JPS62283820A - Method for obtaining iron oxide for producing ferrite from hematitic iron ore - Google Patents

Abstract

PURPOSE:To obtain high quality iron oxide for producing ferrite by combining the selection of magnetic separators with conditions during concentration under specified conditions so as to concentrate dry powdery hematitic iron ore by a dry process. CONSTITUTION:Hematitic iron ore 1 as raw material is divided into a part of >100 mesh, a part of 100 mesh-325 mesh, a part of 325 mesh-10mum and a part of <10mum with a sizing device 2. Since the parts of >100 mesh or of <10mum have a high impurity content, they are removed as matter 5 not to be concentrated. The medium grain size parts of 100 mesh-325 mesh and of 325 mesh-10mum, that is, parts each having <=5 ratio of the maximum grain size dmax to the minimum grain size dmin are fed to high gradient magnetic separators 3. Air is then fed to the separators 3 with exhaust fans at 2-8m/min flow rate so as to regulate the amount of the iron ore powder in each flow to 0.5-3kg/m<3>. Magnetized matter is taken out as iron oxide 4 for producing ferrite and unmagnetized matter is removed 5.

Description

[Detailed description of the invention] This invention is a magnetic separation method for separating and removing non-magnetic impurities mainly composed of silicon and aluminum compounds from dry powdered hematite iron ore to obtain high-quality iron oxide for producing ferrite. Regarding.

2. Description of the Related Art Methods for obtaining iron oxide for ferrite production from hematite iron ore include a wet magnetic beneficiation method and a flotation method. The wet method requires a step of drying the obtained iron oxide and returning it to powder, which requires a great deal of time and expense. On the other hand, as an example of a dry sorting method, there is a method in which impurities are removed by classification, but there are drawbacks such as low yield and insufficient removal of impurities.

Problems to be Solved by the Invention Hematite is paramagnetic and has a weak magnetic attraction, so in the dry magnetic sorting method, fine particles are not sufficiently captured as magnetized materials and flow out to the non-magnetic material side. Since non-magnetic impurities are mixed into the magnetized material and the impurities cannot be separated and removed sufficiently, the yield of the product obtained as a magnetized material is low, and the high Unable to obtain quality products. It has been difficult to obtain high-quality iron oxide for producing ferrite on an industrial scale by dry magnetically sorting this hematite iron ore.

Predetermined Means and Effects for Solving the Problems The inventor had conducted research on magnetically separating dry powdered hematite iron ore (hereinafter referred to as raw iron ore) in a dry process, but It has been found that a combination of selection and sorting conditions can yield high quality iron oxide for ferrite production.

This invention is based on this knowledge, which involves sizing raw iron ore to adjust the particle size within a certain range, using a high gradient magnetic separator, and adjusting the flow rate of the air passing through the magnetic separator and the airflow in the air flow. This is achieved by adjusting the content of raw material iron ore within a certain range and sorting it.

The following will be explained based on examples.

FIG. 1 is a system diagram showing one aspect of an embodiment of the present invention.

The raw material iron ore 1 is divided into parts coarser than 100 mesh, parts between 100 mesh and 325 mesh, and 3
The particles are divided into 25 mesh to 10 μm portions and 10 μm or less portions. Here, the particle sizer 2 is not particularly limited, but a sieve, a wind classifier, a cyclone classifier, etc. can be used alone or in combination. Both the part coarser than 100 mesh and the part 10 μm or less have a high content of impurities, making it difficult to improve the quality by sorting, and their quantity is also small, so they were excluded from the selection as removed material 5. In Fig. 1, the intermediate particle size part of 100 mesh to 10 μm is divided into two parts with 325 mesh as the boundary, but the upper limit particle size d max and the lower limit particle size d are the distribution range of the particle size supplied to magnetic separation. ==- ratio d
max/ds[i-4 or less is appropriate;
Even if it was large, it had to be 5 or less. Incidentally, the particle size as used in the present invention refers to the particle sizing point of a particle sizing device. The magnetic force that acts on magnetic particles in a magnetic separator is proportional to the cube of the particle diameter, so if the particle size distribution range is too wide, the difference in the magnetic force depending on the size of the magnetic particles becomes extremely large. It is difficult to provide appropriate screening conditions. On the other hand, if the range of particle size distribution is narrowed, the product in the intermediate particle size portion will be divided into many pieces, which increases the number of sorting steps, which is industrially disadvantageous. A high gradient magnetic force sorter 3 is used for magnetic sorting. The high-gradient magnetic force separator 3 sucks and introduces air using an exhaust fan (not shown), and uses the airflow to convey the sized raw material iron ore l to perform magnetic separation. The high gradient magnetic force separator 3 has a magnetic field strength of 3 to 5 kilogauss and an air flow velocity of 2 to 8 m.
/see was appropriate. If the flow rate is too high, the magnetic particles will be captured as magnetized particles by the magnetic separator 3 and carried away by the airflow toward the non-magnetized particles, resulting in poor yield. Since magnetic impurities are mixed into the magnetized material without being sufficiently separated, the quality of the iron oxide for producing ferrite obtained as the magnetized material is deteriorated.

Moreover, the content of the raw material iron ore 1 provided in this air stream is 0.
A suitable ratio is 5 to 3 Kq/-. If the content is too low, the sorting performance will deteriorate and the processing efficiency will be lowered, and if the content is too large, the quality of the magnetized material will be inadequate, making it difficult to supply the raw material iron ore 1, or causing high gradient magnetic separation. Since problems such as internal clogging of the machine 3 occur, a product satisfying the quality as iron oxide 4 for producing ferrite was obtained within the above content range.

Non-magnetic impurities that are not captured as magnetized substances flow out of the high gradient magnetic force separator 3 as non-magnetized substances along with the air current, and become removed substances 5.

The magnetic substances captured in the high gradient magnetic force separator 3 as magnetized substances are removed by stopping the supply of the raw iron ore 1 and erasing the magnetic field of the high gradient magnetic force separator 3, and then carried out by airflow to become the removed material 5. is recovered separately and becomes iron oxide 4 for ferrite production.

Example 7 Based on the system of the first example, Brazilian iron ore pellet feed (5 in. 20.65 in., 30.56 in.) was treated to obtain the results shown in Table 1.

The equipment and operating conditions used at this time were as follows.

The particle sizer 2 uses a dry cyclone with a diameter of 300 mm with a classification point of 10 μm, and uses 100 mesh and 325 mesh sieves. The high gradient magnetic force separator 3 was a cyclic type model 10-15-20 manufactured by Jyuu Co., Ltd. and used with a magnetic field strength of 5 kilogauss.

Effects of the Invention According to the present invention, dry powdered hematite iron ore can be dry-sorted to obtain high-quality iron oxide for producing ferrite, which has great industrial value.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing one aspect of an embodiment of the present invention. 1...Raw material iron ore 2...Sizing device 3...
High gradient magnetic force separator 4...Iron oxide for ferrite production 5...Removed material

Claims (1)

[Claims] In a magnetic separation method for obtaining iron oxide for ferrite production from dry powdery hematite iron ore using a magnetic separation machine, the upper limit particle size dmax and the lower limit particle size dmi of the particle size distribution range are used.
Hematite iron ore that has been sized so that the ratio dmax/dmin of n is 5 or less is supplied to a high gradient magnetic force separator into which air is introduced by an exhaust fan, and the air passes through the high gradient magnetic force separator. Air flow velocity 2m/sec or more 8m/sec
Hematitic iron ore, which is adjusted to the following and magnetically sorted so that the content of hematitic iron ore in the air flow is 0.5 Kg/m^3 or more and 3 Kg/m^3 or less. How to obtain iron oxide for ferrite production from.