ISO 7990:1985

Name: ISO 7990:1985 — Manganese ores and concentrates — Determination of total iron content — Titrimetric method after reduction and sulfosalicylic acid spectrophotometric method
SKU: ISO 7990:1985
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Manganese ores and concentrates — Determination of total iron content — Titrimetric method after reduction and sulfosalicylic acid spectrophotometric method

Название (английский):

ISO 7990:1985

Manganese ores and concentrates — Determination of total iron content — Titrimetric method after reduction and sulfosalicylic acid spectrophotometric method

Статус документа:: Действующий
Формат:: Электронный (PDF)
Количество страниц:: 6
Дата публикации:: 12 декабря 1985 г.
Издание:: ISO IS 7990 edition 1 version 1
ICS:: 73.060.20

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Описание (английский):

Method A is applicable to products having a total iron content from 1 to 25 % (m/m), and method B is applicable to products having a total iron content from 0.2 to 2 % (m/m). ISO 7990 should be read in conjunction with ISO 4297. Specifies principle, reactions (method A only), reagents, apparatus, sampling and samples, procedure and expression of results.

Abstract

Похожие стандарты

Стандарты, упомянутые в описании

Overview

ISO 7990:1985 specifies two validated laboratory procedures for the determination of total iron in manganese ores and concentrates. The document defines: Method A (titrimetric after reduction) for samples with total iron from 1 to 25 % (m/m), and Method B (sulfosalicylic acid spectrophotometric) for samples with total iron from 0.2 to 2 % (m/m). The standard is intended to be read in conjunction with ISO 4297 and the ISO 4296 series for sampling and sample preparation.

Both methods cover principle, reagents, apparatus, sampling/sample preparation references, analytical procedure and expression of results, and provide tolerances for parallel determinations so laboratories can assess precision and repeatability.

Key Topics

Principles

Method A: reduction of Fe(III) to Fe(II) (tin(II) reduction), oxidation of excess reductant, and titration of Fe(II) with potassium bichromate using diphenylamine sulfonate as indicator.
Method B: formation of a coloured complex between iron and sulfosalicylic acid in alkaline medium; interference from manganese is removed by hydroxylammonium chloride and absorbance is measured near 430 nm.

Scope and applicability

Method A: suitable for ores/concentrates containing 1–25 % total iron (m/m).
Method B: suitable for lower-iron products, 0.2–2 % total iron (m/m).

Sample handling & preparation

Uses ISO 4296/1 and ISO 4296/2 for sampling and sample preparation guidance; includes instructions for dissolution methods for easily and poorly soluble materials and for treatment of residues (fusion, acid attack).
Typical sample residue incineration and fusion steps (as given in the standard) are included to ensure complete recovery of iron.

Reagents & apparatus

Method A lists reductants (tin chloride), oxidants (mercury chloride, permanganate) and titrated bichromate solutions and indicator.
Method B lists sulfosalicylic acid, hydroxylammonium chloride and spectrophotometric measurement equipment.

Applications

ISO 7990:1985 is practical for:

Quality control and specification testing of manganese ores and concentrates.

Acceptance testing during trade and processing when accurate total iron content is required.

Analytical laboratories performing routine compositional assays and inter-laboratory comparisons.

Advantages include clearly defined concentration windows for each method, stepwise sample treatment for difficult matrices, and prescribed expression of results with tolerances for parallel assays.

Related Standards

ISO 4296-1 - Sampling of manganese ores (field sampling)

ISO 4296-2 - Preparation of samples for analysis

ISO 4297 - Manganese ores and concentrates - General instructions for chemical analysis

For implementation, laboratories should follow the reagent, apparatus and procedural details specified in ISO 7990:1985 and cross-reference ISO 4296/ISO 4297 for sampling and sample preparation to ensure representative and reproducible results.

ISO 7990:1985

Abstract

Похожие стандарты

Overview

Key Topics

Applications

Related Standards

Технические детали

ISO 4297:1978

Manganese ores and concentrates — Methods of chemical analysis — General instructions

ISO 4296-1:1984

Manganese ores — Sampling — Part 1: Increment sampling

ISO 4296-2:1983

Manganese ores — Sampling — Part 2: Preparation of samples