ISO 20978:2020 石灰材料 中和值的测定 滴定法

标准编号：ISO 20978:2020

中文名称：石灰材料 中和值的测定 滴定法

英文名称：Liming material — Determination of neutralizing value — Titrimetric methods

发布日期：2020-05

标准范围

This document specifies two methods for the determination of the neutralizing value (NV) of liming
materials.
Method A is applicable to all liming materials except silicate liming materials.
NOTE 1 Examples of hard liming materials are limestone and dolomite. Examples of soft liming materials are chalk, marl and burnt lime.
Method B is applicable to all liming materials.
Neither method correctly takes into account the potential neutralizing value of material containing
more than 3 % P₂ O₅ . For a more accurate agronomic assessment of products containing more than 3 %  P₂ O₅ , EN 14984 is used to determine the liming efficiency.
NOTE 2 The methods described in ISO 6598 and ISO 7497 can be used for the determination of P₂  O₅ content. Further information on P analyses is given in References [5] and [6].
NOTE 3 Carbonate consumes H⁺ and removes acidity in solution with subsequent dissociation to H₂ O and CO ₂ . Forms of orthophosphate can consume H⁺ but are not dissociated to molecular forms that remove acidity. The acidity is back titrated with alkali causing an underestimation of NV.

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