Patent Application
20110027158
This invention; relates to production of micronized calcined tincal having a high content as a result of a succession of procedures consisting of: hardening of earth minerals due to lose of water during subjecting coarse tincal ore (Na2B4O7.10H2O) to heat treatment in rotary furnace with flights; forming of swollen soft, expanded structure of tincal ore caused by calcination and consequently being calcined followed by purification from impurities in a high rate in a way subjecting calcined tincal to pneumatic separation procedure by means of hot air used for calcination process after autogenic grinding effect of dried and hardened clays on swollen ore and obtaining micronized calcined tincal with high efficiency. The invention also relates to the production of compacted calcined tincal product with increased density in the second step as result of compacting micronized calcined tincal with low density under pressure.
Raw material: Run of tincal mine ore crushed to −50 mm,
Chemical formulation: Na2B4O7.10H2O
Bulk Density: 1.3 gr/cm3
Impurity content: 25-45%
Bulk density: 0.15-0.3 gr/cm3
Particle Size: <250 micron
Impurity content: 3-12%
Chemical formulation: Na2B4O7.(1-5)H2O
Bulk density: 0.75-1.0 gr/cm3
Particle size: <6 mm (size may be adjusted.)
Crystal water: 1-5 mol H2O
Impurity content: 3-12%
The production of micronized calcined tincal with high content of B2O3 is accomplished by the method in which the earth mineral material hardens due to lose of water contained in the ore during calcinations of coarse tincal ore in a rotary furnace with flights, tincal ore has a brittle structure as a result of loss of moisture and water content and consequently expansion, expanded tincal is crushed by autogenic grinding impact of clay hardened in rotary furnace, micronized calcined tincal with low density is purified from the clay (impurities) in a high rate by subjecting to pneumatic separation by means of hot air used for calcination process.
A calcination process is required to produce a micron size calcined tincal having 1-5 moles of crystal water. Interior design of the calcination furnace is important as affecting production quantity and quality. There must be flights swirling grains of ore inside the furnace attached to the liner of the furnace. These flights must be mounted at the interior lining of the furnace along the furnace as strips by intervals.
Inclination and rotation speed of the furnace are among the factors affecting the time for staying within the furnace and thickness of the liner and quantity of supply as well, thus production quantity and quality are also affected.
Preheating of equipment used in process is required prior to start of production.
Coarse tincal ore is prepared for calcination after it was crushed into pieces of −25 mm size; however it may be calcined by being crushed into larger size (−50 mm) Crushed coarse tincal ore is charged into the feeding hopper (1) and the process is put into operation.
The furnace is subjected to preheating by clean air sucked from the ambient air by a fan (8) and a burner (6) with temperature control in a process control manner. Calcination kiln (2.1) is arranged to thermal regime before charging.
According to crystal water rate of micronized calcined tincal to be produced (1-5 moles), operation temperature levels of the process are adjusted to the temperature ranges defined in the following and these temperature parameters are controlled by an automatic control system continuously. So, temperature values in the system are as follows:
After completion of preheating, coarse tincal is fed to calcinations furnace in reverse flow (in the reverse direction of hot air flow) from the exit of the furnace (cold head).
Calcination furnace is an oven with reverse flow, thus supply of coarse tincal ore and flow of hot gas move in reverse direction.
Coarse mine ore is fed gradually by increasing until rated capacity is reached into rotary furnace by a system located under feeding bunker with weight/flow control. Quantity of feeding is determined based on the system capacity.
When operation is performed at the lower values of the defined temperature level, crystal water of final product is 5 moles; when operation is performed at the upper values micronized calcined tincal having about 1 mole crystal water is produced. In order to produce micronized calcined tincal including crystal water with the values between 1 to 5 moles, temperatures of the process must be adjusted to the values between minimum and maximum temperature values. Therefore; these temperature parameters must be controlled continuously by means of an automatic control system.
In addition; in order to produce micronized calcined tincal including crystal water with the desired values according to the process (1-5 moles), it will be convenient to apply heat treatment to coarse tincal in the rotary furnace with flights for 40-45 minutes. Temperature values of the chimney and dust cleaning unit within the process operation temperatures must be adjusted not to exceed the required temperature values for the heat treatment to be applied to coarse tincal in the furnace.
Coarse ore fed into the furnace is calcined after being exposed to heat treatment with removal of surface moisture and crystal water. The internal flights of furnace ensure swirling of the ore after it is raised to a certain height instead being rolled into the furnace and grinding of hardened clays in autogenic manner on expanded calcined tincal.
Calcined tincal ground to micron size by the method employed is forced to be driven toward chimney by air fan. Calcined tincal ground into micron size are separated there in three steps and average 250 micron sized calcined tincal is obtained at the furnace output (chimney) (3), under the dust cyclone unit (4) and under bag filter (5). The products produced in this way are stored in hoppers separately and in mixture as well after they are blended into a mixture. On the other hand, waste clay subjected to separation can not be dragged by fan owing to coarse particle size (−20 mm) and high specific density and taken from the output (2) at the side of the burning chamber of calcinations furnace. The clay with a content of 1 to 5% B2O3 in average is obtained from the output. The air calcined tincal in micron size is discharged into the atmosphere from the funnel (7).
Calcined tincal ground into micron size (−250 micron) and calcined clay are subjected to separation in the furnace using difference of density. Since bulk density (0.15-0.3 g/cm3) of calcined tincal pulverized into micron size is lower compared to calcined clay (1.0 g/cm3), it is conveyed by air flow to dust cleaning unit. Here, air and dust elements are separated from each other; thereby, micronized calcined tincal is stored as final product. Calcined clay is obtained from opening of the furnace because of its high density.
The impurities such as clay obtained from hot head of furnace (furnace entrance) are removed as waste comprising 1-5% B2O3.
First, surface moisture is evaporated upon contact of coarse tincal ore with the hot air inside the furnace and then a part of crystal water in the chemical composition of ore is separated based on temperature and duration to remain inside the furnace, and finally expanded ore blasts.
As the temperature in the dust cleaning unit is low, water removed from the ore and water vapor carried into the system via air and combustion gases in the dust cleaning unit condense. A part of condensed water vapor is absorbed by the micronized calcined tincal again and included by the same; thus increase in the crystal water in the body is seen.
During production by this method, important parameters requiring attention are as follows:
By this invention, a new product called “micron sized calcined tincal”, with average values of impurities, 50-58% B2O3 content, 1-5 moles of crystal water, size of −250 mm, bulk density of 0.15-0.3 g/cm3 and 10 to 15% insoluble material content is produced ensuring temperatures of the process, and enriching basic run of mine of tincal ore with a maximum particle size of −25 mm, 20 to 28% content of B2O3 and 10 moles of crystal water, with a recovery of B2O3 content in a method of calcination and autogenic grinding and separation (CASG) in a single step.
In the second step, the method for production of compacted, calcined tincal with increased bulk density is invented by compressing micron sized calcined tincal with low density between rotating discs (plates) under pressure followed by crushing, sieving and adjusting size of the product. The method has been applied in industrial scale.
Calcined tincal with average size of −250 micron and 0.15-0.3 g/cm3 bulk density is conveyed from stock silos to coarse sieve (11) by the elevator (9). After sieving, it is conveyed to magnetic separator (23) by the conveyor (13). Following separation of magnetic particles, it is transferred to wetting system (17) where it is humidified at required rate and then conveyed to feed bunker (21) for compactor.
Humidified, calcined tincal in micron size is conveyed from compactor feed bunker to rotational discs of compactor (24). Cycles of helical supply system and those of compactors discs are well adjusted. Pressure applied to discs is also adjusted and these adjustments are designed to permit checking.
Calcined tincal entering in between compactor discs in micron size is extracted by the discs as compacted in slabs. The product extracted in slabs is crushed by the front crusher (19) coupled to compactor and then fed into size adjusting crusher (20). Compacted calcined tincal is carried by the conveyor (18) and elevator (10) to product screen (12) and sieved here. The product remaining on top of the screen is fed by the conveyor (16) back to crusher (20) to be crushed to size. The product passing through screen is fed back to the inlet of compacting system by conveyor (14). The medium sized product gathered in between layers of sifter is conveyed to product silo (22) by the conveyor (15) and prepared for sale after they are packed in bags in the packing unit (25). It is possible to adjust pressure value and mesh size of the screen by selection depending on bulk density and particle size of final product.
In order to increase amount of production in the compacting studies and to produce compacted calcined tincal at desired spec values, bulk density (0.15-0.3 g/cm3) is to be increased to level of 0.4-0.6 g/cm3 in average by applying pre-condensation process before entering into the compactor.
To meet this end:
In this way, air included in the micronized calcined tincal is discharged, thus dust is enabled to be inserted in the compactor by getting small in volume and compressed the dust with the bulk density of 0.4-0.6 g/cm3 in average.
Air included in the micronized calcined tincal and one of the reasons affecting negatively the compacting efficiency is discharged; thereby, the micronized calcined tincal pre-density of which is increased is compacted as a result of high pressure applied on it.
The micronized calcined tincal absorbs the water provided from the outside for bounding in order to increase the compacting efficiency of the micronized calcined tincal, which results in an increase in crystal water. However, in case the product is given in the rate of 1% by weight, it is not caused a significant increase in the crystal water of the product and remains between the desired tolerance values (Table 1).
Moreover, micronized calcined tincal has exothermal reaction when it contacts with water, which results in absorbing the water provided in pulverized manner as well as creating heat. This heat increase causes evaporation of a part of the water provided. The more water is provided the more increased in the crystal water is seen. Increase in the crystal water amount also increases the compacting efficiency of the micronized calcined tincal.
In the industrial applications for the micronized calcined tincal, when compacting process is performed without increasing pre-density of the product, compacting efficiency will be low. In this case, when compacting is preferred to be performed in a single step at least 15 ton/cm pressure to be applied on disc surfaces is required. However, as mentioned above, compacting process carried out with at least 4 ton/cm pressure to be applied on the disc surfaces in the 2nd step by increasing the density of the product by removing air in the product in the 1st step results in compacting in higher efficiency and capacity.
The change in physical characteristics of compacted, calcined tincal products obtained by compacting micron sized calcined tincal is as follows.
By this invention production of a new product called “compacted, calcined tincal” with particle size of −6 mm, bulk density of 0.75-1.0 g/cm3 and the same chemical properties with the micronized calcined tincal is achieved by compacting method using micron sized calcined tincal with particle size of −250 micron and bulk density of 0.15-0.3 g/cm3 as the raw feeding material.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006/05914 | Oct 2006 | TR | national |
| 2007/03372 | May 2007 | TR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IB07/54225 | 10/17/2007 | WO | 00 | 10/13/2010 |
