GB/T 37829-2019 in English

1. Standard Overview

GB/T 37829—2019 specifies the flow plate test method for the transportable moisture limit (TML) of bulk iron ore powder, which is applicable to iron ore powder with a nominal maximum particle size of $1\:\mathrm{mm}$. This standard was proposed by the China Iron and Steel Association and is under the jurisdiction of the National Technical Committee for Iron Ore and Direct Reduced Iron Standardization.

2. Experimental methods and steps

Experimental principle

The iron ore powder sample is made to flow through a vibrating flow plate instrument, and its moisture content is measured to determine the FMP and TML. The key steps include sample preparation, mold filling, tamping and vibration testing.

Instrument requirements

• Flow plate instrument: Contains matching molds and must meet the technical parameters of Appendix A.
• Tamper: An instrument used to apply uniform pressure.
• Balance: Maximum weighing $2\:\mathrm{kg}$, accuracy $0.1\:\mathrm{g}$.
• Drying plate: smooth surface, capacity adapted to sample volume.

3. Experimental steps analysis

Sample preparation

Sampling and sample preparation were carried out in accordance with GB/T10322.1 to ensure representativeness. The iron ore powder was fully stirred and divided into three parts: sample A for original moisture determination, pre-test sample B, and two parallel main test samples C and D.

Mold filling and tamping

Place the round mold in the center of the flow plate, fill the sample in three layers and tamp it. Calculate the tamping rod pressure $F=\rho\times h\times g\times s$, and the number of tamping times according to the layer: 35 times for the bottom layer, 25 times for the middle layer, and 20 times for the upper layer.

Vibration test

Start the flow plate instrument and vibrate the sample 50 times at a rate of 25 times/min. Observe whether the sample is broken or loose, and judge the relationship between water content and FMP. Determine the critical value of the flow state by gradually adjusting the amount of water added.

4. Data analysis and calculation

Flow moisture point (FMP) calculation

Formula: $$ \mathrm{FMP}=\frac{\displaystyle\frac{m_{1}-m_{2}}{m_{1}}+\frac{m_{3}-m_{4}}{m_{3}}}{2}\times100\% $$

• $m_1$: The mass just after reaching the flow state.
• $m_2$: The mass dried after the flow state.
• $m_3$: mass before flow.
• $m_4$: mass after drying before flow.

Calculation of Transportable Moisture Limit (TML)

Formula: $$ \mathrm{TML}=\overline{FMP}\times90\% $$

5. Precision and Implementation Suggestions

Precision Data

Repeatability limit $r=0.17\%$, reproducibility limit $R=0.62\%$, to ensure the reliability of the experimental results.

Implementation Suggestions

• Prepare samples and operate instruments in strict accordance with the standards to ensure data accuracy.
• It is recommended to conduct TML testing before actual transportation to assess the risk of cargo liquidity.
• Adjust experimental parameters based on different sample characteristics and optimize the detection process.