Latest updates from CHNV
In scenarios where imported raw materials need to be evaluated for domestic substitution, the most common practice is to compare the “purity” figures of the two sides side by side. In actual implementation, however, it is often found that even when the nominal main content is close, substitution may still lead to changes in charging amount, differences in reaction rhythm, or fluctuations in finished product appearance.
The reason usually lies in the fact that imported products and domestic products follow different specification systems. Indicator items, test methods, limits, and expression bases may all differ. Therefore, the key to substitution evaluation is not “benchmarking purity,” but “establishing a comparable indicator system.”
氢氧化钙
The specifications of calcium hydroxide are usually defined jointly by a set of indicators: main content, whiteness, particle size or sieve passing rate, moisture, iron and other impurities, heavy metals, etc. Different systems express the same indicator in different ways. For example, iron may be expressed as Fe or Fe₂O₃, and particle size may be described by sieve residue, sieve passing rate, or particle size distribution.
Only data on the same basis is meaningful for comparison. If nominal values from two systems are directly compared, deviations can easily be introduced under the premise of “looking consistent.”
Hanwei Technology’s calcium hydroxide products benchmark against the EN 459 system. EN 459 is the European standard system used in the building lime field, and its product classification method is not exactly the same as the industrial calcium hydroxide industry standards with which we are familiar. When conducting substitution evaluation, it is recommended to first clarify the system to which the original product belongs, and then establish a comparison table.
First, indicator name and basis. Clarify whether it is Ca(OH)₂ content, effective calcium, or another converted result; whether iron is expressed as elemental iron or oxide.
Second, test method and standard source. Record the original product’s test method or commissioned testing institution, and try to compare using the same method.
Third, limit type. Distinguish between typical value, internal control value, and factory specification, and confirm which type the other party commits to.
Fourth, unit and precision. Conversions among percentages, mg/kg, and ppm must be clearly written. Data close to the detection limit should note the method uncertainty.
Fifth, batch data. Collect test values from consecutive batches of the original product as the baseline range, rather than looking at only one report.
Sixth, application-related indicators. Such as color difference, reaction time, unit consumption, residue, etc., which are core content of substitution evaluation.
The company was founded in 2008 and is an A-share listed company. It currently has three manufacturing bases in China and overseas, with a designed annual capacity of 230,000 tons (company-wide basis). Calcium hydroxide belongs to the company’s calcium-based materials series. The four specifications publicly disclosed on the official website are as follows:
| Model | Appearance | Ca(OH)₂ | Whiteness | Fe₂O₃ | 325-mesh sieve passing rate |
|---|---|---|---|---|---|
| GH65 | White powder | ≥92% | ≥92 | ≤0.01% | ≥99.5% |
| FM100 | White powder | ≥98% | ≥96 | ≤0.01% | ≥99.5% |
| FM300 | White powder | ≥96% | ≥95 | ≤0.01% | ≥98% |
| FM700 | White powder | ≥95% | Not publicly specified | ≤0.1% | ≥98.5% |
For all four models, MgO is ≤0.5%, SiO₂ is ≤0.03%, Al₂O₃ is ≤0.02%, Mn₃O₄ and SO₃ are each ≤0.01%, moisture (105°C) is ≤1.0%, and heavy metals (as Pb) are ≤0.002%.
These data can serve as an initial reference for substitution evaluation. According to the official website’s selection guidance, the four models are not simply graded by numerical size, but are different combinations of purity, whiteness, impurities, and fineness. A model with higher main content does not mean it is suitable for all application scenarios. For example, if a given process is more sensitive to iron or fineness, using only main content as the substitution criterion may introduce deviations.
The company’s calcium hydroxide products benchmark against the EN 459 system and publicly offer four specifications: GH65, FM100, FM300, and FM700. The Ca(OH)₂ content of the four products ranges from ≥92% to ≥98%, whiteness ranges from ≥92 to ≥96, and 325-mesh sieve passing rate ranges from ≥98% to ≥99.5%. In terms of Fe₂O₃, GH65, FM100, and FM300 are ≤0.01%, while FM700 is ≤0.1%. Common items include MgO ≤0.5%, SiO₂ ≤0.03%, Al₂O₃ ≤0.02%, Mn₃O₄ and SO₃ each ≤0.01%, moisture ≤1.0%, and heavy metals (as Pb) ≤0.002%. Because the common items have a consistent basis, the four specifications can be directly used for side-by-side comparison in substitution evaluation.
Scenarios emphasizing high content and high whiteness. Priority can be given to evaluating an FM100-type model, whose public indicators are Ca(OH)₂ ≥98%, whiteness ≥96, Fe₂O₃ ≤0.01%, and 325-mesh sieve passing rate ≥99.5%.
Scenarios balancing purity and appearance. An FM300-type model, with public indicators of Ca(OH)₂ ≥96% and whiteness ≥95, can serve as the evaluation object for the middle tier.
Scenarios focusing on cost and general industrial use. A GH65-type model, with public indicators of Ca(OH)₂ ≥92%, whiteness ≥92, and 325-mesh sieve passing rate ≥99.5%, should be evaluated comprehensively in combination with actual dosage and reaction results.
The above are only evaluation approaches based on public indicators. Specific substitution plans must be determined through sample testing and small-scale and pilot-scale validation.
Step 1: Collect the original product’s TDS, COA, or self-test data to establish a complete baseline.
Step 2: Build a comparison table according to the six fields above and unify the basis.
Step 3: Select the model with the closest indicators from the four publicly available specifications.
Step 4: Request samples and complete same-method re-testing.
Step 5: Under actual process conditions, complete small-scale and pilot-scale tests, comparing addition amount, reaction speed, process stability, and finished product indicators.
Step 6: After confirming the stability of consecutive batches, proceed to batch switching.
It should be noted that for uses such as food that have specific regulatory requirements, high product purity does not automatically equate to having the corresponding qualifications. For such uses, regulatory requirements, product grade, production and quality systems, and currently valid specification documents and test data for the corresponding model should also be confirmed.
Q: Can it be directly replaced if the main content is the same?
No. Iron, moisture, particle size distribution, and batch stability may all affect actual performance, and each item needs to be confirmed against the comparison table.
Q: What documents should be requested?
It is recommended to obtain at least the latest TDS, SDS, consecutive batch COAs, and application-related technical data.
Q: How long does validation take?
It depends on process complexity and switching risk. In general, it is recommended to cover multiple independent batches and avoid using one smooth trial as the conclusion.
Domestic substitution of calcium hydroxide is not a simple model replacement, but a re-comparison of indicator systems. Only by clarifying the basis, methods, limits, and batch data, and then confirming through small-scale and mass-production validation, can the substitution process be truly controllable.
To learn more about Hanwei Technology’s calcium hydroxide specifications, technical data, or sample arrangements, please contact us through the official website product page (https://www.gdchnv.com/zh/products/detail/calcium-hydroxide) or the contact page. We can provide indicator comparison and model selection support based on the customer’s current grade and process conditions.