【発明の詳細な説明】[Detailed description of the invention]
本発明は、高炉原料となる焼結鉱の製造方法に
関し、詳しくは焼結機へ供給される全原料の中の
20〜30％を占める返鉱の供給方法を変えることに
よつて生産性を改善した焼結鉱製造方法に関す
る。
高炉原料の70％以上を占める焼結鉱は、主とし
て、ドワイトロイド式の焼結機によつて製造され
ている。この焼結機による焼結鉱の製造は、エン
ドレス状に駆動するパレツトに各種鉱石、石灰石
等の副原料、コークス等の固体燃料を所定の割合
で配合混合した焼結原料を供給し、供給したその
焼結原料層の表面に点火炉により点火するととも
に、パレツトの下方に設けたウインドボツクスに
より吸気して、焼結原料層の上方から下方に向け
て焼成を伝播させ、下層まで焼成が進んだのち、
パレツトより排鉱されるよう焼結機を運転して製
造している。
焼結機より排鉱される焼結鉱は、非常に大きな
塊となつており、高炉原料として使用することが
できないため、破砕機にて粗破砕され、篩にて篩
われたのち、冷却機に装入され、100℃近くまで
冷却されたのち、高炉へと搬送され、搬送中の紛
焼結鉱を除くために再び篩にかけられたのち高炉
に装入される。
このように焼結機によつて得られる焼結鉱は、
各段階で篩われることによつて、５mm以下、５〜
10mm、10mm以上と３つの粒度に分割され、前記し
た高炉に装入される成品焼結鉱は、５mm以上の粒
度のものに限定され、５mm以下のものは、高炉原
料とした場合、炉内の通気性の悪化を招くとの理
由より高炉原料としては不適当であるため、返鉱
として鉱石とともに焼結原料として再循環されて
いる。
従来における焼結機のパレツトへの焼結原料の
供給方法は、第１図に示すように、８mm以下に微
粉砕された各種銘柄の鉱石１、石灰石等の副原料
２及びコークス粉等の固定燃料３等に、更に高炉
への使用不適当な５mm以下の返鉱４とを適正に配
合されて混合機５に装入され、この混合機５にお
いて水分を供給しながら、焼結原料として所定の
水分を保ち、かつ均一に混合されて焼結機６のパ
レツトに供給するようにしている。ところで、こ
のように配合された焼結原料の平均粒度は２mm程
度であつて、この焼結原料を直接パレツトに供給
されると、パレツト底面のグレートバー間より下
方に落下し、焼結鉱を得ることができないため、
焼結原料をパレツトに供給するに先だつて、５〜
10mmの焼結鉱と床敷鉱７として供給し、グレート
バー間の間隙をふさぐことにより焼結原料のパレ
ツトへの供給を可能にしている。
従来の焼結原料のパレツトへの供給において、
前記の如く、焼結原料の平均粒径が２mm程度と非
常に小径であるため床敷鉱の層厚を例えば50mmと
厚くせねばならないという問題があつた。また、
焼結原料に混合される返鉱は、一度焼成され副原
料等によつてCaO、MgO等と反応した鉱となつ
ており、鉱石の焼成温度よりも低い焼成温度とな
つているにもかかわらず、鉱石とともに配分され
ているために、低焼成温度が生かされず、従つて
固体燃料も鉱石原料のみの焼成並に添加せねばな
らないという問題があつた。なお、第１図におい
て、８は焼結鉱を示し、９は高炉を示す。
本発明は、前述の問題点を解消するためになさ
れたものであつて、焼結機パレツトの最下部に床
敷鉱層を形成させ、前記床敷鉱層上に返鉱層を形
成させ、前記返鉱層上に返鉱を含まない焼結原料
層を形成させて焼成することを特徴とするもので
ある。
以下、本発明法について、第２図をもとに説明
する。本発明法では、まず焼結機のパレツト上に
粒径５〜10mmの床敷鉱７を供給して床敷鉱層を形
成させる。その後、５mm以下であつて、鉱石等の
原料よりも粒径の大なる返鉱４を供給して返鉱層
を形成させる。鉱石等の平均粒径は２mm程度であ
るのに対し、返鉱４の平均粒径は４mm程度であ
り、返鉱４の粒径は鉱石の粒径よりも大きい粒径
である。従つて、この返鉱４を前記床敷鉱７層上
に供給することによつて、床敷鉱７層を貫通して
パレツトの下方に落下する量を十分に抑制でき、
よつて、前記床敷鉱７層を従来よりも薄い層とす
ることが可能となる。
発明者の実験によると、従来床敷鉱層をほぼ50
mmに保つていたものが、その上方に返鉱層を形成
させることによつて、30mmにまで薄くできること
が判明した。従つて薄くなつた層の分だけ高炉原
料として高炉に供給できる量が増加することにな
る。また、返鉱層の通気性は、従来の返鉱を混入
した焼結原料層の通気性に比較して粒度が大きく
なつた分だけ良くなり従つて生産性を向上させる
効果をもたらす。
次に、供給された返鉱４層の上部に返鉱を含ま
ない原料を提供する。この原料は、各種銘柄の鉱
石１、石灰石等の副原料２、及びコークス粉等の
固体燃料３等を所定の割合で各ホツパーから切出
して混合したものである。従来法では、この原料
にさらに返鉱を配合するのに対し、本発明法で
は、この原料のみに所定量の水分を添加しながら
混合機５で均一に混合して、前記返鉱４層の上に
供給するものである。従つて、パレツトにおける
充填層厚（パレツト底面から原料表面までの層
厚）が、従来法と本発明法とが同一厚さのとき
は、従来よりも床敷鉱層が薄くなつた分のみ原料
の供給量が増加することになつて、すなわち再循
環焼結鉱量が減ることになつて生産量が増加する
ことになる。また、従来のように返鉱に対して固
体燃料を添加せず、返鉱を除いた原料に対して固
体燃料を添加するものであるから、従来に比べ固
体燃料が節減されることになる。
本発明法における焼結鉱の製造は、高炉原料と
なる焼結鉱のうち粒径５〜10mmのものを床敷鉱と
して50mm以下30mmの範囲でパレツト上に供給し、
次いで、製造される焼結鉱中の20〜30％に相当す
る粒径５mm以下の返鉱全量を使用するように供給
し、更に、供給した返鉱層の上部に返鉱を含まな
い原料を所定量供給し、点火炉によつて前記原料
の表面に点火され、パレツトの下方に設けたウイ
ンドボツクスからの吸気によつて原料表面から下
方に向けて焼成を伝播させ、焼結鉱を得るもので
あり、返鉱層にあつては、固体燃料を添加してい
ないにもかかわらず、返鉱焼成温度が上方の原料
焼成温度よりも低いという利点によつて、返鉱上
方からの原料焼成の顕熱によつて焼成し焼結鉱を
得るものである。
実施例
本発明法と従来法における焼結鉱の製造法を、
内径250mm、底面からの高さ500mmの焼結鉱試験鍋
により試験した。第１表に原料配合割合、及び試
験鍋装入量を示し、第２表にその結果を示す。
The present invention relates to a method for producing sintered ore, which is a raw material for blast furnaces, and specifically relates to a method for producing sintered ore, which is a raw material for blast furnaces.
This invention relates to a sintered ore manufacturing method that improves productivity by changing the method of supplying return ore, which accounts for 20 to 30% of the total. Sintered ore, which accounts for more than 70% of blast furnace raw materials, is mainly produced using a Dwight Lloyd type sintering machine. The production of sintered ore using this sintering machine involves feeding a sintering raw material, which is a mixture of various ores, auxiliary raw materials such as limestone, and solid fuels such as coke, in a predetermined ratio to pallets that are driven in an endless manner. The surface of the sintered raw material layer was ignited by an ignition furnace, and air was sucked in by a wind box installed below the pallet to propagate the sintering process from above to below the sintered raw material layer, and the firing progressed to the lower layer. after,
It is manufactured by operating a sintering machine so that the ore is discharged from pallets. The sintered ore discharged from the sintering machine is in extremely large lumps and cannot be used as raw material for blast furnaces, so it is coarsely crushed in a crusher, sifted through a sieve, and then passed through a cooling machine. After being cooled to nearly 100℃, it is transported to a blast furnace, where it is sieved again to remove mixed sintered ore during transportation, and then charged into the blast furnace. The sintered ore obtained by the sintering machine in this way is
By being sieved at each stage, the
The finished sintered ore, which is divided into three particle sizes of 10 mm and 10 mm or more, and charged into the blast furnace described above, is limited to those with a particle size of 5 mm or more, and those with a particle size of 5 mm or less are used as blast furnace raw materials. Since it is unsuitable as a raw material for blast furnaces because it causes a deterioration in the permeability of the steel, it is recycled as a sintering raw material together with ore as return ore. The conventional method of supplying sintering raw materials to the pallets of a sintering machine is, as shown in Figure 1, by fixing various brands of ore 1 finely pulverized to 8 mm or less, auxiliary raw materials 2 such as limestone, and coke powder, etc. In addition to the fuel 3, return ore 4 of 5 mm or less, which is unsuitable for use in blast furnaces, is properly blended and charged into a mixer 5. While supplying moisture in the mixer 5, the return ore 4 is mixed as a sintering raw material. The water content of the sintering machine 6 is maintained, and the sintering machine 6 is supplied with a uniformly mixed mixture. By the way, the average particle size of the sintering raw material blended in this way is about 2 mm, and when this sintering raw material is directly supplied to the pallet, it falls below between the grating bars on the bottom of the pallet, and the sintered ore is Because it is not possible to obtain
Prior to supplying the sintering raw material to the pallet,
It is supplied as 10 mm sintered ore and bedding ore 7, and by closing the gap between the great bars, it is possible to supply the sintering raw material to the pallet. In the conventional supply of sintering raw materials to pallets,
As mentioned above, since the average grain size of the sintering raw material is very small, about 2 mm, there is a problem in that the layer thickness of the bedding ore has to be thick, for example, 50 mm. Also,
The return ore that is mixed with the sintering raw material is an ore that has been fired and reacted with CaO, MgO, etc. by the auxiliary raw materials, and even though the firing temperature is lower than that of the ore. Since it is distributed together with the ore, the low firing temperature cannot be taken advantage of, and there is a problem in that the solid fuel must be added at the same time as the ore raw material alone is fired. In addition, in FIG. 1, 8 represents sintered ore, and 9 represents a blast furnace. The present invention has been made to solve the above-mentioned problems, and includes forming a bedding ore layer at the lowest part of a sintering machine pallet, forming a return ore layer on the bedding ore layer, and forming a return ore layer on the bedding ore layer. It is characterized in that a sintered raw material layer containing no return ore is formed on top and fired. Hereinafter, the method of the present invention will be explained based on FIG. 2. In the method of the present invention, first, bedding ore 7 having a grain size of 5 to 10 mm is supplied onto a pallet of a sintering machine to form a bedding ore layer. Thereafter, return ore 4 having a particle size of 5 mm or less and larger than the raw material such as ore is supplied to form a return ore layer. The average particle size of ore etc. is about 2 mm, whereas the average particle size of the return ore 4 is about 4 mm, and the particle size of the return ore 4 is larger than the particle size of the ore. Therefore, by supplying this return ore 4 onto the 7 layers of bedding ore, the amount penetrating through the 7 layers of bedding ore and falling below the pallet can be sufficiently suppressed.
Therefore, it becomes possible to make the seven layers of bedding ore thinner than before. According to the inventor's experiments, the conventional bedding ore layer is approximately 50
It was found that what had been kept at 30 mm could be made as thin as 30 mm by forming a return layer above it. Therefore, the amount that can be supplied to the blast furnace as a blast furnace raw material increases by the amount of the thinner layer. In addition, the air permeability of the return ore layer is better as the grain size is increased compared to the air permeability of the conventional sintered raw material layer mixed with return ore, which has the effect of improving productivity. Next, a raw material containing no return ore is provided above the four layers of supplied return ore. This raw material consists of various brands of ore 1, auxiliary raw materials 2 such as limestone, solid fuel 3 such as coke powder, etc. cut out from each hopper at a predetermined ratio and mixed. In the conventional method, return ore is further blended with this raw material, whereas in the method of the present invention, a predetermined amount of water is added only to this raw material and mixed uniformly in the mixer 5 to form the four layers of return ore. It is something that is supplied to the top. Therefore, when the thickness of the packed layer in the pallet (thickness from the bottom of the pallet to the surface of the raw material) is the same between the conventional method and the method of the present invention, the amount of raw material is reduced by the thickness of the bedding ore layer, which is thinner than before. As the supply amount increases, that is, the amount of recycled sintered ore decreases, the production amount increases. Furthermore, since solid fuel is not added to the return ore as in the past, but solid fuel is added to the raw material excluding the return ore, the amount of solid fuel can be reduced compared to the past. In the production of sintered ore in the method of the present invention, sintered ore used as a blast furnace raw material with a particle size of 5 to 10 mm is fed onto a pallet as bedding ore in a range of 50 mm to 30 mm,
Next, the entire amount of return ore with a grain size of 5 mm or less, which corresponds to 20 to 30% of the sintered ore to be produced, is supplied so as to be used, and furthermore, a raw material that does not contain return ore is placed on the top of the supplied return ore layer. Sintered ore is obtained by supplying a fixed amount of raw material, igniting it on the surface of the raw material in an ignition furnace, and propagating the sintering process downward from the surface of the raw material by air intake from a wind box installed below the pallet. In the return ore layer, even though solid fuel is not added, the sensible heat of raw material firing from above the return ore is reduced due to the advantage that the return ore firing temperature is lower than the upper raw material firing temperature. The sintered ore is obtained by firing the sintered ore. Example The method for producing sintered ore using the method of the present invention and the conventional method,
The test was conducted using a sintered ore test pot with an inner diameter of 250 mm and a height of 500 mm from the bottom. Table 1 shows the mixing ratio of raw materials and the amount charged in the test pot, and Table 2 shows the results.
【表】【table】
【表】
本発明法による焼結鉱製造方法によれば、充填
層の上層から下層に至る粒度の偏析が大であるの
で通気性が向上し、生産性は大いに増大する。そ
して、返鉱層はコークスの添加を行わずとも上層
部からの顕熱によつて焼成が可能であるので、焼
成に要するコークスの原単位が大幅に低減され
る。また、通気性の改善に伴つて成品の品質も向
上する。[Table] According to the method for producing sintered ore according to the present invention, the segregation of particle sizes from the upper layer to the lower layer of the packed bed is large, so air permeability is improved and productivity is greatly increased. Since the return layer can be fired by sensible heat from the upper layer without adding coke, the basic unit of coke required for firing is significantly reduced. Furthermore, the quality of the finished product also improves as the air permeability improves.
【図面の簡単な説明】[Brief explanation of drawings]
第１図は従来法による焼結鉱製造方法の工程を
示す説明図。第２図は本発明法における工程説明
図。
１：鉱石、２：副原料、３：固体燃料、４：返
鉱、５：混合機、６：焼結機、７：床敷鉱、８：
焼結鉱、９：高炉。
FIG. 1 is an explanatory diagram showing the steps of a conventional method for producing sintered ore. FIG. 2 is a process explanatory diagram of the method of the present invention. 1: Ore, 2: Sub-raw material, 3: Solid fuel, 4: Return ore, 5: Mixer, 6: Sinterer, 7: Bed ore, 8:
Sintered ore, 9: Blast furnace.