SIST EN 13971:2020

Carbonate and silicate liming materials - Determination of reactivity - Potentiometric titration method with hydrochloric acid

This document specifies a method for the determination of the speed and effectiveness of the neutralizing potential of calcium carbonate, calcium magnesium carbonate and calcium magnesium silicate liming materials by potentiometric titration with hydrochloric acid.
For liming materials coarser than 1 mm, it is essential to prepare the sample of a liming material by following exactly the description of Annex A.
This method is applicable only to liming materials with a maximum particle size of 6,3 mm.
The type of liming material can be identified according to EN 14069 and the particle size can be determined according to EN 12948.

Carbonatische und silikatische Kalke - Bestimmung der Reaktivität - Potentiometrisches Titrationsverfahren mit Salzsäure

Dieses Dokument legt ein Verfahren für die Bestimmung der Geschwindigkeit und Wirksamkeit des Neutralisationspotentials von Calciumcarbonat-, Calcium-Magnesium-Carbonat- sowie silikatischen Kalkdüngern durch potentiometrische Titration mit Salzsäure fest.
Für Kalkdünger, die grobkörniger als 1 mm sind, ist es wichtig, die Vorbereitung der Kalkdüngerprobe sorgfältig nach der in Anhang A angegebenen Beschreibung durchzuführen.
Dieses Verfahren gilt nur für Kalkdünger mit einer Korngröße von höchstens 6,3 mm.
Der Typ des Kalkdüngers kann nach EN 14069 identifiziert und die Korngröße nach EN 12948 bestimmt werden.

Amendements minéraux basiques carbonatés et silicatés - Détermination de la réactivité - Méthode par titrage potentiométrique à l'acide chlorhydrique

Le présent document spécifie une méthode pour déterminer la vitesse et l'efficacité du potentiel de neutralisation des carbonates de calcium, carbonates de calcium et de magnésium et silicates de calcium et de magnésium utilisés comme amendements minéraux basiques, par titrage potentiométrique à l’acide chlorhydrique.
Pour les amendements minéraux basiques plus grossiers que 1 mm, il est essentiel de préparer l’échantillon d’amendements minéraux basiques en suivant précisément la description en Annexe A.
La présente méthode s'applique seulement aux amendements minéraux basiques dont la taille des particules ne dépasse pas 6,3 mm.
Le type d’amendement minéral basique peut être identifié conformément à l’EN 14069 et la taille des particules peut être déterminée conformément à l’EN 12948.

Karbonatna in silikatna sredstva za apnjenje - Določevanje reaktivnosti - Potenciometrijska titracijska metoda s klorovodikovo kislino

General Information

• Status: Published
• Public Enquiry End Date: 03-Apr-2019
• Publication Date: 23-Sep-2020
• ICS: 65.080 - Fertilizers
• Technical Committee: KAT - Soil quality
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 07-Sep-2020
• Due Date: 12-Nov-2020
• Completion Date: 24-Sep-2020
• Ref Project: EN 13971:2020 - Carbonate and silicate liming materials - Determination of reactivity - Potentiometric titration method with hydrochloric acid

Relations

• Replaces: SIST EN 13971:2013 - Carbonate and silicate liming materials - Determination of reactivity - Potentiometric titration method with hydrochloric acid
• Effective Date: 01-Nov-2020

Overview

EN 13971:2020 (CEN) specifies a laboratory method to determine the reactivity - i.e., the speed and effectiveness of the neutralizing potential - of carbonate and silicate liming materials. The method uses potentiometric titration with hydrochloric acid (HCl) to quantify acid consumption during a controlled reaction period, providing an indicator of how quickly and effectively liming materials will neutralize soil acidity.

Key topics and technical requirements

• Scope: Applies to calcium carbonate, calcium magnesium carbonate and calcium magnesium silicate liming materials with a maximum particle size of 6.3 mm.
• Sample preparation: Follow EN 1482-2 for sampling and EN 12048 for drying. For materials coarser than 1 mm, the test portion must be prepared exactly as described in Annex A of EN 13971:2020.
• Method principle: Decomposition of carbonates/silicates by HCl with potentiometric monitoring (pH electrode). Acid consumption over a defined time is a direct measure of reaction rate.
• Procedure: Includes both automatic and manual titration routes. Key steps include pH electrode calibration (pH 2.0 and 4.0 buffers), controlled addition of 5.0 mol·L⁻¹ HCl, stirring, timed titration (record acid consumed after 10 minutes) and replicate determinations.
• Apparatus and reagents: pH meter and electrode, burette (motor-driven for automatic titration), magnetic stirrer, silicone defoamer (if foaming), and analytical-grade reagents (notably 5.0 mol/L HCl and a calcium carbonate reference).
• Silicate materials: After titration, silicate suspensions require filtration and chemical analysis of calcium and magnesium per EN 13475 and EN 12947.
• Reporting and precision: The standard defines expression of results, repeatability/reproducibility performance data and required test-report items (including confirmation of particle-size proportional weighing per Annex A).

Applications and users

• Quality control and product classification for fertilizer and liming material manufacturers.
• Independent testing laboratories performing reactivity testing for suppliers, certification bodies and regulators.
• Agronomists, soil scientists and extension services using reactivity data to estimate field behaviour and to compare products (results correlate with soil incubation methods).
• Useful where neutralizing value, reaction rate, and particle size influence agronomic recommendations and product labeling.

Related standards

• EN 14069 - Identification of liming material type
• EN 12948 - Determination of particle size distribution (sieving)
• EN 1482-2 - Sampling and sample preparation
• EN 12048 - Moisture determination
• EN 12945 / EN 12947 / EN 13475 - Complementary chemical analyses

Keywords: EN 13971:2020, potentiometric titration, liming materials, reactivity, hydrochloric acid, carbonate liming, silicate liming, neutralizing potential, Annex A, particle size, CEN.

Standards Content (Sample)

SLOVENSKI STANDARD
01-november-2020
Nadomešča:
SIST EN 13971:2013
Karbonatna in silikatna sredstva za apnjenje - Določevanje reaktivnosti -
Potenciometrijska titracijska metoda s klorovodikovo kislino
Carbonate and silicate liming materials - Determination of reactivity - Potentiometric
titration method with hydrochloric acid
Carbonatische und silikatische Kalke - Bestimmung der Reaktivität - Potentiometrisches
Titrationsverfahren mit Salzsäure
Amendements minéraux basiques carbonatés et silicatés - Détermination de la réactivité
- Méthode par titrage potentiométrique à l'acide chlorhydrique
Ta slovenski standard je istoveten z: EN 13971:2020
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 13971
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2020
EUROPÄISCHE NORM
ICS 65.080 Supersedes EN 13971:2012
English Version
Carbonate and silicate liming materials - Determination of
reactivity - Potentiometric titration method with
hydrochloric acid
Amendements minéraux basiques carbonatés et Carbonatische und silikatische Kalkdünger -
silicatés - Détermination de la réactivité - Méthode par Bestimmung der Reaktivität - Potentiometrisches
titrage potentiométrique à l'acide chlorhydrique Titrationsverfahren mit Salzsäure
This European Standard was approved by CEN on 14 March 2020.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 13971:2020 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Principle . 5
5 Apparatus . 6
6 Reagents . 6
7 Preparation of the test sample . 7
8 Procedure. 7
8.1 Automatic titration . 7
8.1.1 Calibration . 7
8.1.2 Determination . 8
8.2 Manual titration . 8
8.2.1 Calibration . 8
8.2.2 Determination . 9
8.3 Determination of neutralizing value . 9
9 Expression of results . 10
9.1 Carbonate liming materials . 10
9.2 Silicate liming materials . 10
10 Precision . 11

10.1 Repeatability . 11
10.2 Reproducibility . 11
10.3 Precision data for carbonate liming materials . 11
10.4 Precision data for silicate liming materials . 12
11 Test report . 13
Annex A (normative) Preparation of the test portion of liming materials coarser than 1 mm . 14
A.1 General . 14
A.2 Calculation of mass fractions retained on the test sieves . 14
A.3 Calculation of the mass of each sieving fraction to be incorporated in the test portion . 14
Annex B (normative) Arrangement of the test apparatus . 15
Bibliography . 17

European foreword
This document (EN 13971:2020) has been prepared by Technical Committee CEN/TC 260 “Fertilizers
and liming materials”, the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by March 2021, and conflicting national standards shall
be withdrawn at the latest by March 2021.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 13971:2012.
The following changes have been made to the former edition:
a) Clause 1, Scope enlarged by adding an indication of the special sample preparation for liming
materials coarser than 1 mm;
b) Clause 11, Test report enlarged by adding a requirement on confirmation that partical size
proportional weighing of the test sample was performed according to Annex A;
c) Clause 3, Terms and definitions editorially revised;
d) Clause 10, Precision editorially revised.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Introduction
The results obtained by this method can be used to estimate the behaviour of the liming material in the
soil. The results show a good correlation with the results obtained by a soil incubation method (see [1]
to [6]). Regarding the precision of the method, the results are not used to declare a value, but to classify
the different product groups.
1 Scope
This document specifies a method for the determination of the speed and effectiveness of the
neutralizing potential of calcium carbonate, calcium magnesium carbonate and calcium magnesium
silicate liming materials by potentiometric titration with hydrochloric acid.
For liming materials coarser than 1 mm, it is essential to prepare the sample of a liming material by
following exactly the description of Annex A.
This method is applicable only to liming materials with a maximum particle size of 6,3 mm.
The type of liming material can be identified according to EN 14069 and the particle size can be
determined according to EN 12948.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 1482-2, Fertilizers and liming materials — Sampling and sample preparation — Part 2: Sample
preparation
EN 12048, Solid fertilizers and liming materials — Determination of moisture content — Gravimetric
method by drying at (105 ± 2) °C (ISO 8190:1992 modified)
EN 12944-3, Fertilizers and liming materials — Vocabulary — Part 3: Terms relating to liming materials
EN 12945, Liming materials — Determination of neutralizing value — Titrimetric methods
EN 12947, Liming materials — Determination of magnesium content — Atomic absorption spectrometric
method
EN 12948, Liming materials — Determination of size distribution by dry and wet sieving
EN 13475, Liming materials — Determination of calcium content — Oxalate method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 12944-3 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
4 Principle
Decomposition of carbonates and silicates with acids according to the following reactions:
+ 2+
+ 2 H → Me + H O + CO
MeCO3 2 2
+
MeSiO + 2 H → Me(OH) + SiO
4 2 2
Titration under stable pH conditions either with an automatic titration apparatus or a manual method.
The acid consumption during a given time is a direct measure of the reaction rate of the liming
materials being tested.
5 Apparatus
Usual laboratory apparatus and, in particular, the following:
5.1 pH meter, with electrode.
5.2 Burette.
NOTE Used only for 5,0 mol/l hydrochloric acid (6.2).
5.2.1 50 ml motor driven burette, for automatic titration.
A pH stat function is recommended.
5.2.2 50 ml burette, for manual titration.
5.3 250 ml glass beaker, with an inner diameter of 65 mm.
5.4 Magnetic stirrer, with centring mark for the 250 ml glass beaker.
5.5 Magnetic stirrer rod, (9 ± 1) mm diameter times (50 ± 1) mm length, with central ring.
5.6 Stop-watch.
5.7 Filter paper, acid-proof, medium filtration speed, average retention capacity about 5 μm to
12 μm.
6 Reagents
All reagents shall be of recognized analytical grade.
6.1 Hydrochloric acid solution, mass fraction, w(HCl) = 25 %.
6.2 Hydrochloric acid, standard volumetric solution, c(HCl) = 5,0 mol/l.
6.3 Calcium carbonate, precipitated, mass fraction, w(CaCO ) = of at least 99 %.
Precipitated calcium carbonate (PCC) is from crystalline origin. Commercial PCC for analysis is granted
for its chemical characteristics. However, physical characteristics are not granted. The use of a highly
reactive PCC, such as commercial PCC from VWR / Prolabo / BDH, reference GPR, Rectapur, Ref
1)
22296.294, Molar mass 100,09 which will consume 15 ml after 15 min, is recommended.
6.4 Silicone defoamer.
6.5 Standard buffer solution, pH = 2,0, commercial solution.
NOTE This has a limited life.
6.6 Standard buffer solution, pH = 4,0, commercial solution.
NOTE This has a limited life.
1) This substance is an example of a suitable product available commercially. This information is given for the
convenience of users of this document and does not constitute an endorsement by CEN of this product.
7 Preparation of the test sample
7.1 Prepare the sample of the liming material in accordance with EN 1482-2.
7.2 Dry the test sample in accordance with EN 12048. Record the result for information only.
7.3 Use the dried test sample without further preparation, e.g. grinding.
7.4 Weigh a 5,0 g test portion of the dried sample to the nearest 0,01 g. For liming materials coarser
than 1 mm, the test portion shall be prepared in accordance with Annex A.
8 Procedure
8.1 Automatic titration
8.1.1 Calibration
8.1.1.1 Calibrate the pH meter (5.1) with two standard buffer solutions, pH 2,0 (6.5) and pH 4,0
(6.6) to exactly the indicated values. The pH electrode shall react quickly.
Check the sluggishness of the electrode and if necessary, clean it carefully with hydrochloric acid (6.2)
and re-calibrate with the standard buffer solutions.
Checking and cleaning is more frequently required for liming materials containing clay.
It is recommended to flush the acid introduction pipe between each sample for slow reacting samples.
8.1.1.2 Adjust the motor driven burette (5.2.1) to the position “continuous working” and a standard
flow rate of 35 ml/min to 38 ml/min.
NOTE Wide deviations in the flow rate adversely affect the results obtained.
8.1.1.3 Place the glass beaker (5.3) centrally on the magnetic stirrer (5.4). Ad
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