CC BY
8
AZ9RBAYCAN KÍMYA JURNALI № 1 2016
39
UDC 66.099.2
STUDY OF GRANULATION OF TITANOMAGNETITE CONCENTRATE PRODUCED FROM ADZHINAUR SANDSTONE WITH FLUX SODA ADDITIVE
Z.I.Alizade, A.N.Mammadov, A.M.Qasimova, G.M.Samedzade, O.Sh.Abdulragimova,
T.A.Isachenko, U.N.Sharifova
M.Nagiyev Institute of Catalysis and Inorganic Chemistry NAS of Azerbaijan
[email protected] Received 07.10.2015
The conditions of granulation titaniferrous concentrate obtained from Adzhinaur sandstones magnetic separation, with a flux additive 25% soda. The optimal conditions of the process: the speed of rotation of the drum granulator, amount of water required for granulation, and the strength of the obtained granules, the temperature of roasting for following reduction by natural gas.
Keywords: titanmagnetite concentrate, drum granulator, rotational speed, granules stability.
Introduction
In Adzhinaur initial target sandstones the content of useful components is: Fe - up to 1315%, TiO2 - up to 2.3-3.0%, V - up to 0.6%, Mn - 0.7% [1]. Removing titanomagnetite concentrate from sandstones Adzhinaur is carried out relatively on easily pulverized fraction - 0.1 mm. The content of target components is Fetotal - up to 54%, TiO2 - to 7.0%, V - to 1.0%, and fineness is less than 0.1 mm at a secondary separation. Due to the difficulties in the recovery of fine concentrates, natural gas layer, fine concentrates undergo balling to obtain pellets of ore for the recovery in the filter bed and recycling.
In the processes of recovery of iron and titanium magnetite concentrate pellets with natural gas is an ideal raw material since the filter layer is provided strictly constant throughout the volume of the gas permeability and uniform distribution of the gas flow. Balling thin concentrates in addition to good permeability helps to eliminate dust discharge pellet fines and improve their reduction.
When seaming titanomagnetite concentrates from Adzhinaur sandstones with a flux additive pre-prepared mixture of concentrate with 25% anhydrous soda after thorough mixing was balling in a laboratory drum pelletizers with diameter of 150 mm. The binder used water, pulling together the particles of powdered concentrate in clumps and the consequent enlargement of pellets at balling. Spraying water ensures agglomeration of fine particles and laminating the surface formed in a moving bed of nuclei.
Our studies [2, 3] have shown that in the reduction process of the natural gas pellet concentrates multifunctional additive in alkaline fluxing pellets titanomagnetite concentrate contributes to reducing the activity of methane and its degradation products prevents the formation of an abundant black carbon and iron carbides and creates the possibility of separating titanate, vanadate, chromite and other compounds and complete separation of metallic iron from the oxide phase. Along with the improvement of a number of technological parameters of the process, flux additives, such as by binding the impurity components of the concentrate and increase the purity of the powder discharge, and by passivating the surface of the dispersed particles of iron and prevent corrosion, improve the quality of final products.
Experiments
Granulation of the resulting concentrate Adzhinaur sandstones was investigated in a laboratory tumbling granulator drum diameter 150 mm diagram is shown in Fig.1.
The drum is a tin cylinder 1 150 mm in diameter and 75 mm in length with rods and pins 2, non-slip granulated material on the inner surface of the drum. The back side of the drum head is attached to the flange 3 fixed to the axis 4. Axis installed in two bearings, mounted respectively on two pillars 5. Axle gear planted 6, by which the rotation of the reduction gear 7 and motor 8 is transmitted axis of the drum.
Figure 1. Drum granulator: 1 - drum, 2 - rods and pins, 3 - flange, 4 - axis, 5 - bearings in supports, 6, 6 - gear, 7 - reduction gear, 8 - engine, 9 - support, 10 - the angle a of inclination of plate of drum to the vertical, 11 - hopper.
The speed of rotation of the drum is one of the determining factors of the granulation process. As for the literature on the granulation of pulverulent materials, there is a concept of the critical speed of the drum, when developed by the centrifugal force reaches a value at which the granulation mass is pressed against the drum shell and rotates with it as one unit [4].
This rate is calculated by the formula:
««it = "V^,
ncrit - critical speed of rotation of the drum, rev/min; g=9.8 m/s - acceleration of gravity; R -radius of the drum, m.
For our granulator at R = 0.075 m, the speed will be ncrit= = 109.2 rev/min.
When the speed is somewhat less critical granules fall from the upper position into the lower part of the drum on the parabolic curve, and the maximum speed at which the granules start to roll on the surface of the underlying layer is calculated by the formula [5]:
30 -_
-•xfe/3R, «limit= 63.03.
«limit _ '
П
This rate may be called the maximum limit for granulation. Set of gears picked slightly greater bow l speed equal to n1=72 rev/min.
At target rotation speed of the drum we observed intensive rolling of grains with simultaneous sliding of granulated material. To prevent slipping on an inner surface of the drum set of wire rods of 1.5 mm diameter in an amount of 4 pieces. Installed rods prevent slipping, while watching intense turbulent rolling granules, and some of the granules rose up and fell into the bottom of the drum. This did not have time to get stronger pellets crumbled. Thus, the speed of rotation of the drum studied after exclusion of possible simultaneous sliding been overstated.
To improve the granulation process, the transition from turbulent to laminar rolling granules decided to reduce the speed to 1/2 nlimit = 1/2-63 rev/min = 31.5 rev/min. However, the rotation speed for set of gears is 27 rev/min. At this rate we observed intensive laminar rolling pellets without jumps. At the same time, we replaced the rods pins by setting them in a checkerboard pattern, which contributed to the granule. This speed is 27 rev/min at 150 mm in diameter pellet taken for the optimum.
By establishing an optimum drum rotation speed was determined by the remaining parameters, which would produce perhaps strong granules (amount pulverized water while rounding the obtained pellets, change in the strength of pellets during storage, the effect of calcination temperature on the strength of the obtained pellets and others.) Magnetite concentrate from adzhinaur sandstones with additives is 25% of soda.
Granulation was prepared by mixture, it was carried out as follows: the prepared material filled in a rotating drum and pour the surface of the bulk material sprayed with water. The resulting small green pellets sprinkled with a new portion of powder with simultaneous spraying of water. As soon as most of the pellets reached 3-5 mm supplying dry concentrate stops. Occasionally spraying the pellets, they are not waterlogged, surface sloshing continued 10-20 min.
Studies have shown that increasing pelletizing of time up to 30 min and more increase does not the strength of the green pellets. Thus, when the diameter of the granules 5 mm sloshing over 15 min substantially doesn't effect the strength of green pellets and crushing is at 50 g/granule.
Thus obtained granules were sieved through a ~3 mm and poured on the desktop for a natural drying. Small pellets as retour returned to the drum for palletizing.
Measurement of the strength of the granules crushing carried out on laboratory Fick hardness tester is shown in Figure 2.
Figure 2. Hardness Fick: 1 - cup for fractions 2 - axle, 3 - holder with the guide sleeve, 4 - support, 5 - tile, 6 - granule.
Results and discussion
Granule 6 installed on tiles and it is carefully lowered axis 2 with cup 1, fastened to its upper end. Axis free to move vertically in sleeve holder 3, fortified on a support 4. in the cupl slowly fall asleep until fraction crushing pellets. The total weight of the axis with a cup and a fraction of the ultimate strength of the pellets kg/pellet. We investigated the effect of time on the strength of natural drying quality of the resulting granules, so-called open time of caught formed granules. Determination of pellet strength according to the drying time after l, 2, 3 or more hours are given in Table 1 below.
Table 1. Increase in pellet strength versus time natural
Granule diameter, mm Pellet strength, kg/pellets versus time natural drying, hour
0.5 1 2 3 24 48
3.5 0.200 0.650 0.65
4.0 0.050 0.08 0.130 0.250 0.75 0.85
4.5 0.300 0.80 0.90
5.0 0.350 1.0 1.25
Studies have shown that pellet strength increases with time, in particular after 3 hours, the most robust pellets appeared with a white coating on the surface of soda. Granule diameter 4 mm 3 hours later collapsed at a load of 0.35 kg/pellet, granule strength during natural
drying increased almost 6-7 times as compared with fresh - 0.5-1 hour to the strength of 50-80 g/granule.
After determining the strength of pellet quality specified amount of water required for granulation. The amount of water measured on the one hand actually expended during spraying, and other refined water being in crude granule maximally saturated with water. This is the limit of saturation, the excess of which leads to blocking of granules, the formation of a solid mass of granulated material. For the first variant was weighed before the start of spray granulation of 45 g sample after the end of the process, including the time of the additional rounding. The amount of water that went to the granulation and its natural loss amounted to 19 g in%, proceed from sample and the water consumed (just 64 g), was 29.7%. The amount of water that went to the granulation (29.7, 29.3, 29.6, 29.4) averaged 29.5%, which is almost 3 times as big as the amount of water required for granulation of magnetite concentrate without soda. This is naturally and is associated with the formation of crystalline soda binding considerable amounts of water.
Reducing the amount of water supplied results in the formation of loose low-strength pellets that even with time do not become stronger. An increase in the amount of supplied water causes the granules to coalesce into a solid mass.
As noted above, the strength of the pellets at natural drying on the table during the first day significantly increases and then increases slightly. In connection with this we determined moisture content of pellets in natural drying desktop through 1, 2, 8 days. At the same time to clarify the amount of water that went to the measured moisture content of granulated granules immediately after granulation. The data obtained are presented in Table. 2.
Table 2. Water loss at natural drying on a table with time
Time Humidity, % Loss of water from initial quantity, % Loss of water from residual, %
0 29.03 0 0
1 24.92, 85.9 4.11, 14.16 4.11, 14.16
2 17.95, 61.8 11.08, 38.70 6.95, 23.84
8 15.06, 51.9 13.97, 48.12 2.89, 9.96
As can be seen from Table 2 granules moisture is reduced by the eighth day almost 50% (48.12) of the amount of introduced water, but the strength of the pellets as discussed above is not reduced, but increases slightly. Thus, the infeed granulation 29% of water is quite optimal and its loss of 14% in a day or 38%, after 2 days does not reduce the strength of the granules.
Since granulation is an intermediate stage prior to firing and subsequent reduction of magnetite concentrate, we investigated the effect of temperature and duration of calcination in the strength characteristics of the concentrate pellets in admixture with an additive 25% of soda. Experiments were performed in a muffle furnace at a temperature range of 600-1000°C. Granules same diameter (4 mm) in porcelain cups held for 30 min at each of the temperatures - 600, 700, 800, 900 and 10000C and, after cooling, their strength has been measured. The obtained data are presented in Table 3.
Table 3. Dependence of granules strength of the temperature and the firing time at a diameter of 4 mm_
Temperature, T°C 25 б00 700 800 900 1000 1100
Time of cake, min - 30 30 30 30 30 б0 30 б0
Granules stability, kg/granule 0.7 0.050 0.0б0 0.050 0.080 0.50 1.8 0.7 2.7
Conclusion
Proceed from strength characteristics of the calcined granule shows that on heating from 600 to 9000C granules strength is sharply reduced from 0.7 kg/granule of the raw 0.0500.080 kg/granule at calcined. Obviously the calcination of hydrated soda-magnetite complex
leads to complete destruction of temperature rise and the new ties are formed. At 1000 and 11000C granules strength increases 30 min respectively to 0.5 and 0.7 kg/granule, and an hour later it reaches 1.8 and 2.7 kg/granule, respectively. It is obvious that at a high temperature of 1000 and more granules 11000C sintering occurs, while 11000C sintering occurs at the points of tangency of certain individual granules. In this regard, on the basis of the data obtained for the optimum, taking the temperature of the calcination at a time 45-60 min is equal to 1000°С.
REFERENCES
1. Ализаде З.И., Микаилова А.М., Самедзаде К.М., Исаченко Т.А., Абдулрагимова О.Ш. Обогащение Аджинаурских железоносных песчаников с получением титаномагнетитовых концентратов для комплексного использования. // Азерб. хим. журн. 2008. № 4. С. 64- 67.
2. Ализаде З.И. Разработка технологии комплексной переработки прибрежных и шельфовых россыпных титаномагнетитов // XVI Менделеевский съезд по общей и прикладной химии. Сб. № 2: Состояние и развитие производства химических продуктов. Москва. 1998. C. 7-8, 208209.
3. Ализаде З.И., Шахтахтинский Г.Б., Садыхов Г.Б, Касумов К.А., Абдулрагимова О.Ш., Мир-зоев А.Х. Способ переработки титаномагнетитовых концентратов морских песков. Ах. № 801579. СССР. 1981.
4. Першин В.Ф., Однолько В.Г., Першина С.В. Переработка сыпучих материалов в машинах барабанного типа. М.: Машиностроение. 2009. C. 225.
5. Адыгезалов Х.М., Самедзаде К.М., Байрамова С.С. О предотвращении запыления окружающей среды грануляцией пылевидных материалов // Тезисы докл. научн. конф., посвященной 100-летнему юбилею академика М.Ф.Нагиева. Баку. 2008. С. 24-25.
ACINOHUR QUM DA§LARINDAN ALINMI§ TÍTANMAQNETÍT KONSENTRATININ FLÜS NATRiUM KARBONAT OLAVOSÍ ÍLO DONOVORLONMOSÍNÍN TODQÍQÍ
Z.LOlizada, A.N.Mammadov, A.M.Qasimova, Q.M.Samadzada, O.^.Obdülrahimova, T.A.isaçenko, U.N.Çarifova
Acinohur qum daçlanndan ahnmiç titanmaqnetit konsentratinin baraban tipli danavarlaçdiricida 25% natrium karbonat alavasi ils, su ils danavarlaçmasinin tadqiqi aparilib. Flûslaçmiç danavarlarin alinma çaraiti: barabanin firlanma sürati, suyun miqdari, danavarlarin barkliyi, danavarlarin yandirma çaraiti va sonradan tabii qazla reduksiya ûçûn öyranilib.
Açar sözlzr: titanmaqnetitli konsentrat, baraban tipli dsnsvsrlsçdirici, firlanma sürati, danavarlarin davamliligi.
ИССЛЕДОВАНИЕ ГРАНУЛЯЦИИ ТИТАНОМАГНЕТИТОВЫХ КОНЦЕНТРАТОВ, ПОЛУЧЕННЫХ ИЗ АДЖИНАУРСКИХ ПЕСЧАНИКОВ С ФЛЮСОВЫМИ ДОБАВКАМИ СОДЫ
З.И.Ализаде, А.Н.Мамедов, А.М.Гасымова, Г.М.Самедзаде, О.Ш.Абдулрагимова, Т.А.Исаченко, У.Н.Шарифова
Исследованы условия грануляции титаномагнетитового концентрата, полученного из Аджинаурских песчаников магнитной сепарацией, с добавкой 25% соды в качестве флюса. Установлены оптимальные условия процесса: скорость вращения барабана гранулятора, количество воды, необходимое для грануляции, прочность полученных гранул и температура их обжига для последующего восстановления природным газом.
Ключевые слова: титаномагнетитовый концентрат, барабанный гранулятор, скорость вращения, прочность гранул.
