ISO 4280-1977 PDF

Full title and description

Cryolite, natural and artificial, and aluminium fluoride for industrial use — Determination of sulphate content — Barium sulphate gravimetric method. This International Standard specifies a gravimetric barium-sulphate procedure for determining sulphate (expressed as sulphur trioxide) in cryolite (natural and synthetic) and aluminium fluoride intended for industrial use.

Abstract

ISO 4280:1977 describes an analytical procedure based on alkaline fusion of a test portion with sodium carbonate and boric acid, extraction with perchloric acid, precipitation of sulphate as barium sulphate in an acidified medium, filtration on fine ashless paper, drying and calcination of the precipitate (approx. 850 °C) and weighing of the residue. The method is applicable to products with sulphate contents (as SO3) of 0.1 % (m/m) or greater.

General information

• Status: Published (International Standard; confirmed in systematic review cycles).
• Publication date: 1 November 1977 (1977-11-01).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 71.060.50 — Salts; materials related to production of primary aluminium.
• Edition / version: Edition 1 (1977).
• Number of pages: 3.

Key bibliographic details above are taken from the ISO bibliographic record and corroborated by national sales/registration entries.

Scope

This standard specifies a barium sulphate gravimetric method for the determination of the sulphate content of cryolite (natural and artificial) and aluminium fluoride intended for industrial use. It covers sample preparation by fusion and the subsequent chemical and gravimetric steps necessary to determine sulphate when the content (expressed as SO3) is ≥ 0.1 % (m/m). Normative references include ISO 1619 and ISO 2925 for sample preparation and storage.

Key topics and requirements

• Alkaline fusion of test portion with sodium carbonate and boric acid to convert sulphate into a soluble form.
• Acid extraction (perchloric acid solution) of the fused mass prior to precipitation.
• Precipitation of sulphate as barium sulphate in an acidified medium and use of fine-texture ashless filter paper (approx. 0.4–1.0 μm pore size) for collection.
• Drying and calcination of the barium sulphate precipitate (around 850 °C) followed by gravimetric weighing to determine sulphate content.
• Applicability threshold: intended for materials with sulphate (as SO3) ≥ 0.1 % (m/m).

Procedural steps and performance notes are defined concisely in the three-page specification.

Typical use and users

Laboratories and quality-control units in aluminium production, suppliers of cryolite and aluminium fluoride, chemical testing laboratories, and standards bodies use this method to verify sulphate impurities that can affect downstream aluminium electrolytic processes. It is intended for chemists and technicians experienced in gravimetric analysis and high-temperature calcination procedures.

Related standards

Normative and related documents commonly referenced with ISO 4280:1977 include ISO 1619 (Cryolite — Preparation and storage of test samples) and ISO 2925 (Aluminium fluoride — Preparation and storage of test samples). Other methods for related determinations (for example, XRF or atomic absorption methods for other analytes) are provided in neighbouring standards within the ICS 71.060.50 collection.

Keywords

cryolite; aluminium fluoride; sulphate determination; barium sulphate; gravimetric method; analytical chemistry; salts; aluminium industry.

FAQ

Q: What is this standard?

A: ISO 4280:1977 is an International Standard that specifies a barium-sulphate gravimetric method to determine the sulphate content of cryolite (natural and synthetic) and aluminium fluoride for industrial use.

Q: What does it cover?

A: It covers sample fusion and chemical treatment, precipitation of sulphate as barium sulphate, filtration, calcination and weighing steps required to quantify sulphate when present at or above 0.1 % (m/m).

Q: Who typically uses it?

A: Quality-control and analytical laboratories in the aluminium and chemicals industries, suppliers of cryolite and aluminium fluoride, and testing labs that perform gravimetric analyses.

Q: Is it current or superseded?

A: The ISO bibliographic record indicates ISO 4280:1977 was published on 1 November 1977 and has been subjected to periodic review; the ISO record shows it has been reviewed/confirmed in systematic reviews (confirmed in reviews up to and including 2020), and the published bibliographic entry remains listed as the 1977 edition. Users should check with national bodies or ISO for the very latest status before relying on the standard for regulatory or contractual purposes.

Q: Is it part of a series?

A: It is part of the group of ISO standards covering cryolite and related salts used in primary aluminium production; related documents addressing sample preparation and other determinations (e.g., ISO 1619, ISO 2925) are commonly associated.

Q: What are the key keywords?

A: Cryolite, aluminium fluoride, sulphate, barium sulphate, gravimetric, analytical method, salts, aluminium industry.