1.4 Modified Proctor/Fagerberg test procedure for Iron Ore Fines

1.4.1 Scope

• .1 The test procedure specified in this section (this test) should only be used for determining transportable moisture limit (TML) of iron ore fines. See individual schedule for iron ore fines.

• .2 iron ore fines is iron ore containing both:

  • .1 10% or more of fine particles less than 1 mm; and

  • .2 50% or more of particles less than 10 mm.

  • .3 The TML of iron ore fines is taken as equal to the critical moisture content at 80% degree of saturation according to the modified Proctor/Fagerberg method test.

  • .4 The test procedure is applicable when the degree of saturation corresponding to optimum moisture content (OMC) is 90% or higher.

1.4.2 Modified Proctor/Fagerberg test equipment

• .1 The Proctor apparatus (see figure 1.4.1) consists of a cylindrical iron mould with a removable extension piece (the compaction cylinder) and a compaction tool guided by a pipe open at its lower end (the compaction hammer).

• .2 Scales and weights (see 3.2) and suitable sample containers.

• .3 A drying oven with a controlled temperature interval from 100°C to maximum 105°C.

• .4 A container for hand mixing. Care should be taken to ensure that the mixing process does not reduce the particle size by breakage or increase the particle size by agglomeration or consistency of the test material.

• .5 A gas or water pycnometry equipment to determine the density of the solid material as per a recognized standard (e.g. ASTM D5550, AS1289, etc.)

1.4.3 Temperature and humidity

(see 1.1.3)

1.4.4 Procedure

• .1 Establishment of a complete compaction curve

  • A representative sample according to a relevant standard (see 4.7 of this Code) of the test material is partially dried at a temperature of approximately 60°C or less to reduce the sample's moisture to suitable starting moisture, if needed. The representative sample for this test should not be fully dried, except in case of moisture content measurement.

  • The total quantity of the test material should be at least three times as big as required for the complete test sequence. Compaction tests are executed for five to ten different moisture contents (5 to 10 separate tests). The samples are adjusted in order that partially dry to almost saturated samples are obtained. The required quantity per compaction test is about 2,000 cm³.

  • At each compaction test a suitable amount of water is added to the sample of the test material. The sample material is gently mixed before being allowed to rest and equilibrate. Approximately one fifth of the mixed sample is filled into the mould and levelled and then the increment is tamped uniformly over the surface of the increment. Tamping is executed by dropping a 150 g hammer 25 times through the guide pipe, 0.15 m each time. The performance is repeated for all five layers. When the last layer has been tamped, the extension piece is removed and the sample is levelled off along the brim of the mould with care, ensuring to remove any large particles that may hinder levelling of the sample, replacing them with material contained in the extension piece and re-levelling.

  • When the weight of the cylinder with the tamped sample has been determined, the cylinder is emptied, the sample is dried at 105ºC and the weight is determined. Reference is made to ISO 3087:2011 "Iron ores – Determination of the moisture content of a lot". The test then is repeated for the other samples with different moisture contents.

  • Density of solid material should be measured using a gas or water pycnometry equipment according to internationally or nationally accepted standard, e.g. ASTM D5550 and AS 1289 (see 1.4.2.5).

• .2 Definitions and data for calculations (see figure 1.4.2)

  • - empty cylinder, mass in grams: A

  • - cylinder with tamped sample, mass in grams: B

  • - wet sample, mass in grams: C

  • C = B - A

  • - dry sample, mass in grams: D

  • - water, mass in grams (equivalent to volume in cm³): E

  • E = C - D
  • Volume of cylinder: 1,000 cm³
  • 

• .3 Calculation of main characteristics

  • - density of solid material, g/cm³ (t/m³): d

  • - dry bulk density, g/cm³ (t/m³):

  • 

  • - net water content, volume %: e_v

  • 

  • - void ratio: e (volume of voids divided by volume of solids)

  • 

  • - degree of saturation, percentage by volume: S

  • 

  • - gross water content, percentage by mass: W¹

  • 

  • - net water content, percentage by mass: W

  • 

• .4 Presentation of the compaction tests

  • For each compaction test the calculated void ratio (e) value is plotted as the ordinate in a diagram with net water content (e_v) and degree of saturation (S) as the respective abscissa parameters.

• .5 Compaction curve

  • The test sequence results in a specific compaction curve (see figure 1.4.3).

  • The critical moisture content is indicated by the intersection of the compaction curve and the line S = 80% degree of saturation. The transportable moisture limit (TML) is the critical moisture content.

  • Optimum moisture content (OMC) is the moisture content corresponding to the maximum compaction (maximum dry density) under the specified compaction condition. To check the applicability of this test, the relationship between moisture content and dry density should be evaluated, during this test. Then the OMC and the corresponding degree of saturation should be determined. This test procedure was developed based on the finding that the degree of saturation corresponding to OMC of iron ore fines was 90 to 95%, while such degree of saturation of mineral concentrates was 70% to 75%. In the case that the degree of saturation corresponding to OMC is less than 90%, the shipper should consult with an appropriate authority, for the reason that this test may not be applicable for the material and the TML determined by this test may be too high.