1、PUBLISHED DOCUMENTPD CEN/TR 15018:2005Characterization of waste Digestion of waste samples using alkali-fusion techniquesICS 13.030.01g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g
2、50g51g60g53g44g42g43g55g3g47g36g58PD CEN/TR 15018:2005This Published Document was published under the authority of the Standards Policy and Strategy Committee on 19 January 2006 BSI 19 January 2006ISBN 0 580 47029 6National forewordThis Published Document is the official English language version of
3、CEN/TR 15018:2005.The UK participation in its preparation was entrusted by Technical Committee B/508, Waste management, to Subcommittee B/508/3, Waste characterization, which has the responsibility to: A list of organizations represented on this subcommittee can be obtained on request to its secreta
4、ry.Cross-referencesThe British Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of Britis
5、h Standards Online.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a Published Document does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present
6、to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK.Summary of pagesThis document comprises a front cover, an inside fro
7、nt cover, the CEN/TR title page, pages 2 to 25 and a back cover.The BSI copyright notice displayed in this document indicates when the document was last issued.Amendments issued since publicationAmd. No. Date CommentsTECHNICAL REPORTRAPPORT TECHNIQUETECHNISCHER BERICHTCEN/TR 15018November 2005ICS 13
8、.030.01English VersionCharacterization of waste - Digestion of waste samples usingalkali-fusion techniquesCaractrisation des dchets - Digetsion dchnatillon dedchets par Mise en solution par fusion alcaline - Guide debonnes pratiques pour la mise en solution par fusion - Lesdiffrentes mthodes et prot
9、ocoles existantsAufschluss von Abfallproben mittels AlkalifusionThis Technical Report was approved by CEN on 6 December 2004. It has been drawn up by the Technical Committee CEN/TC 292.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finlan
10、d, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUN
11、GManagement Centre: rue de Stassart, 36 B-1050 Brussels 2005 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. CEN/TR 15018:2005: E2 Contents Introduction4 1 Scope .5 2 General information5 2.1 Digestion of samples 5 2.2 Digestion by fusi
12、on.5 3 Fluxes 6 3.1 Alkaline fluxes.7 3.2 Acid fluxes.10 3.3 Oxidising fluxes 11 3.4 Reducing fluxes (alkaline fluxes + reducing agents, sulphides).12 3.5 Digestion by sintering 12 4 The crucibles.12 4.1 Platinum.12 4.2 Silver 13 4.3 Nickel .13 4.4 Vitreous carbon.13 4.5 Iron.13 4.6 Porcelain13 5 Pr
13、otocols currently used within industry13 5.1 Analysis of 16 metallic elements in crushing residues 11 13 5.2 Determination of Si, Al, Fe, Mn, Mg, Cr, Ti, and F in slags 12 .15 5.3 Fusion with carbonate or borate mixture 15.16 5.4 Fusion with lithium borate 14 17 5.5 Standards (non exhaustive list) .
14、17 5.6 Fluxes and their applications.18 6 Comparison of different digestion techniques .21 7 Conclusion 23 Bibliography.24 CEN/TR 15018:20053 Foreword This Technical Report (CEN/TR 15018:2005) has been prepared by Technical Committee CEN/TC 292 “Characterization of waste”, the secretariat of which i
15、s held by NEN. This Technical Report is the translation of the French guideline BP X 30-428 “Digestion by fusion Good practice guide for digestion by fusion: the different existing methods and protocols“ and adoption as a CEN/TR. It gives information about the digestion of the waste samples using al
16、kali-fusion techniques. CEN/TR 15018:20054 Introduction EU regulations (e.g. hazardous waste, waste incineration, European waste catalogue) ask in many cases for the total content of certain elements. In the European landfill directive, knowledge of total composition is given as an example of waste
17、property-based criteria and is part of the basic characterization of waste. In these special cases the total content of certain elements has to be determined. The standard based on acid digestion of waste samples (EN 13656) is in almost all cases applicable. However for some elements or waste compos
18、ed of very refractory matrix (e.g. silicates, carbides, oxides), or when some residue is left after acid digestion, alkali-fusion may be used to bring the waste sample completely into solution. CEN/TR 15018:20055 1 Scope This Technical Report describes digestion methods for the determination of elem
19、ent contents of waste samples by using different alkali-fusion techniques. 2 General information 2.1 Digestion of samples The determination of the elemental chemical composition of waste material includes a pretreatment of the sample comprising several stages: sampling for analysis (drying, crushing
20、, homogenisation, sample reduction); digestion. This last stage of digestion is essential because it allows to obtain a homogenous medium compatible with current analytical methods (atomic absorption spectrometry AAS, inductively coupled plasma and atomic emission spectrometry ICP/AES, inductively c
21、oupled plasma mass spectrometry ICP/MS, molecular absorption spectrometry MAS, X-ray fluorescencespectometry XRF). The diversity of the materials is such that this stage remains very complex and can give rise to major errors due mainly to: contamination of the sample by digestion reagents; incomplet
22、e digestion; loss of elements by adsorption onto the mineralization residue, onto the filter, or onto the walls of the mineralization reaction vessel; loss of elements by volatilisation (over and above those connected with drying and crushing); loss by reprecipitation in the form of hardly soluble s
23、alts. Digestion is generally conducted in two stages. The attack, which consists in destroying the samples organic matter and in dissolving the mineral residue by possibly modifying the specification by a very aggressive medium, followed by a dilution of the residue by a liquid allowing to obtain a
24、homogeneous solution compatible with the subsequently implemented analytical techniques. Specific methods have been developed for volatile elements. While numerous digestion methods exist, none is universal. The choice depends, on the one hand, on the nature of the sample (matrix type) and, on the o
25、ther hand, on the sought after element(s) or on the targeted objective : determination of the total content or search for exogenous contaminants. Digestion can be performed by a wet (acid attack) or dry (fusion, calcination, combustion) technique. The purpose of this code of good practices is to inv
26、entory those fusion methods which allow the mineralisation and digestion of waste for which acid attacks do not give satisfactory results. 2.2 Digestion by fusion Fusion is often employed for the digestion of mineral materials (silicates, alumino-silicates, .) and more particularly of certain refrac
27、tory oxides (zircon, chromite, .), but it is unsuitable for the digestion of volatile elements. CEN/TR 15018:20056 Digestion by fusion requires the use of a specific flux which determines the nature of the reaction involved: acid-alkaline reaction: alkaline fusion (carbonates, borates, hydroxides);
28、acid fusion (disulphates and pyrosulphates, fluorides, boron oxides); redox reaction: oxidizing fusion (alkaline fluxes + oxidants, peroxides); reducing fusion (alkaline fluxes + reducing agents, sulphides). Fusion is conducted in platinum, porcelain, silver, nickel, iron, vitreous carbon, zirconium
29、, graphite or terracotta crucibles. The choice of the crucible depends on the nature of the substance to be decomposed and on the type of flux. Heating can take place in muffle ovens, induction ovens, tunnel ovens, over flames (Mecker burner) or more recently in microwave ovens. The time and tempera
30、ture vary depending on the sample, crucible and flux being used. The dilution of the fusion product is generally carried out in water or acidified water (water acidified with hydrochloric or nitric acid up to 5 % ml/l) which is heated in order to solubilise the solid formed at time of fusion. 3 Flux
31、es Several types of salts or other chemicals are proposed for the fusion of rock samples: alkaline borates, sodium carbonate (Na2CO3), sodium hydroxide (NaOH), sodium peroxide (Na2O2), equivalent potassium compounds, potassium pyrosulphate (mixture of K2S2O7and KHSO4), alkaline fluorides (e.g. : KHF
32、2). These fluxes have specific applications. In general, the efficiency of a flux for attacking silicate rocks increases from Na2CO3 NaOH Na2O2. Table 1 gives a non exhaustive list of the fluxes together with their melting point and the generally used crucibles. CEN/TR 15018:20057 Table 1 Fluxes use
33、d for the fusion of silicate rocks Salt Melting point (C) Fusion crucible Lithium metaborate LiBO2845 Pt + 5 % Au Lithium tetraborate Li2B4O7930 or graphiteSodium carbonate Na2CO3851 Pt or Ni Potassium carbonate K2CO3891 Sodium hydroxide NaOH 318, 314aZr (or Au, Ni, Ag) Potassium hydroxide KOH 360 S
34、odium tetraborate (borax) Na2B4O7741 Sodium peroxide Na2O2480 d, 675aZr Potassium superoxide KO2380 Potassium fluoride KF 846, 856aPotassium hydrogen fluoride KHF2225 d, 239aPotassium pyrosulphate K2S2O7300, 414aSodium pyrosulphate Na2S2O7401aLithium carbonate LiCO3720aCesium carbonate CsCO3610aSodi
35、um Potassium carbonate NaKCO3500aAmmonium hydrogen sulphate NH4HSO4147aSodium hydrogen sulphate NaHSO4185aPotassium hydrogen sulphate KHSO4214aAmmonium hydrogen fluoride NH4HF2125aSodium nitrate NaNO3306aPotassium nitrate KNO3339aad : decomposes. 3.1 Alkaline fluxes 3.1.1 Carbonates Fusion using sod
36、ium carbonate is the most generally employed method of attack for the digestion of silicates (rocks and glasses). One can use either sodium carbonate which melts at 850 C, or a mixture of potassium carbonate and sodium carbonate in equal parts, an eutectic mixture which melts at 700 C. Sodium and po
37、tassium carbonate (NaKCO3) has a melting point of 500 C. Potassium carbonate is rarely used alone. Mixed with sodium carbonate, it is used for analysing silicates because the fusion temperature is lower than that of the sodium carbonate alone. This mixture can therefore be used for the determination
38、 of volatile elements such as chlorine, fluorine. Sometimes a little nitrate is added in order to stimulate the oxidation of chromium for example. Fusions using carbonates generally take place in platinum crucibles at 900 C. These fusions shall be performed preferably in an inert atmosphere in order
39、 to limit the formation of soluble sodium platinate. CEN/TR 15018:20058 Conversely, when the sample under analysis contains iron, the fusion shall be conducted maintaining an oxidising atmosphere inside the crucible in order to prevent the reduction of the iron and the attack of the platinum crucibl
40、e. During fusion using carbonates, Hg and Tl volatilise completely, As and Se partially. After attack, the majority of the anions are dissolved in the water; metals which do not produce any anions remain in the state of oxides, but these oxides are generally able to be attacked by acids. Fe (III), T
41、i (IV), Zr (IV), Be (II), rare earths remain insoluble in the water in the state of oxides. Al (III), V (V), P (V) are dissolved in the state of anions, as well as chromium in the state CrO42- after oxidation by the air during fusion. U divides into parts; likewise for Zn which is in the state of Zn
42、O2 2- and of ZnCO3. Mn2+ changes partially to the state of MnO42- ; post-dilution boiling or the addition of a drop of alcohol produces MnO2which precipitates. In presence of SiO2and Al2O3, sodium silicoaluminates form that are hardly soluble and very difficult to filter when diluted by the water. W
43、here anion separation is not required, it is preferable to directly dilute the attack product by an acid, and to insolubilise the silicium oxide 3 and 8. Procedure : 0,8 g to 1 g of finely crushed1)sample is mixed in a platinum crucible with 4 g to 5 g of the equal parts mixture of anhydrous sodium
44、and potassium carbonates. First of all heat gently for 5 min, then to fusion for 30 min. When there is no longer formation of CO2bubbles, heat as high as possible during 10 min. Allow to cool, solidifying the content in a film on the walls of crucible. Fill up to a third with water; heat gently. Rem
45、ove the solid. If unable to do so, place the crucible in a beaker in presence of water. Heat up until disintegration 3. Fusion with sodium carbonate mixed with SiO2has been used for the determination of the fluorine and chlorine present in geological materials 10. Fusion takes place in a platinum cr
46、ucible at 900 C for 30 min. It shall also be noted that alkaline carbonates can be used mixed with: a compound of boron for the analysis of highly refractory products (natural oxides or calcined aluminium or silicium, corundums, zircons, cassiterites, chromites, .); a MgO or ZnO oxide in order to in
47、crease the fusion temperature (use of a porcelain crucible); sulphur for the analysis of tin oxide and materials forming soluble sulphurs compounds in an alkaline medium; an oxidant (alkaline peroxide or nitrate) for the determination of the chromium and sulphur in silicates and chromites containing
48、 lead; ammonium chloride. 3.1.2 Molten borates Lithium metaborate and tetraborate These are widely used fluxes. Metaborate is more alkaline than tetraborate. It is used for dissolving acid materials: silicate materials, siliceous sands, acid oxides 13. Lithium metaborate is used preferably in view o
49、f analyses by AAS or ICP after dilution. Tetraborate, more acidic, is used for the attack of alkaline materials such as alkaline oxides, highly aluminic materials, alumino-silicates, bauxites.13. 1) Gradings not exceeding 200 m - 300 m are recommended. CEN/TR 15018:20059 The metaborate/tetraborate mixture in a 4/1 ratio constitutes a practically universal flux. The eutectic point of this mixture is one of the lowest; it is efficient in 95 % of cases, just as much for the fusion of siliceous rocks as for alu
