RU2040758C1 - Furnace charging device of fluidized bed for roasting of molybdenum concentrate - Google Patents

Abstract

FIELD: metallurgy. SUBSTANCE: charging device uses a receiving hopper; feeder, thrower and a chute, attached to whose bottom part is an air dissector with nozzles positioned in rows at an angle of 5 to 10 deg to one another, the relation between the dissector width and height being 1:(0.2 to 0.5). The use of the air dissector provides for distribution of the jet of charged material, uniformly over the entire surface of fluidized bed, which ensured a stable uniform charging of roasted material by air stream. EFFECT: production of roasted material suitable for reroasting in a multihearth furnace with production of material containing not more than 0.1% of sulphur. 3 dwg

Description

 The invention relates to metallurgy, in particular to structural elements of fluidized bed furnaces, and more particularly to the design of a loading device of a fluidized bed furnace for roasting molybdenum concentrate.

 Currently, fluidized bed furnaces use a loading device, which represents a rotating disk with an engine, over which a hopper for fired material is located. In the lower part, a heat is attached to the rotary disk, through which the calcined material enters the fluidized bed furnace.

 The disadvantage of the used loading device in a fluidized bed furnace with unloading of material by an air stream is the uneven loading of material on the surface of the fluidized bed, which leads to the production of calcined material of uneven composition and poor quality due to the fact that the material is removed along the entire surface of the fluidized bed.

The current loading device design is acceptable for fluidized bed furnaces with bottom discharge of material. With local loading of the material, its new portions, immersed in a fluidized bed, are fired with a high content of S ⁺⁶ in the upper layers, which are carried out of the furnace by air flow. In the material taken out, the ratio S ⁶⁺ / S ^{3 is} less than 4. This material cannot be annealed in the 2nd stage in a multi-hearth furnace.

 The following types of boot devices are accepted as analogues.

 The loading device of the incinerator for waste, containing a housing with a loading hole, a gate, a movable table and a pusher with a hydraulic cylinder.

 A loading device with a rotating hopper, including a skip hoist and a loading mechanism with a rotating hopper.

 A loading mechanism comprising a receiving funnel, a two-valve shutter of an intermediate container, a lower funnel and a distribution tray mounted on a rotary shaft.

 The disadvantage of analogue loading devices is that the material is fed in a concentrated compact stream into a small limited surface area of the fluidized bed.

 As a prototype adopted boot device spreader containing the receiving hopper, thrower and estrus.

The disadvantages of the prototype are local loading of material in a small volume of the furnace, the heterogeneity of the jet according to the saturation of the material over the cross section of the fluidized bed furnace, the low quality of the calcined material in terms of S ⁶⁺ , reducing the ratio S ⁶⁺ / S ³ - less than 3.5. The pre-firing of such material at the 2nd stage ends with a high sulfur content.

The essence of the invention lies in the fact that the air divider attached to the lower part of the estrus is equipped with nozzles located at an angle of 5-10 ^about each other with a ratio of the width of the divider to its height 1: (0.2-0.5). This allows, during the operation of the thrower, to distribute the stream of feed material evenly over the entire surface of the fluidized bed in the fluidized bed furnace, which ensures stable uniform loading of the calcined material with an air stream.

The proposed device provides for obtaining a calcined material with a ratio of S ⁶⁺ to S ^3- equal to 4-10, suitable for firing in a multi-hearth furnace to obtain a material containing not more than 0.1% sulfur.

The loading device includes a receiving hopper 1 for receiving material, intended for firing in a fluidized bed. Under the receiving hopper is a feeder 2 with a device that sets the feed rate of the material. Below the feeder is a thrower 3, which is a drum, on the shaft of which metal elements 4 are attached to capture material and feed it into estrus 5. An air divider 6 is attached to the lower part of the estrus with nozzles 7 located at an angle of 5-10 ^about each other with the ratio of the width of the divider to its height 1; (0.2-0.5).

 The loading device is installed on a fluidized bed furnace operating in the mode of unloading the calcined material by air flow, and is attached to the furnace body.

 The boot device operates as follows.

 The calcined material, loaded into the receiving hopper, is fed by a feeder into the thrower, which throws the material through the heat into the working space of the fluidized bed furnace. When exiting from estrus, the material is broken by air supplied through a nozzle divider. Due to their location at an angle to each other with air jets from nozzles, for a given ratio of the width of the divider to its height, the material supplied in the form of a jet is distributed over the entire surface of the fluidized bed. In this case, the material is calcined in suspension and introduced by air flow into the gas purification system, where it is captured and sent to a multi-deck furnace for after-burning.

The material calcined in a fluidized bed furnace contains sulfate and sulfide sulfur in a ratio of 4-10, which provides for further firing in a multi-hearth furnace to produce oxidized molybdenum concentrate with a sulfur content of not more than 0.1%
The efficiency of the loading device is achieved by installing an air divider with nozzles located at an angle of 5-10 ^about each other with a ratio of the divider width to its height 1: (0.2-0.5).

If the nozzle angle to each other is less than 5 ^° and the ratio of the divider width to height is less than 1: 0.2, then a compact stream and local loading of the material into the fluidized bed are maintained, at which substandard material is obtained by the ratio of sulfate sulfur to sulfide.

If the nozzle angle to each other is more than 10 ^° and the ratio of the divider width to its height is more than 1: 0.5, then the material does not have time to burn in a fluidized bed and the resulting material contains sulfide sulfur in an amount exceeding the permissible concentration.

 Figure 1 presents a diagram of a boot device; figure 2 air divider; figure 3 section aa in figure 2.

 On a commercial fluidized bed furnace, the proposed loading device for preliminary roasting of molybdenum concentrate with sublimation of rhenium and unloading a cinder containing sulfide and sulfate sulfur was tested. The resulting cinder was used for after-firing in a multi-hearth furnace.

The loading device consists of a receiving hopper with a capacity of 3 m ³ for molybdenum concentrate, a vibratory feeder, a housing with a thrower equipped with a 5.5 kW electric motor. The thrower is made in the form of a rotating shaft with a diameter of 200 mm, on which wire brushes are located. A heat is located between the thrower and the fluidized-bed furnace, to the lower part of which a 400 mm wide air divider is attached with nozzles in the form of tubes located at an angle of 7 ° ^to each other. Nozzles are located in 3 rows on horizontal planes. In each subsequent row, the nozzles are offset with respect to the nozzles of the previous row.

 The ratio of the width of the divider to its height is 1: 0.35.

 Compressed air was supplied to the divider with a pressure of 4 atm.

 The boot device operates as follows.

 Molybdenum concentrate was loaded into a receiving hopper and fed to a thrower using a vibratory feeder. When the shaft rotates, the thrower wire brushes threw molybdenum concentrate through the estrus into the fluidized bed furnace. The jetted concentrate stream was dispersed by compressed air entering through the nozzles over the surface of the fluidized bed.

 During the operation of the fluidized bed furnace with the proposed device, 95% of the calcined molybdenum concentrate was discharged from the furnace by air flow into the gas purification system, where it was captured and then sent for additional firing to a multi-hearth furnace.

 According to the prototype, a loading device was used on a fluidized bed furnace, including a receiving hopper, feeder, thrower and estrus connected to the furnace body.

 When the loading device was working according to the prototype, it was visually seen how the stream of molybdenum concentrate was directed to one place of the fluidized bed and the loaded material was almost completely immersed in the fluidized bed.

 During the operation of the proposed loading device, it was visually noted that the material evenly spreads over the surface of the fluidized bed.

The performance of the loading devices of the fluidized bed furnace of the proposed and prototype are shown in the table, from which it follows that the fluctuation of the sulfur content in the calcined material during operation of the proposed loading device is characterized by stability, and also that the ratio of S ⁶⁺ and S ^3- is in the required limits for pre-baking in a multi-hearth furnace to obtain a molybdenum oxide concentrate with a low sulfur content (not more than 0.1%).

Claims (1)

LOADING DEVICE OF A BOILER FURNACE FOR FIRING A MOLYBDENUM CONCENTRATE, containing a receiving hopper, feeder, thrower and estrus, characterized in that it is equipped with an air divider attached to the bottom of the estrus with nozzles arranged in rows at an angle of 5 ^{° to} 10 ^{° to} each other with respect to each other divider height 1 (0.2 - 0.5).

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