Lost magnesium oxide can be used in non-critical areas such as soil improvement, environmental desulfurization, wastewater treatment, and low-strength building material filling. Its residual alkalinity and magnesium content still have some utilization value.
1. Agriculture: Acidic Soil Conditioner
The magnesium hydroxide and basic magnesium carbonate contained in spent magnesium oxide are weakly alkaline, which can neutralize acidic soil and adjust the pH value. Simultaneously, it slowly releases magnesium ions, supplementing the nutrients needed by plants and improving the crop growth environment. Suitable for tea gardens, orchards, and other areas where long-term use of chemical fertilizers has led to soil acidification.
Recommended dosage: 50-100 kg per acre, mix thoroughly after tilling, let stand for 1 week before sowing.
2. Environmental Protection: Flue Gas Desulfurization and Wastewater Treatment
In industrial flue gas treatment, spent magnesium oxide can still be used as a desulfurizing agent, absorbing SO₂ to generate magnesium sulfate; it can be used to neutralize acidic industrial wastewater, adjust pH, and promote the precipitation of heavy metal ions; although its activity is lower than fresh MgO, its low cost makes it suitable for scenarios where reaction efficiency requirements are not high.
It can be used in conjunction with lime to improve treatment stability and reduce reagent consumption.
3. Building Materials: Filler for Low-Grade Products
A small amount of spent magnesium oxide can be added as a filler component to non-load-bearing wall panels, blocks, or road base materials;
The dosage needs to be controlled (recommended <15%), and it should be used in conjunction with an activity activator (such as magnesium chloride solution) to improve cementitious properties; it is suitable for temporary buildings or backfilling projects where strength requirements are not high.
It is prohibited for use in high-performance materials such as structural concrete and fireproof boards.
4. Other Potential Uses
Horticultural substrate conditioning: Mixed into seedling soil to prevent the substrate from becoming too acidic;
Livestock bedding additive: Adding a small amount can absorb moisture and deodorize, improving the environment of livestock pens;
Teaching and experimental materials: Used in middle school chemistry classrooms to demonstrate acid-base reactions or precipitation experiments.
It is recommended to conduct small-scale trials before any reuse to verify actual effectiveness and compatibility.
