JP6187233B2 - Autoclave curing method for cement bond agglomerate - Google Patents

Description

  The present invention relates to a curing method for achieving early strength development and reduction of water content of agglomerated ore when agglomerated fine ore using cement.

  Conventionally, a method of agglomerating fine ore by firing or sintering is known. On the other hand, a method of agglomerating fine ore using cement has been proposed (see Non-Patent Document 1, for example).

The method of agglomerating fine ore using cement is an environmentally preferable method because it is superior in energy saving and has no problem of exhaust gas as compared with the method of agglomerating by firing or sintering. However, the granulated product immediately after granulation is weak in strength, and it is generally employed that the primary curing is performed to a handleable strength (crushing strength of 3 N / mm ² or more) and then the secondary curing is performed. (For example, see Patent Documents 1 and 2).

  Therefore, although it is necessary to provide a primary curing yard adjacent to the granulation facility, the amount of processing is limited due to space restrictions of the primary curing yard. Therefore, it is desired to shorten the primary curing time.

  Also, if the granulated product gets wet in the rain before the primary curing is completed, the cement component in the granulated product will flow out in the rain and the granulated product will collapse, so it is necessary to construct a covered yard. Yes, equipment costs are high. Therefore, it is necessary to shorten the primary curing time.

  Further, after the primary curing, the granulated materials are agglomerated by the action of the cement, and when this is crushed, there is a problem such as dust generation. Therefore, it has been desired to develop a method for expressing the strength of cement bond agglomerates that does not depend on primary curing or secondary curing.

  Furthermore, in the curing at the yard, the strength is developed if time is taken, but the moisture of the agglomerated ore cannot be reduced and is brought into the blast furnace. The amount of agglomerate used was restricted from the viewpoint of the amount of water contained in the blast furnace.

  For this reason, development of the strength development method of the cement bond agglomerate which does not depend on the conventional primary curing and secondary curing, and also the curing method which enables low moisture content of the agglomerated mineral has been desired.

  FIG. 1 shows a conventional curing method using a primary yard and a secondary yard. Kneading and crushing is performed by a kneading and pulverizing machine 5 while adding additive water 4a for kneading to the raw materials cut out from the fine ore hopper 1, auxiliary raw material hopper 2 and cement hopper 3 respectively at a predetermined ratio, and then for granulation. It granulates with the dish type granulator 6a, adding the addition water 4b.

The granulated product is subjected to primary curing for 3 days in a primary curing yard 8 with a loader 9 designed to prevent dropping impact as much as possible after removing undersize and oversize with a sieve 7, and thereafter Secondary curing is performed in the secondary yard 10 for 10 days, and the strength is expressed up to the required strength in the blast furnace (crushing strength is 6 N / mm ² ), and the yard is used in the blast furnace.

  On the other hand, the autoclave treatment is a technique used for curing concrete and aging slag (see, for example, Patent Document 3 and Patent Document 4). For cold pellets using cement as a binder, the process is performed. There are many unclear points in conditions, handling methods, etc., and so far there have been few reports.

JP 51-025402 A JP 2005-200719 A JP 47-008602 A JP 2012-041234 A

Aiwa Takahashi, Reijiro Takahashi: Iron and Steel, 70 (1984), p37

  In view of the current state of the art, the present invention achieves early strength development of agglomerated ore (hereinafter referred to as “cement bond agglomerated ore”) in a method of agglomerating fine ore using cement. An object of the present invention is to provide an autoclave curing method that solves the problem by reducing the water content of the cement bond agglomerated mineral after the treatment.

  The present inventors diligently studied a method for solving the above problems. As a result, the following knowledge was obtained.

  Cement bond agglomerate can be moved up and down in the longitudinal direction of the carriage and placed on a transport / curing carriage with an opening on the bottom surface. After curing and then autoclave curing with saturated steam at 150 ° C or higher for 2 hours or more, early strength development of cement bond agglomerated minerals can be realized and moisture of cement bond agglomerated minerals after treatment can be reduced. Can be reduced.

  This invention was made | formed based on the said knowledge, and the summary is as follows.

(1) A curing method for cement bond agglomerates obtained by agglomerating fine ore with cement,
The (i) Cement the mass Naruko immediately after agglomerated with, the trolley for transport and curing with an opening on the lower surface, elevation freely by該台vehicle longitudinally movable stowage machine Leave still, pre-cured for 2 hours or more with natural ventilation, then
(Ii) In an autoclave, perform the main curing with saturated steam at 150 ° C. or more for 2 hours or more.
An autoclave curing method for cement bond agglomerated minerals.

  (2) The autoclave curing method for cement bond agglomerated minerals according to (1), wherein the precuring is performed for 4 hours or more.

  (3) The method for autoclaving a cement bond agglomerated mineral according to (1) or (2), wherein the main curing is performed for 4 hours or more.

  (4) The autoclave curing method for cement bond agglomerated minerals according to any one of (1) to (3), wherein saturated steam at 170 ° C. or higher is used as the saturated steam.

  According to the present invention, a cement bond agglomerated mineral having a high strength and a reduced water content can be obtained in a short time with a good yield.

It is a figure which shows the manufacturing method of the conventional cement bond agglomerate. It is a figure which shows an example of embodiment of the autoclave curing of a cement bond agglomerated mineral. It is a figure which shows the one aspect | mode of the loading machine for the loading of the cement bond agglomeration to the trolley | bogie for conveyance and curing in a loading field. It is a figure which shows another example of embodiment of the autoclave curing of a cement bond agglomerated mineral. It is a figure which shows another example of embodiment of the autoclave curing of a cement bond agglomerated mineral. It is a figure which shows a series of time charts from loading for every conveyance and curing cart to pre-curing, autoclave curing (main curing), and waiting for dispensing. The figure which shows the shape change of the agglomerate (granulated material) when changing the pre-curing time and the main curing time, and performing autoclave curing (main curing) with saturated steam at 150 ° C to determine the process conditions It is. The figure which shows the shape change of the agglomerate (granulated material) when changing the pre-curing time and the main curing time and performing autoclave curing (main curing) with a saturated steam at 170 ° C in order to determine the process conditions It is. It is a figure which shows the relationship between the main curing temperature when performing an autoclave curing, and the crushing strength of the agglomerated mineral after curing.

The cement bond agglomerated autoclave curing method of the present invention (hereinafter sometimes referred to as “the present invention curing method”) is a method for curing cement bond agglomerated minerals by agglomerating fine ore with cement. And
The (i) Cement the mass Naruko immediately after agglomerated with, the trolley for transport and curing with an opening on the lower surface, elevation freely by該台vehicle longitudinally movable stowage machine Leave still, pre-cured for 2 hours or more with natural ventilation, then
(Ii) In an autoclave, perform the main curing with saturated steam at 150 ° C. or more for 2 hours or more.
It is characterized by that.

  Hereinafter, the curing method of the present invention will be described with reference to the drawings.

  FIG. 2 shows an example of an embodiment of an autoclave curing of cement bond agglomerate. Kneading and crushing is performed by a kneading and pulverizing machine 5 while adding additive water 4a for kneading to the raw materials cut out from the fine ore hopper 1, auxiliary raw material hopper 2 and cement hopper 3 respectively at a predetermined ratio, and then for granulation. It granulates with the dish type granulator 6a, adding the addition water 4b. The granulated product (agglomerated ore) is removed undersize and oversize with a sieve 7.

  The process until removing the undersize and oversize of the granulated product (agglomerated ore) is the same as the conventional process. After removing the undersize and oversize of the granulated material (agglomerated ore), the loader 15 is designed so as not to give a drop impact as much as possible in the loading field 12 and has a hole on the lower surface. -It leaves still in the bucket 16 on the cart 11 for curing.

  After standing, the transportation / curing cart 11 is moved to the pre-curing site 13 and pre-curing of the agglomerates is performed for 2 hours or more by natural ventilation. Thereafter, the bucket 16 is placed in the autoclave device 14 and subjected to autoclave curing (main curing) with saturated steam at 150 ° C. or higher for 2 hours or longer.

  The pre-curing by natural ventilation is preferably performed for 4 hours or more, and the autoclave curing (main curing) is preferably performed for 4 hours or more. The saturated steam is preferably a saturated steam having a temperature of 170 ° C. or higher. It is more preferable to carry out autoclave curing (main curing) for 4 hours or more using saturated steam at 170 ° C. or higher.

  The autoclave curing in the curing method of the present invention has been actualized with reference to a slag aging treatment device using a carriage (see Patent Document 4), but the actualization is designed so as not to give a drop impact as much as possible. This was realized by being able to stand in a bucket on a transport / curing cart having an opening on the lower surface.

  Unlike slag, agglomerates immediately after agglomeration are vulnerable to impacts and drops, and cannot be handled by shovel cars like slag. If the agglomerate ore powder increases due to falling or the like, deterioration of air permeability during pre-curing, poor penetration of saturated steam into the agglomerate during autoclave curing, and the like occur.

  In order to avoid the occurrence of these phenomena, the stacker shown in Fig. 3 is free to be lifted and can be moved in the longitudinal direction of the carrier / curing cart with an opening on the lower surface (see arrows in the figure). did.

  With this stacker 15, the agglomerated ore after sieving can be placed in a bucket 16 on a transport / curing cart 11 having an opening on the lower surface with a drop distance as small as possible.

  In order to prevent interference between the loading machine 15 and the transport / curing cart 11 during the loading of the agglomerated ore, the peripheral portion is charged using the flow of the granulated material. The solid line in FIG. 3 shows the loading situation at the initial stage of loading, and the two-dot chain line shows the loading situation at the latter stage of loading.

  In FIG. 4, another example of embodiment of the autoclave curing of a cement bond agglomerated mineral is shown. The embodiment shown in FIG. 4 is basically the same as the embodiment shown in FIG. 2, but is an embodiment using a briquette machine 6b as a granulator.

  FIG. 5 shows still another example of an embodiment of an autoclave curing of cement bond agglomerated minerals. It is an embodiment using an extrusion molding machine 6c as a granulator.

  Table 1 shows the specifications of the equipment used in the curing method of the present invention. The specifications shown in Table 1 are examples, and the equipment used in the curing method of the present invention is not limited to this.

  In order to carry out the curing method of the present invention continuously and perform the curing work of cement bond agglomerates efficiently, it is necessary to prepare a plurality of carriages for curing and curing and to install a plurality of autoclave devices.

  FIG. 6 shows a series of time charts from loading for each carriage for transportation / curing to pre-curing, autoclave curing (main curing), dispensing, and waiting. The time chart shown in FIG. 6 is a time chart when 10 carriages / curing carts and 4 autoclave devices are used.

  Here, FIG. 7 shows the shape change of the agglomerate (granulated material) when autoclaving curing (main curing) is performed with saturated steam at 150 ° C. with the pre-curing time and main curing time changed.

  The result shown in FIG. 7 shows that a granulated product obtained by granulating a dry base containing 90% fine iron ore, 5% binder cement, and 5% fine limestone powder for adjusting the basicity is saturated at 150 ° C. When autoclave curing treatment is performed with steam, pre-curing time (30 ° C warm air is passed at 0.3 m / sec air velocity) and main curing time are changed, and the granulated material after curing (agglomeration) This is a change in the shape of the mineral.

  It can be seen that the pre-curing time is 2 hours or more and the main curing time is 2 hours or more, and the shape of the agglomerate is good.

  FIG. 8 shows the shape change of the agglomerate (granulated product) when autoclaving curing (main curing) is performed with saturated steam at 170 ° C. while changing the pre-curing time and the main curing time.

  The results shown in FIG. 8 show that a granulated product (agglomerated ore) granulated by blending 90% fine iron ore, 5% cement cement and 5% fine limestone powder for basicity adjustment on a dry basis. , Granulation after curing when experimenting by changing the pre-curing time (warm air at 30 ° C at a wind speed of 0.3 m / sec) and the main curing time when autoclaving with 170 ° C saturated steam It is a shape change of a thing (agglomerated mineral).

  From the above results, if the pre-curing time is insufficient, problems such as collapse of the granulated product (agglomerated ore) and partial peeling occur, but after pre-curing for 2 hours or more and for 2 hours or more. With autoclave curing (main curing), it is possible to obtain agglomerates with good shape after curing, and further, when precuring for 4 hours or more and main curing for 4 hours or more, there is no crack on the surface. It can be seen that a well-shaped agglomerate can be obtained.

FIG. 9 shows the relationship between the main curing temperature when autoclave curing is performed and the crushing strength of the agglomerated mineral after curing. The higher the main curing temperature, the higher the crushing strength of the agglomerated ore after curing. At the main curing temperature of 150 ° C. or higher, the strength of 6 N / mm ² required in the blast furnace can be secured. It can be seen that the longer the main curing time is, the higher the strength of the agglomerated mineral after curing is, but when the curing time is 4 hours or more, the strength increase tends to be saturated.

  Next, examples of the present invention will be described. The conditions in the examples are one example of conditions used for confirming the feasibility and effects of the present invention, and the present invention is based on this one example of conditions. It is not limited. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

[Example 1]
Table 2 shows an example of the results of autoclave curing performed before manufacturing the actual machine. Pre-cured for 2 hours or more, 2 hours or more to granulated product, granulated by blending 90% fine iron ore, 5% cement cement and 5% fine limestone powder for basicity adjustment. If this curing is carried out, the shape of the agglomerate is good. Further, if the pre-curing for 4 hours or more and the main curing for 4 hours or more are carried out, there will be no cracks on the surface, and an agglomerate with a very good shape will be obtained. I was able to get it.

Curing with saturated steam at 130 ° C. did not provide a crushing strength of 6 N / mm ² or more necessary for a blast furnace.

  In addition, the agglomerates were allowed to cool naturally after curing, but because the agglomerates had a high temperature after curing, evaporation occurred rapidly, and curing with saturated steam at 150 ° C or higher, moisture was 2% or less. became.

[Example 2]
The curing method of the present invention was performed according to the embodiment shown in FIG. The composition of the raw materials is the same as in Example 1, and is 90% fine iron ore, 5% cement for binder, and 5% fine powder for limestone for adjusting basicity.

  The transportation / curing cart 11 was moved from the loading field 12 to the pre-curing field 13, and pre-curing was performed by natural ventilation for 4 hours. The agglomerate had a temperature of 40 ° C. even in winter due to the temperature rise due to the crushing and kneading action in the ball mill 5 and the heat of hydration of the cement, satisfying the pre-curing conditions by natural ventilation. Even after autoclave curing, the agglomeration did not collapse or partly peeled off.

The transportation / curing cart 11 after the pre-curing was moved to the autoclave device 14, the bucket was put into the autoclave, and curing was performed with saturated steam at 170 ° C. for 4 hours. The crushing strength of the agglomerated ore after curing was 7 N / mm ² or more and the moisture was 2% or less, which was sufficient for use in a blast furnace.

In addition, to process granulated material of 50 t / hr on a wet base, a truck with a loading capacity of 32 m ³ can be loaded for 1 hour, 4 hours in advance, 4 hours in autoclave curing, and agglomerated ore after curing for waiting. It took 10 hours in total, 1 hour.

Example 3
The curing method of the present invention was carried out according to the embodiment shown in FIG. 4 (using a briquette machine for granulation). The composition of the raw materials is the same as in Example 1, and is 90% fine iron ore, 5% cement for binder, and 5% fine powder for limestone for adjusting basicity. The conditions for pre-curing and autoclave curing are the same as in Example 2. The strength of the agglomerated ore after curing was 8 N / mm ² or more and the water content was 1% or less, which was sufficient for use in a blast furnace.

Example 4
The curing method of the present invention was carried out according to the embodiment shown in FIG. 5 (using an extrusion molding machine for granulation). The composition of the raw materials is the same as in Example 1, and is 90% fine iron ore, 5% cement for binder, and 5% fine powder for limestone for adjusting basicity. The conditions for pre-curing and autoclave curing are the same as in Example 2. The strength of the agglomerated ore after curing was 7.5 N / mm ² or more and the water content was 2% or less, which was sufficient for use in a blast furnace.

  As described above, according to the present invention, a cement bond agglomerated mineral having a high strength and a reduced water content can be obtained in a short time with a good yield. Therefore, the cement bond agglomerate according to the present invention can be charged in a large amount into the blast furnace without being restricted by the moisture content of the blast furnace. Therefore, the present invention has high applicability in the steel industry.

DESCRIPTION OF SYMBOLS 1 Fine ore hopper 2 Auxiliary raw material hopper 3 Cement hopper 4a Additive water for kneading 4b Additive water for granulation 5 Kneading and crushing machine (ball mill)
6a Granulator (Pan pelletizer)
6b Granulator (briquette machine)
6c Granulator (extrusion molding machine)
7 Sieve 8 Primary Curing Yard 9 Stacker 10 Secondary Curing Yard or Ore Yard 11 Carriage and Curing Cart 12 Stacking Station 13 Pre-curing Station 14 Autoclave Device 15 Stacker 16 Bucket

Claims (4)

A method for curing cement bond agglomerates obtained by agglomerating fine ore with cement,
The (i) Cement the mass Naruko immediately after agglomerated with, the trolley for transport and curing with an opening on the lower surface, elevation freely by該台vehicle longitudinally movable stowage machine Leave still, pre-cured for 2 hours or more with natural ventilation, then
(Ii) In an autoclave, perform the main curing with saturated steam at 150 ° C. or more for 2 hours or more.
An autoclave curing method for cement bond agglomerated minerals.   The said pre-curing is performed for 4 hours or more, The autoclave curing method of the cement bond agglomerated minerals of Claim 1 characterized by the above-mentioned.   The autoclave curing method for cement bond agglomerated minerals according to claim 1 or 2, wherein the main curing is performed for 4 hours or more. The autoclave curing method for cement bond agglomerated minerals according to any one of claims 1 to 3, wherein saturated steam at 170 ° C or higher is used as the saturated steam .

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