Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D5341 – Standard Test Method Technical Guide
📐 Overview and Scope of ASTM D5341/D5341M‑19
ASTM D5341/D5341M‑19, officially titled “Standard Test Method for Measuring Coke Reactivity Index (CRI) and Coke Strength After Reaction (CSR),” is a critical standard under the jurisdiction of ASTM Committee D05 on Coal and Coke. It is the direct responsibility of Subcommittee D05.15 on Metallurgical Properties of Coal and Coke. Originally approved in 1993, the standard was last revised in 2019 and is issued under the fixed designation D5341/D5341M.
The primary scope of this standard is to describe the equipment and techniques used for determining lump coke reactivity in carbon dioxide (CO₂) gas at elevated temperatures. It also defines the method to measure the strength of the coke after it has undergone this reaction. This is achieved by tumbling the reacted coke in a cylindrical chamber known as an I‑tester. This standard is patterned specifically after the Nippon Steel test procedure detailed in Carbonization Research Report 91.
⚠️ Unit Compliance Warning: The values stated in either SI units or inch‑pound units are to be regarded separately as standard. They are not exact equivalents. To ensure conformance with the standard, each system must be used independently, and values from the two systems shall not be combined.
⚙️ Test Method and Reagent Specifications
The test method involves reacting a sample of dried coke of a designated origin and size with CO₂ gas in a retort at a specified elevated temperature for a specified length of time. This strictly controlled procedure is designed to simulate the concurrent chemical and physical stresses that coke lumps endure in a blast furnace environment.
The gases used in this method are critical to its accuracy. High‑purity nitrogen is required to act as an inert sweep gas before and after the reaction. Carbon dioxide is used as the primary reactive gas.
| 🟦 Reagent | 📏 Purity Requirement | 🎯 Impurity Limit |
|---|---|---|
| Nitrogen | ≥ 99.9 % by volume | Total O₂ + CO₂ < 100 mg/kg |
| Carbon Dioxide | High purity (by specification) | Used as reactive gas |
💡 Method Utility: “When coke lumps descend in the blast furnace, they are subjected to reaction with countercurrent CO₂ and to abrasion … This test method is designed to measure indirectly this behavior of coke in the blast furnace.” — ASTM D5341, Section 4.1
📊 Key Measured Properties: CRI and CSR
Two primary indices are generated from the reacted coke residue. The first is the Coke Reactivity Index (CRI), which is determined directly from the mass or weight loss of the sample after its reaction with CO₂. The second is the Coke Strength After Reaction (CSR), which is determined from the mass or weight retained after sieving the tumbled reacted coke in a designated number of revolutions over a designated turning rate in the I‑tester.
| 📐 Index | 🎯 Definition | ⚡ Industrial Significance |
|---|---|---|
| CRI | % Weight loss after CO₂ reaction | Indicates the reactivity of the coke to gasification |
| CSR | % Weight retained after tumbling and sieving | Measures the mechanical strength of the coke after chemical degradation |
An excess of fines due to poor CSR can decrease burden permeability in the blast furnace, resulting in increased coke rates and lost hot metal production. Therefore, these two measurements are vital for metallurgical coke evaluation and quality control.
❓ Frequently Asked Questions
🔍 What is the official designation and date of this test method?
The official designation is D5341/D5341M‑19. It was originally approved in 1993 and the last previous edition was D5341/D5341M – 18 before the current 2019 edition.
💡 What are the key purity requirements for Nitrogen used in this test?
According to Section 5.1, the Nitrogen must have a purity greater than 99.9 % by volume, be dry, and have total oxygen and carbon dioxide concentrations of less than 100 mg/kg.
⚡ How does the test method define the Coke Strength After Reaction (CSR)?
The CSR is defined as the mass or weight retained after sieving the tumbled reacted coke. The tumbling occurs in an I‑tester for a designated number of revolutions at a specific turning rate.
📌 What is the significance of the CRI and CSR values for blast furnace operations?
These values measure how coke behaves under reaction with CO₂ and subsequent abrasion. This helps predict the generation of fines in the blast furnace, which directly