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Basic research on mineral flotation of Bayan Obo rare earth
Baotou Bayan Obo mine is a large deposits of iron, rare earths, niobium and other metals and fluorite symbiosis. Many kinds of mineral ores, disseminated complex relationships, a lot of minerals and small size relative to the physical and chemical properties, is widely recognized as difficult Xing dressing stone. After years of research, the Metallurgical Minister's Institute of Mining and Metallurgy has used the weak magnetic-strong magnetic-flotation process to transform the first and third series of Baotou Steel Concentrator, and achieved a major breakthrough in the ore dressing technology .
Experimental materials and experimental methods
Pure mineral and its preparation process
Select three main mineral ore from the tray main body Baiyunebo Ore - earth minerals (bastnaesite, monazite, and calcium fluorocarbon cerium ore), fluorite and martite two gangue minerals - calcite and Barite is the research object. At the same time, considering that the rare earth minerals in the deposit mainly occur in the form of close symbiosis of bastnasite and monazite, it is difficult to separate by mechanical means. In order to be closer to the actual situation, natural mixed rare earth minerals were used as artificial mixed minerals for research. In addition, in order to facilitate the study of the floating properties of minerals from the perspective of separation, in the experiments of flotation, adsorption and electrokinetic potential measurement, fluorite, imaginary hematite and calcite were all of the same grade -43 + 10 gm. This is because the particle size of the mixed rare earth mineral in the ore is very fine, about 70% less than 43mm. However, the measurement of the adhesion time of the ore particles to the bubbles was -0.15 + 0.074 mm.
The preparation of pure minerals varies slightly depending on the nature of the materials. The fluorocarbon ore, monazite and fluorocarbon calcium strontium ore are repeatedly selected by hand under the microscope, magnetically selected by hand magnets, and finally sieved to the desired size for use. After the mixed rare earth, imaginary hematite, fluorite, barite and calcite are crushed, 10 μm fine mud is removed by a classifier, re-elected, and the coarse concentrate is washed 7 times with distilled water, and dried at 60 ° C for magnetic separation. Finally, the concentrate screen is divided into various grades and stored in the ground glass bottle for storage. Strict attention was paid to the prevention of oil contamination during the treatment, and pure minerals were not chemically treated.
The chemical composition and mineral content of several pure minerals obtained by the above method are shown in Tables 1-1 and 1-2.
Table 1-1 Pure mineral chemical composition and mineral content
Mineral name
Size (mm)
content(%)
Mineral content (%)
Re x O y
F
Fe
Mixed rare earth mineral
-0.043+0.01
-0.015+0.074
-0.074+0.053
-0.053+0.043
71.68
71.72
70.88
70.75
4.33
4.21
1.71
2.56
Monazite 54
Bastosite 46
fluorite
-0.043+0.01
-0.21+0.01 each grade
trace
48.64
48.5-48.7
0.78
Fluorite 98-99
False hematite
-0.043+0.01
-0.21+0.01 each grade
0.19
0.21
69.32
69.2-69.4
False hematite 95
Hematite 4
Table 1-2 Pure mineral content
Mineral name
Size (mm)
Mineral content (%)
Remarks
Bastnasite
Monazite
Fluorocarbon calcium strontium ore
Calcite
Bastnasite
Monazite
Fluorocarbon calcium strontium ore
-0.2+0.05
-0.2+0.05
-0.2+0.05
95.4
2.6
1.1
96.3
0.5
0.3
99.1
2.7
0.3
X-ray diffraction data is very close to the literature standard
Flotation agent
Inorganic salt agents (all chemically pure or analytically pure); stearic acid, palmitic acid and lauric acid (both chemically pure, I made it); sodium oleate (BDH reagent);
Dextrin (made arbitrarily constant plant Germany); oxidized paraffin soap (Grease by Publisher, Shanghai China); oxidation of coal oil, sodium alkyl naphthalene sulfonate and acorn starch (I were prepared based insecticide); water glass ( The modulus is 1 and 2.7, containing SiO 2 27.96%, Na 2 O10.11%, water glass (modulus 1 and 2.7, containing SiO 2 27.96%, Na 2 O10.11%, Fe 2 O 3 0.58%) ).
Research methods:
Flotation - Flotation in L-type single-float flotation tubes and small thermostat flotation machines.
In addition to fluorocarbon antimony, monazite and fluorocarbon calcium strontium ore in flotation in L-shaped single bubble tube (mine sample weight 0.4g), mixed rare earth and other minerals in a volume of 20mL mechanical agitated constant temperature flotation machine During the flotation, the temperature of the slurry is maintained at 25±1°C, and the weight of each ore is 2g. The ratio of solid to liquid of the slurry is kept at 1:10 (for this reason, 20mL solution must be counted under the total volume of the agent under each condition), activator Or the inhibitor was added before the capture, and all the tests used distilled water. The flotation foam product and the unfloated parts in the tank were separately dried and weighed to calculate the recovery rate.
1. Determination of the amount of drug fixed on minerals - radioactivity measurement
Due to the high sensitivity of the radioisotope measurement method, the results are quite accurate. They are used to study the various regularities of the flotation process and expand our understanding of flotation theory.
We used the method of determining powder activity as developed by the Institute of Mining of the former Soviet Academy of Sciences.
The experimental steps are as follows:
(1) In order to effectively measure the β-rays radiated by 14C, a G-25-5Ф г bell-shaped counter tube having a mica window thickness of 1.8 mg/mm 2 was used. The working voltage of the counter tube was measured in the usual manner to determine the length of the ping.
(2) Standard curve drawing. For comparison, a solution of sodium laurate ( 14C ) at a known concentration was mixed with 1 g of mineral powder for 5 minutes, and then dried in an infrared drying oven. Dry the sample, measure the pulse number on the Б-2 type calibrator, and take the actual pulse number as the ordinate. The sodium laurate ( 14 C) content is plotted on the abscissa as the pulse number - sodium laurate ( 14 C ) Standard curve of content.
(3) Adsorption experiments. Take -43+10μm pure mineral weight 1g produced in glass, add 10mL of distilled water to make the mineral wet, add sodium laurate (14C) solution (saponification of lauric acid with AR sodium hydroxide), keep electromagnetic at constant temperature After stirring for 5 minutes on a stirrer, it is filtered on a special plexiglass funnel to obtain a mineral powder of a radioactive isotope-doping agent. After drying in infrared drying, it is placed in a small tray of plexiglass and flattened to maintain the same thickness of the ore layer. Then, the number of pulses per unit time is measured on a Б-2 type scaler, and converted into a dose of the drug adsorbed per ton of mineral according to a standard curve.
2. Determination of the electrical properties of mineral surfaces - Measurement of ξ-potentials by osmosis
The electroosmosis method recommended by Gorkykov was used to investigate the ξ-potential of the mineral surface. This method is simpler for the changes in the action of the modifier and is suitable for finer minerals. Its operation steps:
2g pure mineral with a particle size of -43+10μm was placed in the beaker, 20ml of distilled water was added, and the adjusting agent and the collecting agent were added in sequence (the same conditions as the flotation test). After stirring for 5 minutes, the ore particles were transferred into the U-shaped glass tube. by centrifuge 15min (3000r / min), and then the U-shaped tube loaded with salt bridge of the sample (saturated with two of KCl and agar glass, lower insertion beaker fitted with saturated copper sulfate solution. copper was placed The electrode is connected to the reading capillary (capacity 0.1mL), and the 270V DC power supply is turned on, and the volume and direction of the solution movement and the microampere reading are recorded within 5 minutes. After the measurement is completed, the solution is measured on a lightning magnetic 26 type conductivity meter, and finally the ξ-potential value is calculated by the following formula. [next]
2.5×10 6 ×ν×λ
ξ=-------------------------------
I
Where 2.5 × 10 6 - number;
Η—the flow velocity of the body (mL/min);
λ - specific electrical conductivity (Ω - 1 cm -1);
I - current intensity (mA).
3. Kinetics of minerals attached to bubbles - measurement of contact time
Greenbotski was improved on the basis of contactors from ÐЙreлec. This instrument was used in our research. Compared with the Aegles contactor, its greatest advantage is that the contact time between the mineral particles and the bubble is not controlled by the photographic shutter but by the electronic system. The part of the instrument that moves is a support bar with air bubbles, which is much lighter than a tank with minerals. The instrument consists of a capacitor that supplies time pulses and a motorized contact (wire pack) that is used exclusively for the instrument's contact part. It can measure up to 0.005s and the measurement accuracy is about 2-3%.
experimental method:
(1) t (time) - a (pointer deflection angle) drawing of the standard curve. The instrument uses an electronic millisecond meter to correct the true contact time of the contactor before use, and makes a ta standard curve of mineral adhesion to the bubble at three time intervals (5-50, 50-500, 500-5000 ms) for conversion during measurement;
(2) Same as other electronic instruments, turn on the 220V power supply, preheat for 15-20min;
(3) Put 1g of purely de-sludged and graded -100+200 mesh purity into a special glass and add distilled water (due to the hydrogen ion index of water, it has a great influence on the adhesion time of the ore particles on the bubble. In order to ensure the repeatability of the results, distilled water with fixed pH is used. Add the agent, stir on the electromagnetic stirrer, stir the adjusting agent and the collecting agent for 5 min, aspirate the solution with a syringe, wash once with distilled water, and then aspirate the solution. The mineral is washed into the quartz glass contact tank with a certain volume of distilled water, the mineral is flattened with the plexiglass plate, and the contact groove is vibrated. Finally, the mineral layer is flattened on the stage, and the special spiral feeder is supplied with a contact rod to specify the size of the bubble, and the micro-screw is twisted to bring the bubble and the ore layer close to the required distance to make the bubble and the ore. The deformation at the contact of the grain layer is constant. Control the bubble size and the distance between the bubble and the mineral layer by a multiple-magnitude horizontal microscope (with a gauge in its eyepiece) to be constant in each measurement, then circle the time index on the pulse generator to the desired measured time position . The given time pulse is achieved by the simplest pressing action, recording the exponential deflection angle. The contact time of the experiment can be found from the ta standard curve. The calculation of the attachment time can be calculated according to the method of the Institute of Mining Research of the former Soviet Academy of Sciences, that is, the measurement of the percentage of adhesion, or by the statistical method of the Aegis. The following measurements were taken and the readings were calculated in seconds: 0.005, 0.01, 0.02, 0.04, 0.1, 0.2, 0.5, 1, 3, 5, 10, 30, 60, 120, 300, 600. The attachment time of the ore particles is calculated as the arithmetic mean value;
∑p×t
T=-----------
∑p
Where T is the average attachment time of the ore particles;
T——time change, ie the attachment time of each particle;
p - the number of measurements 0 in this attachment time range.
The calculation is based on more than 20 measurements, and there are no less than two particles attached per time, and the average number of attached particles is from several to 100.