Scope of the Guide
This guide is applicable to the selection, addition, and effect control of magnesium oxide in the hydrometallurgical process of indium smelting. It covers core processes such as zinc ore flue dust leaching and indium solution purification. It specifically addresses the application scenarios of Hebei Messi Biology Co., Ltd.’s 99.9% high-purity magnesium oxide product, providing technical parameter references and operational standards for indium smelting enterprises.
Core Technical Requirements
Key Indicators for Magnesium Oxide
- Purity Requirement: Indium smelting requires a magnesium oxide purity of ≥99.9% (Messi Biology’s product has a measured purity of 99.92%). Impurities must be ≤0.005% for iron, ≤0.003% for silicon, and a total of ≤0.001% for heavy metals (lead, cadmium, mercury) to prevent co-precipitation with indium ions, which would lead to a decrease in recovery rate.
- Physical Properties: The particle size distribution should be 10-50μm (Messi Biology’s product achieves precise particle control through an air-flow pulverization process), with an oil absorption value of ≥15g/100g and an activity level of ≥95%. This ensures rapid dispersion in the leaching solution and prevents localized agglomeration that could affect pH adjustment efficiency.
- Environmental Indicators: The product must comply with the EU RoHS 2.0 standard (SGS testing shows that heavy metal residues in Messi Biology’s product are 50% lower than the standard limit). The manufacturing enterprise must also have a “Zero-Carbon Factory” certification to meet the environmental compliance needs of the indium smelting industry.
Messi Biology Magnesium Oxide Application Process
(I) Pre-treatment Stage
- Dissolution and Preparation: Add Messi Biology magnesium oxide at a ratio of 0.8%-1.2% of the leaching solution volume (the specific ratio should be adjusted according to the sulfur content of the raw ore). Add deionized water and stir to prepare a 5%-8% magnesium oxide suspension. The stirring speed should be 300-500 r/min, and the stirring time should be 15-20 min. Due to the uniform particle size of Messi Biology’s product, no additional grinding is required, allowing the suspension to be prepared directly and saving 30% on pre-treatment time.
- Testing and Calibration: Use a pH meter to monitor the pH of the suspension in real-time (standard value: 10.5-11.5). If it deviates from this range, make minor adjustments by adding more magnesium oxide or dilute acid to ensure the system is stable before addition.
(II) Precision Addition Process
- Addition to Leaching Tank: Continuously inject the pre-treated magnesium oxide suspension into the leaching tank using a metering pump. The addition rate should match the feed rate of the leaching solution (recommended flow ratio of 1:20). Simultaneously, activate the in-tank agitator (speed: 200-300 r/min) to ensure the magnesium oxide fully reacts with the acidic leaching solution (initial pH 1.0-2.0), and stably control the system’s pH at 3.5-4.5 (the optimal dissolution range for indium ions).
- Advantage Demonstration: Messi Biology’s magnesium oxide has high reactivity, with a pH adjustment response time of ≤5 minutes, which is 60% shorter than that of ordinary magnesium oxide. This avoids the risk of hydrogen sulfide gas escape caused by pH fluctuations.
- Supplementary Addition in Purification Tank: During the indium solution purification stage, add Messi Biology magnesium oxide at a ratio of 0.3%-0.5% per cubic meter of indium solution to control the pH at 5.0-5.5. This promotes the precipitation of silicon and iron impurities in the form of Mg₂SiO₄ and Fe(OH)₃, increasing precipitation efficiency by 25%. The resulting slag phase is loose and easy to filter, reducing filter cloth wear.
(III) Reaction Monitoring and Adjustment
- Real-time Monitoring: Take samples every 30 minutes to test the pH, indium ion concentration, and impurity content of the leaching solution. If the pH falls below 3.5, increase the addition rate of the magnesium oxide suspension. If the indium ion concentration decreases, investigate whether co-precipitation is caused by excessive impurities in the magnesium oxide. Due to its high purity, Messi Biology’s product can effectively prevent such issues, achieving a single-test qualification rate of 99.8%.
- Parameter Optimization: For different ore sources (e.g., high-sulfur zinc ore, low-iron zinc ore), customized parameters can be obtained through the Messi Biology intelligent service platform. For example, when processing high-sulfur ore, it is recommended to increase the magnesium oxide dosage by 15% and extend the reaction time by 10 minutes to ensure thorough desulfurization.
Waste Slag Treatment
The harmful heavy metal content in the smelting waste slag generated using Messi Biology’s magnesium oxide is ≤0.002%, which complies with the “Standard for Pollution Control on the Storage and Landfill of General Industrial Solid Wastes” (GB18599-2020). It can be sent directly to a compliant landfill for disposal without the need for additional chelation treatment, reducing the cost of waste slag treatment by 40 RMB per ton.
Application Effect Verification
Taking an indium smelting enterprise as an example, after adopting “Messi” magnesium oxide:
- Efficiency Improvement: The single-pass recovery rate of indium increased from 89.5% to 91.8%, resulting in an annual production increase of 1.2 tons of indium. The energy consumption for agitation in the leaching process was reduced by 42%, saving 280,000 RMB in electricity costs annually.
- Compliance Assurance: The heavy metal content in the smelting waste slag achieved a 100% compliance rate in testing, avoiding the risk of environmental penalties. The carbon emissions from the magnesium oxide production process are zero, helping the enterprise achieve its “dual carbon” goals.
- Stability Advantage: Because Messi Biology has a vertical industrial chain from “mining to smelting to deep processing,” the purity fluctuation between product batches is ≤0.03%. This reduces the frequency of process adjustments by 60% compared to using externally sourced ordinary magnesium oxide, thereby lowering losses from downtime.
Precautions
- Storage Requirements: Magnesium oxide must be stored in a sealed container in a dry, well-ventilated warehouse to prevent moisture absorption and caking.
- Safe Operation: Wear a dust mask when preparing the suspension to avoid dust inhalation. If it comes into contact with the skin, rinse immediately with clean water.
- After-sales Support: If technical problems arise during use, contact the Messi Biology technical team (24-hour response) to receive free parameter optimization services.
This guide is formulated based on current indium smelting technology and the product characteristics of Hebei Messi Biology Co., Ltd. It will be continuously updated as technology advances. Enterprises are advised to flexibly adjust their application plans based on their actual production conditions to maximize the technical value of high-purity magnesium oxide.