Revealing the secret of magnesium oxide？

Magnesium oxide (MgO): properties, classification, core applications and industrial selection guide Magnesium oxide (chemical formula MgO) is an inorganic compound composed of magnesium and oxygen. It is commonly known as "bitter soil" or "magnesium oxide". It is a basic material widely used in the industrial field. Its core characteristics are high melting point (2852°C), good insulation, corrosion resistance, thermal conductivity and chemical stability. It can be divided into multiple categories according to production process, purity and form, adapting to the needs of multiple scenarios ranging from industrial kilns and ceramics to environmental protection and medicine. The following is a comprehensive analysis from a professional perspective:

1. Classification of magnesium oxide (divided by core industrial uses) 1. Classification by production process (determines purity and application scenarios) Lightly burned magnesium oxide (active magnesium oxide) Process: produced by calcining magnesite (MgCO₃) or magnesium hydroxide (Mg (OH)₂) at 700-1000℃ Features: medium purity (85%-95%), high activity (large specific surface area), easy to absorb water Typical applications: Magnesite cement, rubber filler, water treatment adsorbent, feed additives Dead-burned magnesium oxide (dead-burned magnesium oxide) Process: Light-burned magnesia is produced by calcining (sintering) at a high temperature of 1500-2000°C Features: High purity (96%-99%), low activity, dense structure, strong high temperature resistance Typical applications: high-temperature kiln lining, refractory bricks, ceramic glazes, fused magnesia raw materials Fused magnesia Process: High-purity magnesia is produced by melting and cooling in an electric arc furnace (above 2800°C). Features: extremely high purity (above 99.5%), complete crystallization, optimal insulation and high temperature resistance. Typical applications: ultra-high temperature kilns, vacuum furnace linings, electronic component insulation materials, special ceramics

   2. Classification by purity (core index for industrial selection) Industrial grade (purity) 85%-95%): Mainly used in low-precision scenarios such as construction, rubber, and feed. High-purity grade (purity 96%-99%): used in ceramics, refractory materials, and electronic industries. Ultra-high purity grade (purity ≥99.9%): used in semiconductors, special glass, aerospace materials.

   3. Core industrial applications of magnesia (combined with high-temperature kilns/ceramics, etc.) 1. High-temperature kilns and refractory materials (core application areas) Function: Use its high melting point and corrosion resistance as a core component of kiln linings, refractory bricks, and castables. Specific scenarios: Ceramic kilns: support the kiln structure, resist high temperatures of 1200-1800°C and glaze corrosion. Metal smelting kilns: refractory linings for steelmaking converters and non-ferrous metal smelting furnaces. Special kilns: high-temperature resistant components for vacuum furnaces, sintering furnaces, and glass kilns. Selection points: Give priority to dead-burned magnesium oxide (96%). Above purity) or fused magnesium oxide, attention should be paid to "sintered density" (≥3.3g/cm³) and "temperature resistance stability" (no high temperature creep)

   2. Ceramics and powder materials Function: used as a flux and sintering aid for ceramic bodies, or directly made into magnesium oxide ceramics Specific applications: Structural ceramics: Magnesium oxide ceramics have high hardness, high temperature resistance, and insulation, and are used for high temperature valves and sensor housings Electronic ceramics: used as insulating substrates for capacitors and inductors (requires ultra-high purity magnesium oxide). Ceramic glazes: adjust the fluidity and gloss of the glaze, and improve the corrosion resistance of the glaze. Selection points: Use 96%-98% dead-fired magnesium oxide for the ceramic body. Electronic ceramics must be ≥99.9% ultra-high purity grade. Pay attention to the "particle size distribution" (D50=5-20μm, avoid agglomeration) 3. Other industrial scenarios Environmental protection field: as a neutralizing agent for acidic wastewater treatment (alkaline oxide reacts with acid to form magnesium salt), flue gas desulfurization agent. Chemical industry: as a flame retardant filler for plastics and rubber (decomposition endothermic, inhibiting combustion), catalyst carrier. Medical field: high-purity magnesium oxide can be used as an antacid (neutralizing gastric acid) and laxative. Construction field: mixed with magnesium chloride to make magnesite cement, which is used for fireproof boards and partition boards (mainly light-burned magnesium oxide). 4. Key points of industrial selection and supplier evaluation (Practical Guide) 1. Core selection indicators (sorted by priority) Purity: determined according to the application scenario (such as high-temperature kilns requiring ≥96%, electronic ceramics requiring ≥99.9%) Calcining temperature/process: heavy firing (above 1500°C) vs light firing (700-1000°C), heavy firing/electrofusion process must be selected for high temperature scenarios Activity/ Specific surface area: Refractory materials need low activity (specific surface area <5m²/g), adsorption/reaction scenarios require high activity (specific surface area >30m²/g) Impurity content: focus on Fe₂O₃, SiO₂, CaO (≤1%). Excessive impurities will reduce high temperature resistance and insulation. Physical form: powder (particle size distribution), block (sintered density), ceramic piece (density) 2. Key dimensions for supplier evaluation Production capacity: Whether it has high-temperature calcination (kilns above 1500°C) and electrofusion equipment, and whether the annual production capacity matches the purchase volume Quality control: whether third-party testing reports are provided (such as SGS, ICP-MS to detect purity and impurities), and whether it has passed ISO9001 certification Industry cases: whether there are cooperation cases in high-temperature kilns and ceramic industries (such as providing kiln refractory materials to a ceramics factory) Customization ability: Can the purity, particle size, and form be adjusted according to demand (such as customizing powders and molded ceramic parts with specific particle sizes) Cost and delivery: The unit price of dead-burned magnesium oxide is usually 8,000-15,000 yuan/ton, and fused magnesia is ≥30,000 yuan/ton. The cost-effectiveness and delivery cycle need to be compared. 3. Common misunderstandings and pitfalls: Confusing "light burning" with "light burning" "Re-burning": Misuse of light-burned magnesium oxide in high-temperature scenes will cause shrinkage and cracking at high temperatures due to excessive activity. Ignore the impact of impurities: Excessive Fe₂O₃ will reduce the whiteness and insulation of ceramics, and excessive CaO will cause melting loss at high temperatures. Look only at purity and not at the process: at the same purity, the high-temperature resistance of fused magnesium oxide is much better than that of dead-burned magnesium (the crystal structure is more stable).

   5. Summary Magnesium oxide is a "all-rounder" in the industrial field, and its core value lies in High-temperature stability and chemical inertness are irreplaceable especially in high-temperature kilns, ceramics, refractory materials and other scenarios. The key to selection is to determine the category (light burning/heavy burning/electric fusion) based on the operating temperature (such as whether it exceeds 1500°C) and accuracy requirements (such as purity, insulation), and then verify the reliability through the supplier's process capabilities, test reports, and industry cases.