1、BSI Standards PublicationBS EN 16357:2013Carbonate liming materials Determination of reactivity Automatic titration methodwith citric acidBS EN 16357:2013 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 16357:2013.The UK participation in its preparation was entr
2、usted to TechnicalCommittee CII/37, Fertilisers and related chemicals.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplicat
3、ion. The British Standards Institution 2013. Published by BSI StandardsLimited 2013ISBN 978 0 580 75379 4ICS 65.080Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on
4、31 August 2013.Amendments issued since publicationDate Text affectedBS EN 16357:2013EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 16357 August 2013 ICS 65.080 English Version Carbonate liming materials - Determination of reactivity - Automatic titration method with citric acid Amendements min
5、raux basiques carbonats - Dtermination de la ractivit - Mthode par titration automatique lacide citrique Carbonatische Kalke - Bestimmung der Reaktivitt - Automatisches Titrationsverfahren mit Citronensure This European Standard was approved by CEN on 29 June 2013. CEN members are bound to comply wi
6、th 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 Mana
7、gement 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 st
8、atus as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Mal
9、ta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2013 CEN All rights
10、 of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 16357:2013: EBS EN 16357:2013EN 16357:2013 (E) 2 Contents Page Foreword . 3 Introduction 4 1 Scope 5 2 Normative references . 5 3 Principle 5 4 Apparatus . 5 5 Reagents . 6 6 Sampling and sample pr
11、eparation 7 6.1 General . 7 6.2 Preparation of the test sample 8 6.3 Preparation of the test portion 8 7 Procedure . 8 7.1 General . 8 7.2 Calibrations 8 7.3 Measurement 10 7.4 Determination of neutralising value 11 7.5 Determination of MgO content 11 8 Calculation and expression of the results 11 9
12、 Precision . 12 9.1 Inter-laboratory tests . 12 9.2 Repeatability . 12 9.3 Reproducibility . 12 10 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 Cal
13、culation of the test portion to be weighed . 14 Annex B (normative) Arrangement of the test apparatus . 15 Bibliography 16 BS EN 16357:2013EN 16357:2013 (E) 3 Foreword This document (EN 16357:2013) has been prepared by Technical Committee CEN/TC 260 “Fertilizers and liming materials”, the secretaria
14、t 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 February 2014, and conflicting national standards shall be withdrawn at the latest by February 2014. Attention is drawn t
15、o the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following c
16、ountries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
17、 Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. BS EN 16357:2013EN 16357:2013 (E) 4 Introduction This method has been prepared to improve existing agricultural reactivity methods (see 1, 2, 3, 4 and 5) for carbonate liming materials: duratio
18、n, accuracy, representativeness, closer from soil conditions, automation. Attention is drawn to the following critical steps: identification of the liming material type (influence on precision data); size distribution (influence on test portion preparation and amount); calibration of pH electrode (i
19、nfluence on titrators pH adjustments); pH stat programme setting (influence on accuracy of added amounts of citric acid solution); suitability of PCC used to check calibration; stirring device (provides homogeneousness without grinding); additional uncertainty with neutralising value and MgO content
20、 determination. BS EN 16357:2013EN 16357:2013 (E) 5 1 Scope This European Standard specifies a method for the determination of the reactivity of calcium carbonate and calcium magnesium carbonate liming materials. It assesses the speed and effectiveness of their neutralising potential by automatic ti
21、tration with citric acid. This method is applicable only to liming materials with a maximum particle size of 6,3 mm determined according to EN 12948. NOTE For marble dolomite (BET procedure according to ISO 9277 below 500 m2/kg), see EN 14984. 2 Normative references The following documents, in whole
22、 or in part, are normatively referenced in this document and are indispensable for its application. 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 materi
23、als 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, modified) EN 12945, Liming materials Determination of neutralizing value Titrimetric methods EN 1
24、2948, Liming materials Determination of size distribution by dry and wet sieving EN ISO 3696, Water for analytical laboratory use Specification and test methods (ISO 3696) 3 Principle Limited decomposition of carbonates in a given time with acid according to the following reaction: 2223COOHMeH2MeCO
25、+Titration under stable pH conditions (pH 4,5) with an automatic titration apparatus. The citric acid consumption during a given time (15 min) is a direct measure for the reaction of the liming materials being tested. 4 Apparatus Usual laboratory apparatus and, in particular, the following: 4.1 pH m
26、eter with electrode. This instrument is generally included in the automatic motor driven burette device. 4.2 Automatic motor driven burette, capacity 20 ml. This kind of burette is generally equipped with all necessary accessories such as pH regulation programme (pH stat), automatic refilling device
27、, pH electrode, continuous pH measurement and propeller stirring device. Though a propeller stirring device is preferred, a magnetic stirring device (4.7) may be used, provided the central ring of the stirrer rod is thick enough and does not lead to grind the tested material. Make sure the rotation
28、speed of the stirrer rod is fast enough to make homogeneous dispersion in the beaker. If not, increase the speed up to the necessary value. BS EN 16357:2013EN 16357:2013 (E) 6 The burette shall be able to deliver at least 0,05 ml of citric acid solution (5.3) per second. This is to ensure the first
29、part of the reaction (pH dropping from initial pH value to target pH value (4,5) will not be a limiting factor for liming material dissolution speed). This figure is higher than the flow rate obtained with the fastest reaction observed in preliminary tests. The burette shall be able to deliver its w
30、hole content in at least 4 000 steps to ensure accuracy for low amount of citric acid solution (5.3). NOTE This condition is always fulfilled with modern titrators. All contemporary (less than 10 years old) titrators allow such accuracy: i.e. minimum step amount: 0,002 5 ml for a 10 ml burette, or 0
31、,012 5 ml for a 50 ml burette. This is sufficient, even for low amounts. However, this accuracy is obtained only if correct (minimal) step volume in titrator setup is specified. If not, the precision of the method will be altered. Use the burette only for the citric acid solution (5.3). For liming m
32、aterials coarser than 1 mm, use a 50 ml burette. For most of products, a 10 ml burette is sufficient. However, a 20 ml burette is necessary for highly reactive chalks and precipitated calcium carbonate. Because refilling takes a significant time, this can bias the results. If volumes higher than 10
33、ml are expected, do not use the automatic refilling possibility and use a 20 ml or a 50 ml burette. 4.3 Glass beaker, capacity 100 ml. For liming materials coarser than 1 mm, use a 200 ml beaker. Minimum diameter in case of magnetic stirring device (4.7): 50 mm. 4.4 Stop-watch. 4.5 Balance, capable
34、of weighing 10 g to the nearest 0,01 g. 4.6 Sample changer, optional. If occurring, a beaker of water (5.1) shall be inserted between two samples. 4.7 Magnetic stirring device, optional, see 4.2. Capable of minimum 500 min1speed rotation. Stirrer rod minimum length: 40 mm. 5 Reagents All reagents sh
35、all be of recognised analytical grade. 5.1 Water, according to EN ISO 3696, grade 2. 5.2 Mono hydrated citric acid, C6H8O7H2O, crystallised or powder, molar mass: 210,14 g. Do not use anhydrous citric acid having a different molar mass, which can partially hydrate when storing. 5.3 Citric acid solut
36、ion, = 457,17 g/l. Preferably, use a fresh home-made solution as described below. Under these conditions, the solution concentration is conventionally supposed to be equal to the necessary one, ca= 457,17 g pure citric acid per litre. BS EN 16357:2013EN 16357:2013 (E) 7 The solution may be used for
37、up to, at most, one month stored in a closed, dark glass vessel. If the solution has been stored more than one week, check its concentration by any means, for example by titration with a strong base (NaOH) solution of known concentration and report the result in the formula given in Clause 8. Weigh
38、500 g of mono hydrated citric acid (5.2) to the nearest 0,1 g. Pour it quantitatively into a 1 l measuring vessel. Rinse the weighing material and pour the rinsing water into the vessel in a way that it takes any acid stuck on the edge or on the bottom. Add about 500 ml of water (5.1) to the measuri
39、ng vessel. Heat the vessel until full dissolution (temperature about 80 C). Let the vessel cool to ambient temperature. Make up to the volume with water to 1 l. Stir to get a homogeneous solution. The pure citric acid content, ca, (C6H8O7), in grams per litre of this solution is calculated according
40、 to Formula (1) as follows. 17,45714,21014,192500=ca (1) where 500 is the added mass of mono hydrated citric acid (5.2), in grams; 192,14 is the molar mass of anhydrous citric acid, in grams; 210,14 is the molar mass of mono hydrated citric acid, in grams. 5.4 Calcium carbonate, precipitated (or PCC
41、), mass fraction, w(CaCO3) at least 99 %. Commercial PCC for analysis is granted for its chemical characteristics. However, physical characteristics are not granted. As reactivity depends on fineness, even for PCC, it is essential to take as a reference a highly reactive PCC, such as commercial PCC
42、from VWR / Prolabo / BDH, reference GPR, Rectapur, Ref 22296.294, Molar mass 100,09 1), which will consume 15 ml after 15 min. This PCC was used in the ring test before launching measurements. By experience, some PCC do not meet this requirement. See also the note in 7.2.6. 5.5 Silicone defoamer. 5.
43、6 Standard buffer solution, pH 4 (commercial solution, pH 4,01). NOTE This solution has a limited lifetime. 5.7 Standard buffer solution, pH 7 (commercial solution, pH 6,98). NOTE This solution has a limited lifetime. 6 Sampling and sample preparation 6.1 General Sampling is not part of the methods
44、specified in this document. A recommended sampling method is given in EN 1482-1. Sample preparation shall be carried out in accordance with EN 1482-2. 1) This substance is an example of a suitable product available commercially. This information is given for the convenience of users of this European
45、 Standard and does not constitute an endorsement by CEN of this product. BS EN 16357:2013EN 16357:2013 (E) 8 This document specifies that samples are tested “as received” in order to allow immediate starting of all the necessary measurements (NV, MgO). No preliminary determination is required to cal
46、culate tested sample mass. However, make sure that sample moisture is the same in the reactivity test portion as in the neutralising value measurement. Correcting factors are to be applied later on in the expression of results: actual citric acid concentration, exact mass of sample, as received neut
47、ralising value, MgO content. Such a procedure shortens the total necessary time for analysis because required measurements are made simultaneously, instead of successively. However, additional uncertainty introduced by the correction factors is not described in this document. Precision data mentione
48、d in Clause 9 do not take into account this additional uncertainty. All implemented correction factors should be evaluated to quantify the additional uncertainty they introduce to expression of the reactivity. NOTE This procedure is also better than drying the sample first and then titrate, because
49、drying can perhaps modify fineness or physical presentation and consequently reactivity of some products. 6.2 Preparation of the test sample Measure the moisture content of the tested material in accordance with EN 12048 and record the result for information. Make sure there is no oxide or hydroxide in the material to be tested (pH with 1/10 dilution shall be below pH 10). An oxide or hydroxide fraction in the product will bias the result. Oxide or hydroxide chemical forms are not included in the scope of this meth
