JPS5836271B2 - Air flow drying method for fine ore - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an energy-saving method for drying copper concentrate having a water content of about 7% after beneficiation treatment, during material transfer to the vicinity of a smelting furnace. The present invention relates to a method of flash drying that is efficient and effective.

When applying the flash drying method to drying powdered ore containing moisture, the main issue is to reduce fuel costs when combustion gas is used as the drying medium gas.

One method is to reduce exhaust gas heat loss by lowering the gas/ore ratio.

The calculated values are listed in Table 1.

However, (calculated assuming heat loss 15%, moisture in ore 7%, and outside temperature 15°C.

) As can be seen from this table, reducing the unit gas amount and increasing the flash dryer inlet gas temperature reduces the fuel consumption rate and makes it possible to save energy.

(1) Although it depends on the type, particle size, moisture content, etc. of fine ore, there is generally a risk of ignition when the temperature exceeds 350°C.

(2) In order to efficiently transport fine ore by airflow at the same time as drying,
A gas amount of about 1000 to 1300 Nm3 is required per ton of ore.

(3) As the dew point of exhaust gas increases, problems such as corrosion and adhesion of fine ore during the exhaust gas treatment process increase.

Therefore, when drying fine ore by airflow, due to these constraints, even if we try to limit the drying air volume per unit of ore from the viewpoint of fuel consumption as described above, In reality, it is necessary to ensure that the limit value or more is exceeded.

Moreover, the cross-sectional area of the flash drying tube must be determined with sufficient margin so that the capacity of this equipment matches the maximum capacity that is foreseen for the future of the entire smelting system.

Therefore, during normal operation or low-load operation, the amount of ore to be dried is less than the specified capacity.
As the amount of passing air must be maintained, it is inevitable that the amount of air flowing per unit of ore will increase.

Therefore, in conventional operation, this increase in air volume resulted in a decrease in thermal efficiency and an increase in fuel consumption.

The purpose of the present invention is to overcome this limitation, and more specifically, in the conventional flash drying method for fine ore, the combustion gas air volume is lowered and the inlet gas temperature is increased in order to keep the fuel consumption level below the fuel consumption rate. However, this could not be achieved due to reasons such as (1)-{3) mentioned above as well as equipment structure reasons.

To this end, the present invention provides a method for transporting water-laden powder ore by means of an air flow medium, in which the combustion gas of the burner and the fil! The mixed gas is mixed with the duct-containing exhaust gas to obtain a sufficient air volume to transport the fine ore and a temperature sufficient to dry the fine ore during transportation, and this mixed gas is used as an air flow medium for transporting the fine ore. We have developed a method that is characterized by its use as a smelter, thereby effectively achieving the above objectives while making effective use of duct-containing exhaust gas generated at various locations within the smelter.

That is, according to the method of the present invention, in a copper smelter, wet copper ore (fine ore) collected by flotation is taken out of an ore storage bin, and is dried using a flash drying tube using combustion gas from a burner. When transferred to the smelting furnace, duct-containing exhaust gases generated at various locations within the smelter (for example, smelting furnace exhaust gas, heater exhaust gas, and other local exhaust gases generated from the working environment of molten metal and high-temperature materials) are converted into the combustion gas. By mixing, the heat and air volume of this dust-containing exhaust gas are used for drying and transporting the concentrate, thereby reducing the amount of heavy oil used in the burner and reducing the temperature and air volume required for the existing airflow drying pipe. At the same time, it is possible to collectively collect dust from duct-containing exhaust gas generated from various locations.

Hereinafter, details of the method of the present invention will be specifically explained with reference to the illustrated apparatus suitable for carrying out the method.

This device includes a hot air stove 10 for generating combustion gas,
A cage mill 20 disposed on the combustion gas outlet side of the hot air stove 10, a gas flow drying pipe 12 connected at one end to the cage mill 20 and connected to the cyclone 14 at the other end, and an exhaust pipe line 1
6 and a blower 18 interposed therein.

The cage mill 20 is equipped with an ore feed port 24 for supplying powdered ore to be dried, and means 26 for crushing and classifying the supplied powdered ore.

The exhaust system 16 is also equipped with a dust collector 28 having a dust removal function.

On the other hand, the hot air stove 10 includes a combustion chamber 30, a spray device 32 provided at a predetermined position in the combustion chamber 30 for supplying fuel and combustion air, and a spray device 32 for protecting the inner wall of the combustion chamber 30 from overheating. It consists of a passage 34 for supplying cooling air and gas along the wall surface of the combustion chamber 30.

Furthermore, this hot air stove 10 includes a first exhaust gas introduction passage 40 that is provided to open near the outlet of the combustion chamber 30.
and a second opening provided at the outlet of the combustion chamber 30.
a third exhaust gas introduction passage 44 provided to open at the outlet of the combustion chamber 30;
Furthermore, a fourth gas introduction passage 46 provided to open at the outlet of the combustion chamber 30;
Each exhaust gas introduction passage 40, 42, 44 is provided with a conduit 48 for inhaling atmospheric air which is branched from the
, 46 and the conduit 48 are each provided with a damper 41,
43, 45, 47, and 49 are interposed.

These dampers are used as control means for maintaining the temperature of the mixed gas of exhaust gas and combustion gas within a predetermined range, as will be described later.

The first exhaust gas introduction passage 40 is connected to a local exhaust gas generation source 50 (for example, a tap or casting location) within a refinery, for example.

The second exhaust gas introduction passage 42 is connected to a heavy oil combustion steam heater 52.
connected to the exhaust gas outlet.

The third exhaust gas introduction passage 44 is connected to the exhaust gas outlet of the smelting furnace 54.

The fourth exhaust gas introduction passage 46 is connected to the exhaust system 16 of the dryer itself and forms a return passage.

A conduit 48 branched off from the exhaust gas introduction passage 46 has one end open to the atmosphere.

A passage 34 for supplying air or gas for cooling the inner wall of the combustion chamber 30 has one side open to the atmosphere, and has a branch passage 35 which is branched at an appropriate point and connected to the second exhaust gas introduction passage 42. We are prepared.

The present invention is carried out as follows using equipment having such a configuration.

When the blower 18 is driven, each part on the suction side of the blower 18, that is, the cyclone 14, the airflow drying chamber 12,
The entire inside of the dryer, including the inside of the cage mill 20, the drying medium gas supply pipe 22, the inside of the hot air stove 10, and the exhaust gas introduction passages 40, 42, 44, and 46 communicating therewith. Negative pressure is created.

By the generation of this negative pressure, each exhaust gas introduction passage 40, 4
2, 44, and 46 all generate airflow in the suction direction.

Exhaust gas is drawn into each exhaust gas introduction passage 40, 42, 44, 46 from each exhaust gas generation source connected to the respective passage by the suction air flow.

The gas suction amount of each exhaust gas introduction passage is determined by the flash drying pipe 12,
Gas temperatures at various locations including the respective exhaust gas generation sources 50, 52, 54 and the exhaust system 16 of the dryer, as well as the flash drying pipe 12 and each exhaust gas introduction passage 40, 42, 44.
, 46 and the atmospheric pressure conditions.

This control is adjusted in relation to each other because the gas temperatures of the respective exhaust gas generation sources are different.

The intake amount of exhaust gas is controlled and adjusted by operating dampers 41, 43, 45, 47, 49 provided in each exhaust gas introduction passage 40, 42, 44, 46 and each passage of conduit 48.

Although their operation may be controlled by automatic or manual means, the control of the amount of exhaust gas mixed in by these dampers is
In order to maintain the temperature of the mixed gas mixed with the combustion gas from the combustion chamber 30 within a predetermined temperature range, that is, to sufficiently dry the fine ore during the process of being conveyed within the flash drying chamber 12. It is necessary to maintain the temperature within a predetermined temperature range below which ignition of the powder ore does not occur and the dew point of the final exhaust gas does not exceed the permissible value.

This mixture of exhaust gas significantly increases the air volume per unit of ore compared to the case of flash drying using only combustion gas. This can be achieved by controlling the temperature in a predetermined range, and it is possible to reduce the fuel consumption rate as the amount of combustion gas decreases.

? Among the exhaust gas introduction passages, the exhaust system 16 of this dryer itself
The introduction passage 216 connected to the smelter operates at its maximum when the amount of exhaust gas from the exhaust gas generation sources 50, 52, 54 at various locations in the smelter decreases, and directs the exhaust gas to be discharged from the exhaust system 16 to the flash drying pipe. Return on 12th.

Conduit 48 draws in air when the amount of exhaust gas from each exhaust gas source 50, 52, 54 is further reduced.

The inner wall of the combustion chamber 30 is shaped according to the combustion situation (, passage 3
It is cooled by air or gas introduced from 4.

This air is introduced from one side of the passage 340 that is open to the atmosphere, and the gas is introduced from the exhaust port of the purple air heater 52 via the branch circuit 35.To cool the combustion chamber 30, t Whether to use air as a main source or to use an exhaust gun as a main source is selected depending on the overheating situation within the combustion chamber 30.

The drying and carrier medium gas, which is generated by mixing the combustion gas, each exhaust gas, and cooling gas as necessary, and which is controlled within a predetermined temperature range, is sent to the cage 20 and supplied from the ore feed port 24. Disperse the powder ore and use the flash drying tube 12
flowing within.

The gas in which the fine ore is dispersed is conveyed toward the cyclone 14 by the suction force of the blower 18, and the fine ore is dried in the process of being conveyed through the airflow inside the airflow drying tube 12.

The mixed air flow that has reached the cyclone 14 is separated into fine ore and hygroscopic gas, and the separated fine ore is recovered from the lower part of the cyclone 14.

Hygroscopic gas! The air is exhausted from the upper part of the cyclone 14 to the exhaust system 16 via the blower 18.

This exhaust system 16 is equipped with a dust collector 28 having a dust removal function or other duct-containing exhaust gas purification device and a dust remover in series, so that all exhaust gases are rendered harmless and released into the atmosphere.

If necessary, a part of the exhaust gas that has reached the exhaust system 16 is sent to the outlet side of the combustion chamber 30 through the introduction passage 46 and used again as a drying medium.

Each exhaust gas generation source 5 in the smelter listed in the above equipment
The exhaust gases generated from each of Nos. 4, 52, 50, and 16 have the following conditions according to the implementation sequence.

(1) Amount of exhaust gas discharged from the refining furnace 54 Gas temperature dust content H20 Heat retention 12000Nr 1250°C 0.3 f~3~
5 Smelting at the time of steaming 12000Nt 4(1)℃ 5～201 2
~ 10 o'clock ~ Ta (2)
Amount of exhaust gas discharged from the steam heater 52 Gas temperature Dust content H2013500 Nm/h300
°C 0.1 mowing. 15 6-7%? /Nrrl (3) "Amount of exhaust gas generated from the environmental local gas generation section 50 Gas temperature Dust content H2010000N
I'm 30℃ O~2t~1~2 Excellent (4) Amount of exhaust gas discharged from the exhaust system 16 of the dryer itself Gas temperature 7 0 0 0 0 Nm3/h 7 0
℃ As a result of utilizing each of the exhaust gases under the above conditions as part of the drying medium gas by the method of the present invention, compared to the case where the entire amount of the drying medium gas was generated only by mixing the combustion gas of the hot air stove and air, The effect of reducing heavy oil consumption in the hot air stove as shown in Table 2 below was obtained.

Example 3 in Table 2 is the result of reducing the cross-sectional area of the flash drying tube by more than about 70 points compared to the other examples.

As is clear from the above embodiments, when the embodiments of the present invention are used, heavy oil consumption is greatly reduced compared to when the entire amount of drying medium gas is generated by mixing only combustion gas and air. ing.

Although no numerical values are entered, the exhaust system of the dry air machine
If the exhaust gas discharged from the drying medium is returned to the drying medium gas and reused, the temperature of the exhaust gas is quite high (approximately 70°C).

), heavy oil consumption can be further reduced.

Furthermore, according to the present invention, the dust-containing exhaust gas generated at various locations in the smelter is utilized as a drying medium gas for flash drying, so that various dusts, CO2, H20, CO,
Harmful components including SO2 etc. are purified by an exhaust gas purification device in the drying equipment.

Therefore, the problem of processing the duct-containing exhaust gas generated in the smelter is solved, and there is an advantage that the equipment for purifying the dust-containing exhaust gas can be reduced.

[Brief explanation of the drawing]

FIG. 1 is an overall system diagram showing a specific array of devices for carrying out the present invention, and FIG. 2 is a cross-sectional structural diagram of the drying medium gas generating device. 10...Hot stove, 12...Airflow drying tube, 14...Cyclone, 16...Exhaust system, 18...Blower, 20
... Cage mill, 30... Combustion chamber, 34... Cooling air and gas supply passage, 40... First dust-containing exhaust gas introduction passage, 42... Second dust-containing exhaust gas introduction passage. Introduction passage, 44... third dust-containing exhaust gas introduction passage,
46... Fourth exhaust gas introduction passage, 48... Air introduction pipe, 41, 43, 45, 47, 49... Damper,
50...Environmental local gas generation unit, 52...Steam heating device, 54...Smelting furnace.

Claims (1)

[Claims] 1. When transporting powdered ore containing moisture using an airflow medium, the combustion gas from the burner and the dust-containing exhaust gas produced as a by-product in the smelter are mixed with an air volume sufficient to transport the powdered ore. 1. A method for flash drying fine ore, characterized in that the mixed gas is mixed so as to obtain a temperature sufficient for drying the powder ore, and the mixed gas is used as the gas flow medium.