取样材料中和值的测定滴定法

[中文适用范围]： 本文件规定了测定石灰材料中和值（NV）的两种方法。 方法A适用于除硅酸盐石灰材料之外的所有石灰材料。 注 1：硬石灰材料的例子是石灰石和白云石。 软石灰材料的例子有白垩、泥灰和生石灰。 方法B适用于所有石灰材料。 这两种方法都没有正确考虑 P2O5 含量超过 3% 的材料的潜在中和值。 为了对 P2O5 含量超过 3% 的产品进行更准确的农艺评估，使用 EN 14984[8] 来确定浸灰效率。 注 2：P2O5 含量的测定可采用 ISO 6598 和 ISO 7497 中描述的方法。 有关 P 分析的更多信息参见参考文献 [5] 和 [6]。 注 3：碳酸盐消耗 H+ 并去除溶液中的酸度，随后分解为 H2O 和 CO2。 正磷酸盐的形式可以消耗 H+，但不会解离成消除酸度的分子形式。 酸度用碱进行反滴定，导致 NV 被低估。 [外文原描述]： 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 % P 2 O 5 . For a more accurate agronomic assessment of products containing more than 3 % P 2 O 5 , EN 14984 [8] 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 P 2 O 5 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 H 2 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.