GB/T 29516-2013Manganese ores -- Determination of moisture content (English PDF)

8.1 Calculation of moisture content of test portion

The moisture content wi is calculated according to formula (1), expressed in mass fraction (%). The result is expressed to two digits after the decimal place:

Where, m1 - Initial mass of test portion, in grams (g);

m2 - Dried mass of test portion, in grams (g).

8.2 Calculation of moisture content of consignment

8.2.1 When moisture is determined by gross sample, the moisture content of consignment shall be calculated according to formula (2). The result is expressed to one digit after the decimal place:

Annex A (normative)

Test method for moisture content of sticky manganese

When the sample is difficult to sieve, break or divide due to excessive humidity or stickiness, it may perform pre-drying. In such a situation, it shall conduct the moisture test according to the following pre-drying methods.

A.1 Weigh the initial mass of the test sample.

A.2 Tile the test sample to the uniform thickness. Place it in the air or place it in a drying oven of which the temperature is not greater than 105°C. The drying temperature and time shall not cause the sample to reabsorb moisture in the subsequent operations.

A.3 Weigh the dried manganese ore once again.

A.4 According to formula (A.1), calculate the pre-drying moisture content of the

test sample wp (%):

Where,

- Test sample mass before pre-drying, in kilograms (kg);

- Test sample mass after pre-drying, in kilograms (kg).

A.5 Record the pre-drying moisture content to the second digit after the decimal

place.

A.6 Prepare test portion from the pre-drying samples according to Clause 6.

A.7 Measure the weight loss of test portion. According to the method described

in Clause 7, then according to sub-clause 8.1, calculate the moisture content of test portion (mass fraction).

A.8 According to formula (A.2), calculate the total moisture content, wpd (%):

Annex B (normative)

Calibration of sprayed water and/or rain

B.1 Introduction

To prevent dust from polluting the environment, it needs to spray water on the ores during loading-unloading. Therefore, the moisture content of the consignment shall be calibrated according to the mass of sprayed water. The calibration procedures are in accordance with the provisions of this Annex.

This Annex is also applicable to the moisture content calibration of the consignment of manganese ores that are exposed in rain.

B.2 General rules

B.2.1 Sprayed water due to the following reasons:

a) The environmental regulations of loading/unloading ports have requirements for dust;

b) It is more convenient to spray water for reasons such as minerals, weather, or disposal equipment.

B.2.2 When the rain has a considerable effect on the moisture content of the consignment, it shall consider the rain calibration. But the corrected coefficient shall be agreed with the relevant stakeholders.

B.3 Calibration of sprayed water

B.3.1 Sprayed water

Sprayed water refers to the water that is added between the moisture determination and the determination of total mass of cargo.

B.3.2 Determination of sprayed water mass

It may use a flowmeter of which the accuracy is ±5% to determine the sprayed water mass. Multiply the determined volume by the density of the sprayed water and convert it to the mass m3 that is represented in t.

NOTE: The density of fresh water is assumed to be 1t/m3.

B.3.3 Mass of consignment

B.4.2 Effective area exposed to rain

The effective area exposed to rain shall be calculated according to the provisions of B.4.2.1~B.4.2.3 and rounded off to square meters.

B.4.2.1 Cargo compartment

The area calculation of cargo compartment exposed to rain shall be based on the cargo ship plan view provided by the ship owner.

B.4.2.2 Feed bin

The area calculation of feed bin exposed to rain shall be based on the feed bin plan view.

B.4.2.3 Belt transport

During belt transport, the calculation of the area exposed to rain shall multiply the effective width of the belt by the length of the exposed rain, that is, the distance from the container to the sampling point when the cargos are transported.

B.4.3 Rainfall duration

If the vessel uses a water gauge to weigh, the rainfall duration shall be from the beginning of the water gauge identification to the end of sampling.

B.4.4 Measurement method of rainwater

The measurement of rainwater shall use a certified rain gauge. During measurement, place it near the loading-unloading ores. The rainfall is expressed in millimeters (mm).

B.4.5 Mass of rain

The mass of rain is expressed in mR, in tons (t). Use formula (B.3) to calculate to an integer.

Where,

A - Raining effective area calculated according to B.4.2, in square meters (m2);

R - Rainfall measured according to B.4.4, in millimeters (mm);

rho - Rain density, in tons per cubic meter (t/m3); usually it is 1t/m3.

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