to extreme heat or periodical heating/cooling cycles in all parts
- Preventing unwanted reactions, such as abrasion or chemical reactions, between the shell, the raw material and the end-product in all parts of the refractory
Elkem, the global leader in microsilica technology, provides several advantages for precast parts, because it enables the fabrication of more flexible parts that are easier to install and fit perfectly into existing structures. ELKEM MICROSILICA® products for prefabricated parts are customized co-products of silicon or ferrosilicon manufacturing, composed of ultrafine, amorphous spheres of silicon dioxide (SiO2). They feature high-purity properties, which can have a strong impact on the specific characteristics needed in various applications, at high temperatures.
Typical parts made with prefabricated shapes include calciners, inlet chambers, nose rings, ear roofs, kiln hoods and slot coverings, dams and weirs in reheating furnaces, pouring tips, taphole blocks, cooler inlet throats and benches, bullnoses, insulation for roller hearth furnaces, etc.
They are also used for burner blocks and inner and bottom ceramic air and gas nozzles, as well as ladle lining (for the aluminium industry).
Here is a non-exhaustive list of our product offering for the making of prefabricated parts, many of which are also appropriate for shaped and unshaped products. 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.