JP2019120473A - Fluidization roasting furnace - Google Patents

Abstract

To provide a fluidization roasting furnace capable of improving quality and the rate of collection after roasting even with respect to objects to be roasted that cause gas due to roasting.SOLUTION: A fluidization roasting furnace 10 is provided with a cylindrical furnace core 11 where objects to be roasted are roasted by using gas flowing from downstream to upstream. The cylindrical furnace core 11 has a plurality of inner surface vertical parts 17 different in in-furnace cross-sectional area in a region in a height direction where a fluidized layer in which the objects to be roasted are roasted is formed. The in-furnace cross-sectional area of the inner surface vertical part 17 positioned above is larger than the in-furnace cross-sectional area of the inner surface vertical part 17 positioned below. In this construction, even when gas is generated by roasting the objects to be roasted, a volume increase of the generated gas is absorbed by the inner surface vertical part 17 above, so that speed of fluidized gas is maintained evenly in the fluidized layer. Thus, quality of the objects to be roasted after roasting and the rate of collection are improved.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fluid roaster. More particularly, the present invention relates to a fluidized roaster capable of roasting a roasted toast that requires high quality.

  In general, a fluidized roasting furnace creates a mixed state with a medium by floating granular material to be roasted as if it were a fluid, while supplying a gas using a raw material alone or a fluidized medium, It is a device that roasts By performing roasting in a state in which the raw material to be roasted and the fluid medium are mixed, the roasting proceeds while the raw material and the fluid medium collide, and the raw material can be retained in the fluid bed for a relatively long time, It can be roasted efficiently.

  In order to ensure the roasting of the raw material supplied using such a flow roasting furnace, the flow rate of the gas flows with the raw material (hereinafter, may be referred to as "the to-be-baked material" in the present specification) The superficial velocity of the mixture with the medium must be precisely controlled to be in the range above the minimum fluidization velocity and below the terminal velocity.

  Here, the "empty velocity" is an actual velocity obtained by gas flow rate / cross-sectional area in the furnace. Here, "in-furnace cross-sectional area" refers to the area in the furnace in a plane perpendicular to the axis of the furnace core. Also, the "minimum fluidization velocity" is the minimum velocity at which the powder (the mixture of the roasted product and the fluid medium) starts to flow. The term "end velocity" refers to the velocity at which powder begins to rise and pop out of the fluid bed.

  As described above, the speed control needs to be performed accurately for the following reasons. That is, if the flow velocity of the supplied gas is less than the "minimum fluidization velocity" of the mixture of the raw material and the fluid medium, the raw material is not fluidized and roasting does not proceed uniformly, so that aggregation of the raw material occurs Problems arise.

  On the other hand, if the flow rate of the gas is equal to or higher than the “end velocity” of the mixture, the flow rate is too fast and the raw material or the fluid medium is made to flow together with the gas. There is a problem that the recovery rate is greatly reduced.

  That is, in the fluid roasting, it is necessary to control the gas flow rate within an appropriate range to fluidize the raw material in the fluid bed for a time sufficient for roasting.

  Patent Literatures 1 and 2 disclose the configuration of the above-described fluidized roasting furnace. These fluidized roasters have several problems in order to produce them industrially. The four listed below are considered to be important among them.

  The first problem is that continuous processing is difficult. From the viewpoint of efficiency, raw materials are continuously fed in continuous processing. Under the present circumstances, if the raw material in roasting and the raw material which is not roasted mix, and it is not possible to carry out roasting efficiently, it will be that the quality of a roasting thing fell and it is unpreferable.

  In order to solve the above problems, it is conceivable to separate the raw material inlet and the raw material recovery port so that the raw material travels from the inlet to the recovery port, but in the case of fluidized roasting, the granular raw material is Since it fluidizes like a fluid, the raw material which has not been roasted immediately after charging and the raw material which floats in the furnace for a while and which has been roasted immediately mixes with it, and only the raw material which has been roasted is recovered It is impossible to do this, and raw materials that are not sufficient for roasting are recovered in a mixed state. For this reason, a thing low in quality will be collect | recovered, and a roasting efficiency will also worsen.

  According to Patent Document 1, old sand dust is supplied into the roasting chamber of the fluidized roasting furnace, placed in the roasting chamber, fluidized roasted, and overflowed at the upper position of the fluidized bed formed in the roasting chamber. There is disclosed a technique of overflowing from a flow port and recovering as recycled dust. Here, the old sand dust is obtained by collecting the dust generated by the pipe type dry regenerator for regenerating cast old sand. In addition, silica sand is accommodated as the base sand at the bottom of the fluidized roasting furnace.

  In addition, it is also disclosed that compressed air is blown toward the outlet of the chute from a nozzle formed at the tip of the compressed air blowing pipe provided at the inlet of the chute. That is, the old sand dust is supplied into the furnace while blowing compressed air toward the chute, and the old sand dust is overflowed and collected from the overflow port.

  In the fluidized-bed roaster disclosed in Patent Document 1, the old sand dust is fluidized since the old sand dust supply height position is almost the same as the height position of the overflow (recovery port). For sure, only those that have been roasted can not overflow and be recovered from the overflow.

  That is, since old sand dust before roasting is supplied one after another into old sand dust being fluidized and roasted, old sand dust collected from the overflow port is old that roasting is insufficient Sand dust is mixed. Therefore, continuous processing is difficult at this point.

  With respect to the first problem described above, it is necessary to slow the supply speed of old sand dust as much as possible in order to recover old sand dust that has been roasted as much as possible by the method disclosed in Patent Document 1 Conceivable. However, in this case, the treatment with the fluidized roasting furnace becomes very inefficient, and again, continuous treatment is difficult.

  The second problem is that it is difficult to separate the gas used for roasting after roasting and the roasted material after roasting.

  In Patent Document 2, a step of oxidizing and roasting a metal iron source in a fluidized roasting furnace, a step of peeling off an oxide layer of coarse particles discharged from an overflow port of the roasting furnace, and iron oxide after the peeling step A process for producing high-grade iron oxide is disclosed, which comprises the steps of: circulating the metal iron powder in a fluidized roasting furnace, and flowing out the produced finely powdered iron oxide together with the roasting gas to capture and recover from the roasting gas. ing.

  However, although it is described in Patent Document 2 that the finely powdered iron oxide is made to flow out with the torrefaction gas and captured and recovered from the torrefaction gas, specifically how to flow out the finely divided iron oxide with the torrefaction gas Is not clearly shown. That is, how to separate finely powdered iron oxide and roasting gas efficiently and to capture and recover finely powdered iron oxide is completely unknown.

  Further, Patent Document 2 also discloses that the exfoliated oxide film is caused to accompany the flowing roasting furnace exhaust gas and discharged out of the furnace, but it is accompanied by the flowing roasting furnace exhaust gas by any method and it is disclosed outside the furnace It is also unclear as to whether it will be discharged.

The third problem is that the product purity and the like required for the roasted material to be roasted differ. The specific example of the raw material of a fluidized roasting furnace is mentioned and demonstrated. For example, nickel oxide (NiO), which is often used as a material of secondary batteries as its raw material, becomes a very hard-to-heat roasted product in terms of purity and the like. Nickel oxide is produced by adding an alkali to an aqueous solution containing nickel sulfate (NiSO ₄ ) to neutralize it to obtain nickel hydroxide (Ni (OH) ₂ ) and roasting the nickel hydroxide. .

  With respect to this nickel oxide, the sulfur grade of the impurities contained in the obtained nickel oxide is high, for example, when it exceeds 100 ppm, it is not preferable because the influence of lowering the characteristics of the battery manufactured from nickel oxide occurs. For this reason, it is essential to reduce sulfur by roasting uniformly and reliably while removing the sulfur adhering by pretreatments, such as washing. That is, in the configuration of the fluidized roasting furnace disclosed in Patent Document 1 etc., there is a problem that the uniformity of roasting can not be sufficiently improved for a predetermined raw material.

The fourth problem relates to the characteristics of the roasted material to be roasted. In the case of the above-mentioned fluid roasting of nickel hydroxide, it is also necessary to consider the influence of the generated gas. That is, at the same time as the nickel hydroxide is roasted to form nickel oxide, water (H ₂ O), that is, water vapor gas is also generated along with the decomposition of the nickel hydroxide. Due to the volume of the generated steam gas, the flow velocity in the fluidized roasting furnace is rapidly increased, and as a result, the roasted material is discharged as it is with incomplete roasting, causing a problem that the quality and the recovery rate decrease.

  The influence of the gas generated with the above-described roasting also occurs, for example, when roasting copper concentrate to separate arsenic, other than in the case of nickel hydroxide and the like. That is, when copper concentrate is roasted in an inert gas, arsenic sulfide is formed as a gas, and copper concentrate is flushed out of the furnace.

  With respect to the fourth problem, in the case where gas is generated by roasting, in order to prevent the discharge of the unreacted raw material from the fluidized roasting furnace, the amount of gas to be generated is predicted in advance, and It is necessary to reduce the amount of gas delivered to a corresponding amount of fluidization. However, the above-mentioned steam gas and the like are generated along with the sinter reaction in the fluidized bed, and if the gas supply amount for fluidization is uniformly reduced, the fluidization does not occur and the reaction does not proceed, or the excess does not occur. It becomes a flow rate, and the subject that the target roasting does not advance smoothly arises.

  With respect to the fourth problem, in Patent Document 1, a gas with an expanded cross-sectional area is provided on the outlet side of the core body of the fluidized-bed firing furnace, and the gas flowing in the furnace of the fluidized-bed roasting furnace Also, the flow velocity of the to-be-baked product is reduced by the spread of the cross-sectional area to prevent the discharge of the insufficiently roasted raw material.

JP 2000-42515 A Japanese Patent Application Laid-Open No. 61-236616

  With respect to the above third and fourth problems, when a portion with an enlarged cross section in the furnace is installed on the outlet side of the core body of the fluidized bed calciner described in Patent Document 1, that is, fluidized roasting is performed. When a portion where the cross-sectional area in the furnace is enlarged is installed in the part above the existing fluidized bed, the cross-sectional area in the furnace does not change up and down in the part where the fluidized bed is being formed Because of the straight cylinder shape, the generated gas tends to make the velocity of the fluidizing gas nonuniform within the fluidized bed, and therefore, the to-be-baked product is often not fully burned but directed toward the outlet side of the core body. There is a problem that the quality and recovery rate decrease.

  An object of the present invention is to provide a fluidized roasting furnace capable of enhancing the quality and recovery rate after roasting even if the roasted product generates gas due to roasting, in view of the above circumstances.

The fluidized-bed roasting furnace according to the first aspect of the present invention is provided with a cylindrical core portion in which a roasted material is roasted using gas flowing from the lower side to the upper side, and the cylindrical core portion In the region in the height direction in which the fluidized bed to be roasted is formed, the cross-sectional area of the inner vertical portion of the inner vertical portion located on the upper side has a lower side It is characterized by being larger than the cross-sectional area in the furnace of the above-mentioned inner surface perpendicular part located in.
A second aspect of the present invention is characterized in that, in the first aspect, the tubular core portion has three or more of the inner surface vertical portions.
In the flow roasting furnace according to the third aspect of the present invention, in the first aspect or the second aspect of the present invention, the cross section in the furnace of the inner surface vertical portion located above the inner surface vertical portion located in the lowermost position is located in the lowest position. It is characterized by being 1.5 times or more and 5 times or less the cross-sectional area in a furnace of the above-mentioned inner surface perpendicular part.
In the fluidized roasting furnace according to the fourth aspect of the present invention, in any one of the first aspect to the third aspect of the present invention, the setting of the roasting temperature of two of the inner surface vertical portions among the plurality of inner surface vertical portions having different furnace cross-sectional areas It is characterized by being different.

According to the first aspect of the present invention, the cylindrical core portion forming the fluidized-bed roasting furnace has a plurality of inner surface vertical parts different in cross-sectional area in the furnace in the region in the height direction where the fluidized bed is formed Since the cross-sectional area in the furnace is larger than that on the lower side, the volume increase of the generated gas is absorbed by the inner surface vertical part on the upper side even when the gas is generated due to the roasting of the to-be-baked product. The velocity of the fluidizing gas is maintained uniform. This improves the quality and recovery of the roasted product after roasting.
According to the second aspect of the present invention, since the cylindrical core portion has three or more inner surface vertical portions, the cross-sectional area in the reactor can be increased stepwise from the bottom to the top, so that the fluid flow inside the fluidized bed The gas velocity is maintained more uniformly.
According to the third invention, the in-furnace cross-sectional area of the upper inner surface vertical portion is 1.5 to 5 times the in-furnace cross-sectional area of the lowermost inner surface vertical portion, so that the gas flow rate such as water vapor is large Even if the flow rate is increased, the velocity of the fluidizing gas can be maintained uniformly in the fluidized bed.
According to the fourth aspect of the present invention, by setting the roasting temperatures of the two inner surface vertical parts differently, the roasting can be progressed stepwise, and the velocity of the fluidizing gas can be maintained more uniformly inside the fluidized bed. Ru.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing from the front direction of the fluidized-bed roasting furnace which concerns on 1st Embodiment of this invention. It is sectional drawing from the front direction of the fluidized-bed roasting furnace which concerns on 2nd Embodiment of this invention.

  Next, an embodiment of the present invention will be described based on the drawings. However, the embodiments shown below exemplify a fluidized roasting furnace for embodying the technical idea of the present invention and an operating method thereof, and the present invention relates to a fluidized roasting furnace and an operating method thereof as follows. Not specific to Note that the size or positional relationship of members shown in each drawing may be exaggerated for the sake of clarity.

First Embodiment
FIG. 1 shows a cross-sectional view from the front direction of the fluidized-bed roasting furnace 10 according to the first embodiment of the present invention. In FIG. 1, black thick arrows indicate the flow direction of the fluidizing gas. A cylindrical core portion 11 is provided in the flow roasting furnace 10 of the present embodiment in a state where the axis is vertical. A fixed bed 15 is provided below the cylindrical core portion 11. The fixed layer 15 may be, for example, one filled with a spherical ceramic such as alumina, and the ceramic may be porous and may have a high filling rate. Then, the fixed layer 15 may be composed of several layers so that the roasted object does not fall below the fixed layer 15. For example, spherical alumina may be used below the fixed layer 15 and smaller spherical alumina may be used above the fixed layer 15. A flow gas introduction pipe 12 for introducing flow gas from the lower portion of the cylindrical core portion 11 is provided on the lower surface of the fixed layer 15. Since the fluidizing gas is supplied from the fluidizing gas inlet pipe 12 in the direction indicated by the thick arrow, the fluidizing medium 31 and the raw material 32 located on the fixed bed 15 are fluidized to form a fluidizing bed. The roasting is carried out with the raw material 32 suspended in the fluidized bed.

  At the lower part of the cylindrical core portion 11, a heater 13 for holding the flowing medium 31 or the like at a constant temperature is provided. The heater 13 may not be provided depending on the raw material 32. In the case where the heater 13 is not used, for example, a high temperature fluidizing gas may be flowed to carry out the flow roasting.

  The raw material 32 to be supplied to the cylindrical core portion 11 is appropriately charged by the raw material charge pipe 14 provided on the side of the cylindrical core portion 11. Then, the raw material feeding pipe 14 is closed by a lid or a valve after the raw material feeding.

  The cylindrical core portion 11 of the fluidized bed roasting furnace 10 of the present embodiment has a plurality of inner surface vertical portions 17 having different cross-sectional areas in the reactor. In the present embodiment, the cross section of the inner surface vertical portion 17 is circular. The cylindrical core portion 11 is formed by connecting and integrating the inner surface vertical portions 17 with each other by the enlarged portions 16. In the present embodiment, two inner surface vertical parts 17 are provided, and the cross-sectional area in the furnace of the inner surface vertical part 17b located on the upper side is larger than the cross-sectional area in the furnace of the inner surface vertical part 17a located on the lower side There is. The fluidized bed in which the to-be-baked product is roasted is formed across the two inner surface vertical parts 17. That is, in the present embodiment, the fluidized bed is formed over part of the area in the height direction of the lower inner surface vertical part 17 and part of the area in the height direction of the upper inner surface vertical part 17 . However, the fluidized bed may be formed over the entire height direction of any one of the inner surface vertical parts 17. In the present specification, when all of the inner surface vertical parts are meant, reference numeral 17 is used, and when the inner surface vertical parts having different cross-sectional areas are meant, reference numerals 17a and 17b are used.

  The cylindrical core portion 11 forming the fluidized bed roasting furnace 10 has a plurality of inner surface vertical parts 17 having different sectional areas in the furnace in a region in the height direction where the fluidized bed is formed, and the upper side is more than the lower side Since the cross-sectional area in the furnace is large, even when gas is generated by roasting of the to-be-baked object, the volume increase of the generated gas is absorbed by the upper surface vertical portion on the upper side. The speed is maintained uniformly. This improves the quality and recovery of the roasted product after roasting.

  The cross-sectional area in the furnace of the upper inner surface vertical portion 17b is in the range of about 1.2 to 10 times the cross-sectional area in the furnace of the lower inner surface vertical portion 17a which is the lowermost stage. The cross-sectional area in the furnace of the upper inner surface vertical portion 17b is 1.5 times to 5 times the cross-sectional area of the lower inner surface vertical portion 17a at the point of continuing the stable flow roasting. It is preferable to set the cross-sectional area of If the cross-sectional area in the furnace is less than 1.2 times, the change in flow velocity is small and it is difficult to maintain stability.

  In addition, although the enlarged part 16 which is a part which connects the part which the difference in cross-sectional area produces may be horizontal, as shown in FIG. 1, it is a structure which provides an inclination so that it may go down toward the furnace core side and connects. Is preferred. With such a structure, it is possible to prevent the occurrence of a blank portion where there is no flow of the flow gas, and it is possible to prevent the to-be-baked product from being deposited on the enlarged portion 16.

  In addition, a device for generating vibrations such as a knocker, a vibrator, or an ultrasonic transducer is provided outside the furnace of the enlarged portion 16 or a device for blowing gas from the outside is provided. It is also possible to provide a mechanism that can be paid off.

In nickel hydroxide (Ni (OH) ₂ ), the properties of the to-be-baked product change greatly depending on the to-be-baked temperature, or gases having different properties are generated. In the case of such a raw material, if the roasting temperature is located in one temperature zone, gas will be generated at a stretch, or the properties of the roasted product will change at a stretch, and uniform flow can not be achieved. Then, the to-be-fired roasted product may be brought out in a state where the roasting is incomplete due to the generated gas.

  Specifically, in nickel hydroxide, the contained water first evaporates at 100 ° C., then the hydroxyl group (OH group) is decomposed at about 300 ° C. to generate steam, and the contained sulfur starts to fly at about 700 ° C. .

  In the flow roasting furnace 10 of the present embodiment, the cylindrical core portion 11 of the flow roasting furnace 10 is configured to have a plurality of inner surface vertical portions 17, and then the temperature is changed for each inner surface vertical portion 17 You can also bake it.

  For example, by providing the heater 13 for each of the inner surface vertical parts 17, it is possible to control to different temperatures. The heater 13 is preferably an electric type. It is because it is possible to control with high accuracy if it is an electrical type. Moreover, it is preferable to make the installation density of the heater 13 different in the upper and lower sides in the inner surface vertical part 17. In this case, the temperature change can be gently generated in the vertical direction.

  By setting the roasting temperatures of the two inner vertical portions 17 differently, the roasting can be progressed in stages, and the velocity of the fluidizing gas can be maintained more uniformly inside the fluidized bed. Therefore, it is possible to suppress the popping out of the to-be-baked material due to the fluctuation of the gas generation and the like, and as a result, it is possible to obtain the to-be-heated product of high quality with high recovery rate.

(Operation method of fluidized bed roasting furnace 10 according to the first embodiment)
As shown in FIG. 1, a fluidized bed baking furnace 10 is charged with a fluidized medium 31 for producing a fluidized bed together with a raw material 32. The fluidizing gas is introduced from the fluidizing gas introduction pipe 12 into the fluidizing and burning furnace 10, and the raw material 32 is charged in a predetermined amount. The flow velocity of the fluidizing gas is adjusted so that the "spatial velocity" of the mixture of the feedstock 32 and the fluid medium 31 is greater than or equal to the "minimum fluidization velocity" and less than the "end velocity".

  It is preferable that the fluidized roasting furnace 10 be heated by the heater 13, and the raw material 32 be charged and roasted. It is because it will take time and heating efficiency if it heats after raw material injection | throwing-in. It is preferable that the heater 13 be an electric type in terms of easy control. Although not shown, a gas burner or the like is preferable because it is inexpensive and inexpensive.

Second Embodiment
FIG. 2 shows a cross-sectional view from the front direction of the fluidized-bed roasting furnace 10 according to the second embodiment. The difference from the flow roasting furnace 10 of the first embodiment is that the cylindrical core portion 11 has three inner vertical portions 17. In the present embodiment, the number of the inner surface vertical parts 17 is three, but there is no problem if there are four or more.

  In the present embodiment, the cross section of the inner surface vertical portion 17 is circular. The cylindrical core portion 11 is formed by connecting and integrating the three inner surface vertical portions 17 with each other by two enlarged portions 16 existing therebetween. In the present embodiment, the cross-sectional area in the furnace of the two inner surface vertical parts 17b and 17c located on the upper side is larger than the cross-sectional area in the furnace of the inner surface vertical part 17a located on the lowermost stage. In addition, the cross-sectional area in the furnace of the inner surface vertical portion 17c located in the uppermost stage is larger than the cross-sectional area in the furnace of the inner surface vertical portion 17b located in the middle step. The fluidized bed in which the to-be-baked product is roasted is formed across the three inner surface vertical portions 17. That is, in the present embodiment, the fluidized bed is formed from part of the area in the height direction of the lowermost inner surface vertical part 17a to part of the area in the height direction of the uppermost inner surface vertical part 17c. . However, the fluidized bed may be formed over the entire area in the height direction of the uppermost or lowermost inner surface vertical portion 17.

  The cross-sectional area in the furnace of the inner surface vertical parts 17b and 17c located above the lowermost stage is in the range of about 1.2 to 10 times the cross-sectional area in the furnace of the lower surface inner vertical part 17a. Further, the cross-sectional area in the furnace of the inner surface vertical parts 17b and 17c located above the lowermost stage is 1 of the cross-sectional area in the furnace of the lower inner surface vertical part 17a at the point of continuing the stable flow roasting. Preferably, the cross-sectional area is not less than 5 times and not more than 5 times. If the cross-sectional area in the furnace is less than 1.2 times, the change in flow velocity is small and it is difficult to maintain stability.

  Since the cylindrical core portion 11 has three or more inner surface vertical portions 17, the cross-sectional area in the reactor can be gradually increased from the bottom to the top, so the velocity of the fluidizing gas in the fluidized bed can be increased. It is maintained more uniformly. In addition, the operating method of the flow | style-burning furnace 10 is the same as 1st Embodiment.

  Hereinafter, experiments related to the present invention will be performed, and examples of each embodiment of the present invention will be shown and described. The present invention is not limited to the following examples.

(Experiment 1) (Verification of plural inner surface vertical parts, raw material: nickel hydroxide)
<Raw material>
Nickel hydroxide (Ni (OH) ₂ ) was prepared as a raw material to be roasted (to be roasted) 32. The nickel hydroxide had an average particle diameter of 22.3 to 24.3 μm, and was subjected to vacuum heat treatment at 175 ° C. for 3 hours in vacuum beforehand to substantially remove the contained water. It was analyzed that sulfur was contained in a proportion of 2.1 to 2.3% by weight. The other impurity components were substantially negligible.

  In each of the following experiments, batch processing was performed. That is, a predetermined amount of each raw material 32 is charged into the fluidized roasting furnace 10, and then air is sent from the lower part of the furnace as a fluidized gas to be fluidized and heated to a predetermined temperature and maintained to be fluidized roasting It was done, and it was made for the flow gas after roasting to be discharged from the upper part.

<Flow roasting process>
In Experiment 1, the flow roasting furnace 10 according to the first embodiment shown in FIG. 1, the flow roasting furnace 10 according to the second embodiment shown in FIG. A furnace was used. The raw material nickel hydroxide was roasted by these roasting furnaces, and the roasted product nickel oxide (NiO) was recovered.

  Specifically, in the fluidized-bed roasting furnace 10 of the first embodiment, the ratio of the cross-sectional area in the upper furnace to the cross-sectional area in the lowermost stage was changed as shown in Table 1 and used. In the second embodiment, the ratio of the cross-sectional area of the middle stage to the cross-sectional area of the lowermost stage is 1.6, and the cross-sectional area of the uppermost stage to the cross-sectional area of the lowermost stage. The ratio of H was changed as shown in Table 1 and used. Examples 1 to 5 which were roasted in the flow roasting furnace 10 of the first embodiment and examples 6 to 10 which were roasted in the flow roasting furnace of the second embodiment The sample roasted in a furnace is Comparative Example 1.

  In the table, the lowermost inner surface vertical portion 17a is the first step, the inner surface vertical portion 17b located on the upper side next to the first surface inner surface vertical portion 17a is the second step, and the second surface is next to the inner surface vertical portion 17b The inner surface vertical part 17c located in the upper side was displayed as 3rd step | stage.

  The weights of the input materials were all the same, and the roasting conditions were all the same. Specifically, the roasting temperature was 900 ° C., the roasting time was 20 minutes, and air was used as the fluidizing gas. After the predetermined roasting, the furnace was cooled and the roasted material in the furnace was recovered.

<Evaluation>
In each of the treatments of Examples 1 to 10 and Comparative Example 1, the recovery rate (that is, the actual yield) of the sample obtained by roasting, the content of nickel oxide in the recovered sample, and sulfur in the recovered sample Content was evaluated. Table 1 shows the measurement results. The evaluation method is as follows.

[Recovery rate of sample obtained by roasting]
The recovery rate of the sample obtained by roasting was calculated by the following equation 1.

[Equation 1]
R = W ₁ / (W ₂ −S) × 100

R: Recovery rate [%]
W ₁ : Weight of collected sample W ₂ : Weight S of the loaded raw material 32 (this time Ni (OH) ₂ ) was completely roasted (this time NiO) S: Sulfur contained in the loaded raw material 32 Weight of

[Proportion of the content of nickel oxide in the collected sample]
The ratio of the content of nickel oxide in the collected sample is calculated by calculating the content of nickel oxide (NiO) and nickel hydroxide (Ni (OH) ₂ ) contained in the collected sample, respectively. It calculated as a ratio (weight%) of NiO content to a total value.

[Sulfur content in the collected sample]
The content of sulfur in the recovered sample was measured using a sulfur analyzer (manufactured by Mitsubishi Chemical Corporation, model: TOX-100).

  As shown in Table 1, Examples 1 to 10 using the fluidized-bed roasting furnace 10 of the first embodiment or the second embodiment gave good results. That is, the recovery rates (actual yields) all show high values of 99% or more, and the content of nickel oxide in the recovered products was all roasted to NiO at 99% or more. Moreover, the sulfur grade in the collection | recovery thing which is mostly nickel oxide was also low, and high quality nickel oxide was able to be obtained.

  On the other hand, in Comparative Example 1 in which the straight-tube roasting furnace was used, the recovery rate was lower and the sulfur grade in the recovered material was also higher than in the example.

(Experiment 2) (Verification of multiple inner surface vertical parts, raw material: copper concentrate)
<Raw material>
Arsenic and sulfur grade copper concentrates shown in Table 2 were used as raw materials (to be baked) 32 to be roasted.

<Flow roasting process>
In Experiment 2, as in Experiment 1, the flow roasting furnace 10 according to the first embodiment shown in FIG. 1, the flow roasting furnace 10 according to the second embodiment shown in FIG. , A straight-tube smoldering furnace was used. Raw material copper concentrate was roasted by these roasting furnaces.

  Specifically, in the fluidized-bed roasting furnace 10 of the first embodiment, the ratio of the cross-sectional area in the upper furnace to the cross-sectional area in the lowermost stage was changed as shown in Table 3 and used. In the second embodiment, the ratio of the cross-sectional area of the middle stage to the cross-sectional area of the lowermost stage is 1.6, and the cross-sectional area of the uppermost stage to the cross-sectional area of the lowermost stage. The ratio of H was changed as shown in Table 3 and used. Examples 11 to 15 were roasted in the flow roasting furnace 10 of the first embodiment, Examples 16 to 20 were roasted in the flow roasting furnace of the second embodiment, a stepless roasting The sample roasted in a furnace is Comparative Example 2. The notation of the inner surface vertical portion 17 in the table is the same as in Experiment 1.

  The weights of the input materials were all the same, and the roasting conditions were all the same. Specifically, the roasting temperature was 900 ° C., the roasting time was 4.0 hours, and nitrogen was used as the fluidizing gas. After the predetermined roasting, the furnace was cooled and the roasted material in the furnace was recovered.

<Evaluation>
In each of the treatments of Examples 11 to 20 and Comparative Example 2, the recovery rate (scattering rate) of the sample on the filter and the arsenic content in the copper concentrate were evaluated by the following methods. Table 3 shows the measurement results. The evaluation method is as follows.

[Recovery rate of sample on filter]
After roasting, the sample flushed with the exhaust gas was collected by a bag filter, and the recovery rate (scattering rate) was calculated by the following equation from the recovered amount. In addition, it is a loss that the copper concentrate is originally collected by the filter, which is not preferable, and the recovery rate (scattering rate) is preferably low.

[Equation 2]
R ₂ = W ₃ / W ₄ × 100

R ₂ : Recovery rate with filter [%]
W ₃ : Weight of collected sample W ₄ : Weight of input material (in this case, copper concentrate)

[Arsenic content of sample before and after experiment]
The samples before and after the experiment were analyzed for arsenic and sulfur using an ICP emission spectrometer.

  As shown in Table 3, good results were obtained in Examples 11 to 20 using the fluidized-bed roasting furnace 10 of the first embodiment or the second embodiment. That is, in the examples, the content of arsenic was less than 0.1% by weight, and the content of arsenic and sulfur in the concentrate was greatly reduced. As arsenic and sulfur in the copper concentrate decreased, the copper content in the copper concentrate was increased by 10% or more by fluid roasting, and copper could be concentrated.

  On the other hand, Comparative Example 2 in which the straight-tube smoldering furnace was used resulted in an undesirable result. That is, the arsenic grade was 0.2% by weight, and the loss with the filter was significantly increased to 10% or more.

(Experiment 3) (Verification of multiple roasting temperature settings, raw material: nickel hydroxide)
<Raw material>
Nickel hydroxide (Ni (OH) ₂ ) was prepared as a raw material to be roasted (to be roasted) 32. Nickel hydroxide had an average particle diameter of 22.5 to 24.5 μm, and was subjected to vacuum heat treatment under vacuum at 175 ° C. for 3 hours in advance to substantially remove the contained water. When analyzed, the sulfur grade of nickel hydroxide was 2.0 to 2.2% by weight. Other impurity components were substantially negligible.

<Flow roasting process>
In Experiment 3, the fluidized-bed roasting furnace 10 according to the first embodiment shown in FIG. 1 was used. Raw material nickel hydroxide was roasted by this roasting furnace, and the roasted product nickel oxide (NiO) was recovered.

  Specifically, in the fluidized-bed roasting furnace 10 of the first embodiment, the ratio of the cross-sectional area in the upper furnace to the cross-sectional area in the lowermost stage was changed as shown in Table 4 and used. In Table 4, the lowermost inner surface vertical portion 17a is displayed as the first step, and the inner surface vertical portion 17b located on the upper side next to the first inner surface vertical portion 17a is displayed as the second step. In Examples 21 to 25, the roasting temperature at the first inner surface vertical portion 17a is 400 ° C., and the roasting temperature at the second inner surface vertical portion 17b is 900 ° C. In Examples 26 to 30, the roasting temperatures at the first and second internal vertical portions 17a and 17b are both 900.degree.

  The weights of the input materials were all the same, and the roasting conditions other than the roasting temperature were all the same. Specifically, the roasting time was 20 minutes, and air was used as the fluidizing gas. After the predetermined roasting, the furnace was cooled and the roasted material in the furnace was recovered.

<Evaluation>
In each of the treatments of Examples 21 to 30, the recovery rate of the sample obtained by roasting (ie, the actual yield), the content of nickel oxide in the recovered sample, and the content of sulfur in the recovered sample It was evaluated. Table 4 shows the measurement results. The evaluation method is the same as in Experiment 1.

  As shown in Table 4, Examples 21 to 25 in which the first-stage roasting temperature was lowered gave good results as compared with Examples 26 to 30 in which the same roasting temperature was used. That is, in Examples 21 to 25, when compared in Examples having the same cross-sectional area ratio, the recovery rates all showed high values, and the content ratio of nickel oxide in the recovered products also showed high rates. Further, when compared at the same sectional area ratio, Examples 21 to 25 showed lower values for sulfur grade.

(Experiment 4) (Verification of multiple roasting temperature settings, raw material: copper concentrate)
<Raw material>
The copper concentrate having the composition shown in Table 2 of Experiment 2 above was used as the raw material (the to-be-baked product) 32 to be roasted.

<Flow roasting process>
In Experiment 4, the fluidized-bed roasting furnace 10 according to the first embodiment shown in FIG. 1 was used. Raw material copper concentrate was roasted by this roasting furnace.

  Specifically, in the fluidized-bed roasting furnace 10 of the first embodiment, the ratio of the cross-sectional area in the upper furnace to the cross-sectional area in the lowermost stage was changed as shown in Table 5 and used. In Table 5, the lowermost inner surface vertical portion 17a is displayed as the first step, and the inner surface vertical portion 17b located on the upper side next to the first inner surface vertical portion 17a is displayed as the second step. In Examples 31 to 35, the roasting temperature at the first inner surface vertical portion 17a is 200 ° C., and the roasting temperature at the second inner surface vertical portion 17b is 900 ° C. In Examples 36 to 40, the roasting temperatures at the first and second internal vertical portions 17a and 17b are both 900.degree.

  The weights of the input materials were all the same, and the roasting conditions other than the roasting temperature were all the same. Specifically, the roasting time was 4.0 hours, and nitrogen was used as the fluidizing gas. After the completion of roasting, the furnace was cooled and samples in the furnace were collected.

<Evaluation>
In each of the treatments of Examples 31 to 40, the recovery rate (scattering rate) of the sample collected by the filter and the arsenic content in the copper concentrate were evaluated. Table 5 shows the measurement results. The evaluation method is the same as in Experiment 2.

  As shown in Table 5, Examples 31 to 36 in which the first-stage roasting temperature was lowered gave good results as compared with Examples 36 to 40 in which the same roasting temperature was used. That is, in Examples 31 to 35, when compared in Examples having the same cross-sectional area ratio, the recovery rate with the filter showed a low value.

10 flow roasting furnace 11 cylindrical core portion 17 inner vertical portion

Claims (4)

A cylindrical core portion is provided in which a to-be-fired roasted product is roasted using gas flowing from the lower side to the upper side,
The cylindrical core portion has a plurality of inner surface vertical portions having different in-furnace cross-sectional areas in a region in a height direction in which a fluidized bed in which the to-be-stokered material is roasted is formed,
The cross-sectional area in the furnace of the inner surface vertical portion located on the upper side is larger than the cross-sectional area in the furnace of the inner surface vertical portion located on the lower side
A fluid roasting furnace characterized by The cylindrical core portion has three or more of the inner surface vertical portions.
The fluidized-bed roasting furnace according to claim 1, characterized in that The cross-sectional area in the furnace of the inner surface vertical part located above the inner surface vertical part located in the lowermost stage is 1.5 to 5 times the cross-sectional area in the furnace of the inner surface vertical part located in the lowermost stage is there,
The fluidized-bed roasting furnace according to claim 1 or 2, characterized in that Among the plurality of inner surface vertical portions having different cross-sectional areas in the furnace, the setting of the roasting temperature of the two inner surface vertical portions is different,
The fluidized-bed roasting furnace according to any one of claims 1 to 3, characterized in that

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