RU2254402C1 - Method of transportation of raw material - Google Patents

Abstract

FIELD: non-ferrous metallurgy; raw material unloading and transportation complexes for electrolytic production of aluminum delivered to plants by railway transport facilities equipped with low-discharge cars.

SUBSTANCE: proposed method includes loading alumina from rolling stock into receiving bins, delivery of alumina from receiving bins to bin of gas-cleaning units, distribution of alumina by means of centralized distribution system and unloading of fluorides from rolling stock to bins of technological cranes. Unloading alumina from rolling stock is performed by means of aerochutes on unloading trestle mounted under electrolyzer bodies; centralized distribution of aluumina in automated delivery bins is performed by means of conveyers in form of "fluidized bed" or in "dense phase". Unloading fluorides from rolling stock to service bins is performed on unloading trestle; service bins are located above electrolyzer bodies; loading the material to bins of technological cranes is effected by gravity. Return electrolyte from collecting bins located above unloading trestle is additionally transported to service bins located above electrolyzer bodies and then to bins of technological cranes by gravity.

EFFECT: reduced number of transportation stages; reduction of grinding and losses of material; reduction of emissions of toxic components into atmosphere.

2 dwg, 2 tbl

Description

The invention relates to non-ferrous metallurgy, in particular to complexes for unloading and transportation of raw materials for the electrolytic production of aluminum supplied to enterprises by rail in cars with lower unloading, and can be used in the design and construction of aluminum plants.

A known method of transporting alumina and fluoride salts used at the Sayan Aluminum Plant (Technical and Economic Bulletin of JSC "KrAZ", No. 4, 1996, p.23-25). The method includes unloading alumina into the receiving silos of the alumina warehouse, fluoride salts from the rolling stock in a separate room and moving the alumina to the receiving silos block. Then the direction of the alumina to the separation of foreign inclusions and to the buffer tanks of gas treatment plants and from there to the centralized distribution of alumina to the bunkers of the automated supply of alumina. Fluoride salts are loaded into the hoppers of process cranes.

The method adopted for the analogue and prototype.

Alumina storage is the first link in the process chain. It is a complex set of equipment with a high degree of mechanization and automation of raw material transportation processes. Alumina unloading from wagons is carried out gravitationally in the hoppers of the receiving device. Further, alumina is transported by compressed air using chamber pumps through pneumatic circuits to the receiving silo block. Dust removal of the wagon unloading place is based on the suction of the entire receiving device due to the organization of air intake at the end of the building in the amount of 100,000 cubic meters per hour and its transportation to the +27 m mark with distribution across an odd group of silos. Excess air from the receiving silo block undergoes a two-stage purification first on high-speed cyclones, then on bag filter units with a regeneration system. An automated chamber pump control system provides for the regulation of parameters necessary to optimize the process of transporting raw materials of various particle size distribution. It includes the functions of preventing the formation of “traffic jams” during the movement of raw materials through the pneumatic pipelines, monitoring the state of the actuators of the chamber pumps, monitoring the flow of process compressed air while the chamber pumps are operating at the same time, regenerating the bag filters of the suction units of the receiving silo unit, and generating event messages.

External conveyor transport has 86 units of equipment, which is built in a sequential technological chain. From receiving silos, alumina is fed through aerating chutes through a metering device to a conveyor belt and transported to a transfer tower, where foreign inclusions are separated into a waste bunker on a screen. Then, using reversible flaps, the raw materials are sent through a chain of conveyors and aeration channels to the receiving hoppers of the gas treatment plants, from which they are transported by pneumatic transport to the buffer tanks of the gas treatment plants. At all reloading towers, there are hose-type suction units for dust removal of raw material transshipment sites. From the fluorinated alumina bunker, the raw materials are transported by pneumatic transport to the bunker bunkers, and then by pneumatic transport to the bunkers of the automatic feeding of alumina into the electrolyzer. An automated control system for external conveyor transport is carried out through a programmable controller with the functions of controlling technological equipment, collecting, processing and storing technological information, monitoring the parameters of mechanisms, generating event messages.

The disadvantages of this method are:

The presence of a large amount of equipment, multi-stage and sequence of transport operations, the use of rubber conveyor belts related to the category of highly combustible materials, the need to use an automated control system, increased risks of providing raw materials for aluminum production.

Grinding of raw materials during transportation, especially in areas where high-pressure transport is used, leads to an increase in losses in gas treatment plants and, as a result, to environmental pollution.

The choice of pneumatic high-pressure transport during the construction of aluminum smelters was justified by the production of small "powdery" alumina by domestic manufacturers. Improving the technology of aluminum production primarily places high demands on the quality of raw materials. Many alumina refineries have adopted investment programs aimed at improving the technology and producing a larger “sandy” type of alumina with a granulometric composition. The use of such alumina sharply reduces the pneumatic conveying capacity, increases the consumption of compressed air and places higher demands on the automation system of the raw material transportation process.

The transition of domestic aluminum smelters, using pneumatic high-pressure transport of alumina as the main one, to the use of sand-type alumina requires significant operational costs, primarily due to a decrease in the performance of chamber pumps and an increase in the consumption of compressed air, which is an expensive form of energy.

The objective of the invention is to reduce operating and capital costs for the construction of new aluminum plants, reducing the number of transport equipment. The technical result of the invention is to reduce the number of stages of transportation of raw materials, reduce grinding and loss of raw materials, reduce the risks of providing raw materials for aluminum production, reduce emissions of pollutants into the atmosphere.

The technical result is achieved by the fact that in the method of transporting raw materials for the electrolytic production of aluminum, including unloading alumina from the rolling stock into receiving hoppers, feeding it from the receiving hoppers to the hoppers of the gas treatment plants, then distributing it to the bunkers of the automated feeding of alumina through a central distribution system, unloading fluoride salts from the rolling stock to the bunkers of technological cranes; unloading of alumina from the rolling stock is carried out according to the system of aerial chutes on the river loading ramp installed above the electrolysis casings, into the receiving bunkers under the viaduct located between the electrolysis casings, centralized distribution to the automated feeding silos is carried out by alumina conveyors in the form of a "fluidized bed" or in the "dense phase", fluoride salts from the rolling stock are unloaded at the discharge overpass to consumable bins located above the electrolysis housings and then to the bins of technological cranes under the action of gravity, additionally transport return crushed electrolyte from storage bins located above the discharge overpass, a feed hopper located above housings electrolysis, and then - in the process cranes hoppers by gravity.

The proposed method, in comparison with the prototype, completely eliminates the loading of raw materials into the alumina warehouse, which consists of buildings, galleries, reloading towers, receiving devices, a silo unit with aspiration systems, a complex of equipment with automated control systems. A compressor station with equipment, cooling towers, a water recycling system, overpasses, and pipelines is also excluded.

A significant reduction in the technological chain of transportation of raw materials, the exclusion of complex, sequential conveyor transport systems, energy-intensive pneumatic systems will significantly reduce the risks of providing aluminum production with alumina, and reduce operating costs by 15 times. The exclusion of high-pressure transport from the technological chain will significantly reduce the grinding of raw materials and will make it possible to fully use the geometric volume of silos and bins for storing raw materials.

The method is illustrated by drawings, where Fig. 1 shows a system for unloading raw materials from an overpass, and Fig. 2 is a diagram of galleries for unloading raw materials.

The system for unloading raw materials from a flyover includes an unloading gallery 1, silos for alumina 2, consumables for fluorine salts and crushed electrolyte 3, aero chute 4, a centralized distribution system for alumina 5, and a hopper for process cranes 6.

To implement the method, an increase in the level of railway tracks to an overpass located at a height of 18-20 meters, passing over the buildings of electrolysis buildings, parallel to the axis of the connecting corridor. Raising the level of railway tracks to the level of overpasses is carried out by filling the soil removed during the planning of the industrial site, or by choosing a site for the construction of a plant with a natural relief increase.

The amount of soil needed to fill the railway bed to a level of +20.00 m is 680,000 m ³ , this is the amount of soil taken out with a vertical layout of the site 2000 × 2000 m by 0.17 m. The capacity of one silo for alumina is 7000 tons, which geometrically corresponds to a cylinder with a diameter of 24 m and a height of 17.5 m.

The “route” arriving at the plant with alumina, which consists of 55 “hopper” wagons and has a total length of 600 meters, is divided into two equal parts and is set for unloading at the same time in two galleries. Unloading of raw materials from cars is carried out with shifts directly to the bins of fresh alumina and buffer tanks of gas treatment plants for aeration channels, which allow the simultaneous unloading of three cars in one bunker. The separation of foreign inclusions in the discharged raw materials takes place on a sieve installed in the discharge gallery in front of the aerial chute. The number of permutations of cars is determined by the number of batches of electrolysis.

The transportation of raw materials to the bunkers of the automated supply of alumina to the electrolyzer is carried out by conveyors of the "fluidized bed" or in the "dense phase" directly from the bunker of fluorinated alumina gas treatment plants.

The supply of fluoride salts to the plant is carried out in bulk in cars with lower unloading, which will ensure minimal costs for transshipment of raw materials, reducing the cost of raw materials by reducing the costs of supplying plants for packaging, packaging and loading operations.

Storage of fluoride salts is carried out in a mobile warehouse consisting of wagons with lower discharge. The construction of a receiving device for storing raw materials in bag packaging is not required. This will reduce the cost of loading and unloading operations and load all fluoride salts into electrolyzers using technological cranes. The movement of these cars in the discharge gallery to fill the consumable bins in the electrolysis bodies is carried out using a tractor car. If necessary, fluorine salts are reloaded from incoming cars to hoppers of in-plant vehicles by gravity from the unloading gallery. Incoming fluorine salt wagons can be used as a mobile warehouse of fluorine salts; in this case, the cost of transshipment, as well as the transshipment of raw materials, is not required.

The crushing section of the circulating electrolyte involves the installation of storage bins of crushed raw materials above the discharge gallery, which will allow for the delivery of raw materials to consumable bins for refueling process cranes according to the above option.

In the proposed option, the issues of filling the hoppers of technological cranes with covering material for anodes are solved, which according to technological requirements should contain a large fraction of electrolyte up to 10-15 mm. Due to the increase in the front of unloading wagons, the maximum unloading time for alumina and fluoride salts will be 20% of the total time stock. This gives reason to consider the flyover as a potential opportunity for transporting the anodes between the anode production workshop and the electrolysis bodies.

Table 1 shows a comparative analysis of the cost of the proposed method for unloading and transporting the prototype, which shows (see table 2) that construction costs are reduced by more than two times, and operating costs by more than ten times.

Claims (1)

A method of transporting raw materials for the electrolytic production of aluminum, including unloading alumina from rolling stock to receiving bins, feeding it from receiving bins to bins of gas treatment plants, then distributing it to bunkers of automated feeding of alumina through a centralized distribution system, unloading fluoride salts from rolling stock to technological bunkers cranes, characterized in that the unloading of alumina from the rolling stock is carried out according to the system of aerial chutes at the unloading trestle, installed above the electrolysis housings, into receiving hoppers under the overpass located between the electrolysis housings, centralized distribution to the automated feeding hoppers is carried out by alumina conveyors in the form of a "fluidized bed" or in the "dense phase", fluoride salts are unloaded from the rolling stock on a loading ramp to consumables hoppers placed above the electrolysis bodies and then into the hoppers of the process cranes under the action of gravity additionally transport return crushed electrolyte and collecting hoppers disposed above the discharge overpass, a feed hopper located above housings electrolysis and then - in the process cranes hoppers by gravity.

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