JP2023167518A - Method for producing crude zinc oxide sintered ore - Google Patents

Method for producing crude zinc oxide sintered ore Download PDF

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JP2023167518A
JP2023167518A JP2022078775A JP2022078775A JP2023167518A JP 2023167518 A JP2023167518 A JP 2023167518A JP 2022078775 A JP2022078775 A JP 2022078775A JP 2022078775 A JP2022078775 A JP 2022078775A JP 2023167518 A JP2023167518 A JP 2023167518A
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exhaust gas
zinc oxide
crude zinc
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悟 高谷
Satoru Takaya
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Sumitomo Metal Mining Co Ltd
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Abstract

To suppress variation of the mercury concentration of slurry obtained by an exhaust gas treatment process in a method for producing crude zinc oxide sintered ore.SOLUTION: A method for producing crude zinc oxide sintered ore comprises: a reduction roasting process S10 of obtaining crude zinc oxide dust; a wet process S20 of applying a wet process to crude zinc oxide dust to obtain crude zinc oxide cake; a drying and heating process S30 of sintering the crude zinc oxide cake in a drying and heating furnace to obtain crude zinc oxide sintered ore; and an exhaust gas treatment process S40 of separating exhaust gas dust containing mercury from exhaust gas generated in the drying and heating process S30, and furthermore recovering the exhaust gas dust as exhaust gas dust slurry containing mercury, where exhaust gas dust precipitate is produced by a moisture percentage adjustment processing ST41 of drying the exhaust gas dust slurry obtained in the exhaust gas treatment process S40, and the exhaust gas dust precipitate is loaded into a drying and heating furnace which performs the drying and heating process S30 by using a predetermined amount segmenting device.SELECTED DRAWING: Figure 1

Description

本発明は、粗酸化亜鉛焼鉱の製造方法に関する。本発明は、詳しくは、鉄鋼ダスト等、亜鉛と共に不純物として微量の水銀を含有する原料を用いて、粗酸化亜鉛焼鉱を製造する場合に好適な粗酸化亜鉛焼鉱の製造方法に関する。 The present invention relates to a method for producing crude zinc oxide burnt ore. More specifically, the present invention relates to a method for producing crude zinc oxide sintered ore suitable for producing crude zinc oxide sintered ore using a raw material containing zinc and a trace amount of mercury as an impurity, such as iron and steel dust.

従来、亜鉛製錬所における亜鉛地金の原料として、粗酸化亜鉛が広く用いられている。亜鉛の原料となる粗酸化亜鉛は、例えば、鉄鋼業における高炉や電気炉等の製鋼炉から発生する鉄鋼ダストからも得ることができる。資源リサイクルの促進の観点からは、鉄鋼ダストの再利用は望ましいものである。しかし、一方で、鉄鋼ダストには、その主成分である酸化鉄や酸化亜鉛以外に、不純物として微量の水銀が含有されている。そして、最終的に製造プラントの処理系外に排出する処理済み排ガスの水銀濃度については、厳密に法定基準値を下回るように処理を行うことが必須とされている。 Conventionally, crude zinc oxide has been widely used as a raw material for zinc ingots in zinc smelters. Crude zinc oxide, which is a raw material for zinc, can also be obtained from steel dust generated from steelmaking furnaces such as blast furnaces and electric furnaces in the steel industry, for example. From the perspective of promoting resource recycling, reusing steel dust is desirable. However, on the other hand, iron and steel dust contains trace amounts of mercury as an impurity in addition to its main components, iron oxide and zinc oxide. It is essential that the mercury concentration of the treated exhaust gas, which is finally discharged outside the processing system of the manufacturing plant, be strictly below the legal standard value.

粗酸化亜鉛焼鉱の製造を行う、例えば、還元焙焼工程、湿式工程、乾燥加熱工程、排ガス処理工程からなる全体プロセスにおいて、上記の鉄鋼ダストに含まれる微量の水銀は、還元焙焼工程では、粗酸化亜鉛ダストに分配され、この粗酸化亜鉛ダストを処理する湿式工程では、粗酸化亜鉛ケーキに分配され、この粗酸化亜鉛ケーキを処理する乾燥加熱工程では、排ガスに分配され、続けて設けられている排ガス処理工程において、排ガスダスト、或いは、排ガス処理工程に設けられている吸着塔内の吸着剤に分配される。 In the overall process of manufacturing crude zinc oxide burnt ore, for example, consisting of a reduction roasting process, a wet process, a dry heating process, and an exhaust gas treatment process, trace amounts of mercury contained in the above steel dust are removed during the reduction roasting process. In the wet process of treating this crude zinc oxide dust, it is distributed into a crude zinc oxide cake, and in the dry heating process of treating this crude zinc oxide cake, it is distributed to the exhaust gas, and then In the exhaust gas treatment process, the exhaust gas is distributed to exhaust gas dust or to an adsorbent in an adsorption tower provided in the exhaust gas treatment process.

排ガスダストは、排ガス処理工程でスラリーとされた後、湿式工程に送られて粗酸化亜鉛ケーキの一部となるが、排ガス処理工程で得られるスラリー(以下、単に「スラリー」とも言う)を湿式工程に送り、乾燥加熱工程で処理すると、排ガス中の水銀濃度の値が大きくばらつくため、亜鉛を多く含むスラリー処理を抑制、或いは、中断せざるを得ず、亜鉛の実収率の低下、更には、抑制、或いは中断した際に、スラリーを中間物として抜き出して保管するための、人手と時間の浪費を余儀無くされていた。 After the exhaust gas dust is made into a slurry in the exhaust gas treatment process, it is sent to a wet process where it becomes part of the crude zinc oxide cake. When sent to a process and treated in a dry heating process, the value of the mercury concentration in the exhaust gas varies greatly, so it is necessary to suppress or interrupt the slurry treatment containing a large amount of zinc, resulting in a decrease in the actual yield of zinc, and even , when the process is suppressed or interrupted, it is necessary to extract and store the slurry as an intermediate, which necessitates a waste of manpower and time.

特許文献1には、粗酸化亜鉛焼鉱の製造を行う全体プロセスの中で、最終製品となる粗酸化亜鉛焼鉱を産出する乾燥加熱工程に装入する中間生成物の水銀含有率と製品産出量とに基づいて、水銀負荷量を求め、これを所定範囲内に維持する調整を行うことにより、最終的に製造プラントの処理系外に排出する処理済み排ガスの水銀濃度を高い精度で制御できることが示されている。しかしながら、スラリーを湿式工程に繰り返して、この湿式工程で得られる粗酸化亜鉛ケーキを乾燥加熱工程で処理すると、このスラリーの水銀濃度がばらつくため、粗酸化亜鉛ケーキ、即ち上記の中間生成物の水銀含有率自体がばらついてしまい、スラリーの繰り返しを中断する事態が発生していた。これを回避するために、排ガス処理工程で得られるスラリーの水銀濃度のばらつきを抑える技術的手段が求められていた。 Patent Document 1 describes the mercury content of an intermediate product charged into the drying and heating process to produce crude zinc oxide sintered ore, which is the final product, and the product yield in the overall process of manufacturing crude zinc oxide sintered ore. By determining the mercury load amount based on the amount and making adjustments to maintain it within a predetermined range, it is possible to control with high precision the mercury concentration in the treated exhaust gas that is ultimately discharged outside the processing system of the manufacturing plant. It is shown. However, when the slurry is repeatedly subjected to a wet process and the crude zinc oxide cake obtained in this wet process is treated in a dry heating process, the mercury concentration of this slurry varies. The content rate itself varied, resulting in a situation where slurry repetition was interrupted. In order to avoid this, there has been a need for a technical means to suppress variations in the mercury concentration of the slurry obtained in the exhaust gas treatment process.

特開2020-132970号公報Japanese Patent Application Publication No. 2020-132970

本発明は、粗酸化亜鉛焼鉱の製造において、排ガス処理工程で得られるスラリーの水銀濃度のばらつきを抑えることができる技術的手段を提供することを目的とする。 An object of the present invention is to provide a technical means that can suppress variations in the mercury concentration of a slurry obtained in an exhaust gas treatment step in the production of crude zinc oxide burnt ore.

本発明者らは、粗酸化亜鉛焼鉱の製造を行う全体プロセスの中で、従来は、湿式工程に繰り返されていた排ガス処理工程から得られる水銀を含有するスラリーを、水分率が適度に調整された澱物とした後に、定量切り出し装置を用いて、湿式工程を経由させずに、乾燥加熱工程を行う乾燥加熱炉に直接装入することにより、上記課題を解決することができることを見出し、本発明を完成するに至った。より具体的には、本発明は以下のものを提供する。 In the overall process of manufacturing crude zinc oxide burnt ore, the present inventors adjusted the moisture content of the slurry containing mercury obtained from the exhaust gas treatment process, which was conventionally repeated in the wet process, to an appropriate moisture content. We have discovered that the above problem can be solved by using a quantitative cut-out device to directly charge the precipitate into a drying and heating furnace that performs a drying and heating process without going through a wet process, The present invention has now been completed. More specifically, the present invention provides the following.

(1) 亜鉛を含有する原料から粗酸化亜鉛焼鉱を製造する粗酸化亜鉛焼鉱の方法であって、前記原料を還元焙焼して粗酸化亜鉛ダストを得る還元焙焼工程と、前記粗酸化亜鉛ダストに湿式処理を施し、水溶性不純物を除去して、粗酸化亜鉛ケーキを得る湿式工程と、前記粗酸化亜鉛ケーキを乾燥加熱炉で焼成し、粗酸化亜鉛焼鉱を得る乾燥加熱工程と、前記乾燥加熱工程で発生した排ガスから、水銀を含有する排ガスダストを分離し、更に、前記排ガスダストを、水銀を含有する排ガスダストスラリーとして回収する排ガス処理工程と、を備え、前記排ガス処理工程で得られる前記排ガスダストスラリーを、を所定の水分率となるように乾燥させる水分率調整処理によって排ガスダスト澱物とし、該排ガスダスト澱物を、定量切り出し装置を用いて、前記乾燥加熱工程を行う前記乾燥加熱炉に装入する、粗酸化亜鉛焼鉱の製造方法。 (1) A method for producing crude zinc oxide burnt ore from a raw material containing zinc, comprising: a reduction roasting step of reducing and roasting the raw material to obtain crude zinc oxide dust; A wet process in which zinc oxide dust is wet-treated to remove water-soluble impurities to obtain a crude zinc oxide cake; and a dry heating process in which the crude zinc oxide cake is fired in a dry heating furnace to obtain a crude zinc oxide sintered ore. and an exhaust gas treatment step of separating mercury-containing exhaust gas dust from the exhaust gas generated in the drying and heating step, and further recovering the exhaust gas dust as a mercury-containing exhaust gas dust slurry, the exhaust gas treatment step The exhaust gas dust slurry obtained in the step is dried to a predetermined moisture content to form an exhaust gas dust precipitate through a moisture content adjustment process, and the exhaust gas dust precipitate is subjected to the drying and heating step using a quantitative cutting device. A method for producing crude zinc oxide sintered ore, which is charged into the drying and heating furnace.

(1)の粗酸化亜鉛焼鉱の製造方法によれば、粗酸化亜鉛焼鉱の製造において、排ガス処理工程で得られるスラリーの水銀濃度のばらつきを抑えることができる。又、これにより、当該スラリーを粗酸化亜鉛焼鉱の製造を行う製造プラントの処理系内で安定的に処理することができるようになる。 According to the method for producing crude zinc oxide sintered ore (1), variations in the mercury concentration of the slurry obtained in the exhaust gas treatment step can be suppressed in the production of crude zinc oxide sintered ore. Moreover, this makes it possible to stably process the slurry within the processing system of a production plant that produces crude zinc oxide sintered ore.

(2) 前記排ガスダストスラリーの水分率が60%を超えていて、前記排ガスダスト澱物の水分率が20%以上60%以下の範囲内で定められた一定の水分率である、(1)に記載の粗酸化亜鉛焼鉱の製造方法。 (2) The moisture content of the exhaust gas dust slurry exceeds 60%, and the moisture content of the exhaust gas dust precipitate is a certain moisture content determined within a range of 20% to 60%; (1) The method for producing crude zinc oxide burnt ore described in .

(2)の粗酸化亜鉛焼鉱の製造方法によれば、排ガスダストスラリーを水分率が所定値に調整された澱物とすることで、スラリー濃度のばらつきをなくし、更に、この所定値を20%以上60%以下に規定することで、定量切り出し装置内での棚吊りの発生により乾燥加熱炉への円滑な装入が阻害されることも防ぐことができる。 According to the manufacturing method of crude zinc oxide sintered ore (2), by using the exhaust gas dust slurry as sediment whose moisture content is adjusted to a predetermined value, variations in the slurry concentration are eliminated, and furthermore, this predetermined value is adjusted to 20%. % or more and 60% or less, it is also possible to prevent smooth charging into the drying and heating furnace from being hindered due to the occurrence of shelf suspension in the quantitative cutting device.

(3) 前記排ガスダストスラリーを、天日乾燥により水分率40%超え60%以下まで乾燥させた後、水分率が10%以下の微粉末状の亜鉛含有原料と混合することによって水分率を調整して、水分率40%以下の前記排ガスダスト澱物を得る、(1)又は(2)に記載の粗酸化亜鉛焼鉱の製造方法。 (3) After drying the exhaust gas dust slurry in the sun to a moisture content of more than 40% and less than 60%, the moisture content is adjusted by mixing it with a finely powdered zinc-containing raw material with a moisture content of less than 10%. The method for producing crude zinc oxide sintered ore according to (1) or (2), wherein the exhaust gas dust precipitate having a moisture content of 40% or less is obtained.

(3)の粗酸化亜鉛焼鉱の製造方法によれば、天日乾燥と微粉末状の追加原料との混合という2つの処理の組合せによって、乾燥用の機器等の導入に頼らずに、最小限の追加処理コストで、上記の排ガスト澱物を得るための水分率調整処理を行うことができるので、より経済的に、(1)又は(2)に記載の粗酸化亜鉛焼鉱の製造方法の奏する上記効果を享受することができる。 According to the manufacturing method of crude zinc oxide sintered ore (3), by combining the two processes of drying in the sun and mixing with additional raw materials in the form of fine powder, it is possible to minimize Since the moisture content adjustment treatment for obtaining the above-mentioned exhaust gas precipitate can be performed with a limited additional processing cost, the crude zinc oxide sintered ore described in (1) or (2) can be produced more economically. The above effects of the method can be enjoyed.

(4) 前記原料が鉄鋼ダストである、(1)又は(2)に記載の粗酸化亜鉛焼鉱の製造方法。 (4) The method for producing crude zinc oxide sintered ore according to (1) or (2), wherein the raw material is steel dust.

(4)の粗酸化亜鉛焼鉱の製造方法によれば、資源リサイクルの促進の観点からは望ましい原料である一方で、不純物として水銀を含有し、その含有量のばらつきも大きい鉄鋼ダストを、製造プラントの処理系内で安定的に処理することができるようになる。 According to the method for producing crude zinc oxide sintered ore (4), steel dust, which is a desirable raw material from the perspective of promoting resource recycling, contains mercury as an impurity and its content varies widely. It becomes possible to perform stable processing within the processing system of the plant.

本発明によれば、粗酸化亜鉛焼鉱の製造において、排ガス処理工程で得られるスラリーの水銀濃度のばらつきを抑えることができる。又、これにより、当該スラリーを粗酸化亜鉛焼鉱の製造を行う製造プラントの処理系内で安定的に処理することができるようになる。 According to the present invention, in the production of crude zinc oxide sintered ore, it is possible to suppress variations in the mercury concentration of the slurry obtained in the exhaust gas treatment step. Moreover, this makes it possible to stably process the slurry within the processing system of a production plant that produces crude zinc oxide sintered ore.

本発明の粗酸化亜鉛焼鉱の製造方法のフローの一例を示すフロー図である。It is a flow diagram showing an example of the flow of the manufacturing method of crude zinc oxide sintered ore of the present invention. 粗酸化亜鉛焼鉱の製造を従来方法で実施した時の乾燥加熱工程から排出される排ガス中の水銀濃度の推移と、同製造を本発明の製造方法で実施した時の同排ガス中の水銀濃度の推移と、を示すグラフ図である。Changes in the concentration of mercury in the exhaust gas discharged from the drying and heating process when crude zinc oxide sintered ore is produced using the conventional method, and the concentration of mercury in the exhaust gas when the same production is carried out using the production method of the present invention. It is a graph diagram showing the transition of .

<全体プロセス>
本発明の粗酸化亜鉛焼鉱の製造方法は、粗酸化亜鉛焼鉱の製造を行う全体プロセスのうち、還元焙焼工程S10、湿式工程S20、乾燥加熱工程S30、及び、排ガス処理工程S40を含んでなる複合的なプロセスである。これらの各部分工程のうち、湿式工程S20で得られる粗酸化亜鉛ケーキを焼成して製品である粗酸化亜鉛焼鉱を産出する工程である乾燥加熱工程S30から、水銀を含有する排ガスが排出される。本発明の粗酸化亜鉛焼鉱の製造方法は、これらの必須の4工程の他に、更に、排水処理工程S50を加えた全体プロセスとしての実施を、その代表的な実施態様とする全体プロセスである。
<Overall process>
The method for producing crude zinc oxide burnt ore of the present invention includes a reduction roasting step S10, a wet process S20, a dry heating step S30, and an exhaust gas treatment step S40 in the overall process for producing crude zinc oxide burnt ore. It is a complex process consisting of Among these partial steps, exhaust gas containing mercury is discharged from the drying and heating step S30, which is a step in which the crude zinc oxide cake obtained in the wet step S20 is fired to produce crude zinc oxide burnt ore as a product. Ru. The method for producing crude zinc oxide sintered ore of the present invention is an overall process in which, in addition to these four essential steps, a wastewater treatment step S50 is added as a whole process, which is a typical embodiment thereof. be.

そして、本発明の粗酸化亜鉛焼鉱の製造方法は、このような全体プロセスの中で、従来プロセスにおいては、湿式工程S20に送られて粗酸化亜鉛ケーキの一部となった後に乾燥加熱工程S30に装入されていた排ガス処理工程S40から得られる水銀を含有するスラリーを、水分率が適度に調整された澱物とした後に、湿式工程S20を経由させずに、定量切り出し装置を用いて、乾燥加熱工程S30に直接装入するようにした点を主たる特徴とするプロセスである。尚、本発明の粗酸化亜鉛焼鉱の製造方法は、特に、水銀の濃度のばらつきが大きい鉄鋼ダストを主たる原料として用いる製造プラントにおいて、とりわけ有利な効果を発揮する。 In the method for producing crude zinc oxide sintered ore of the present invention, in the conventional process, the crude zinc oxide burnt ore is sent to the wet step S20 and becomes a part of the crude zinc oxide cake, and then the drying and heating step is performed. After turning the mercury-containing slurry obtained from the exhaust gas treatment step S40, which had been charged into S30, into a precipitate with an appropriately adjusted moisture content, it is processed using a quantitative cutting device without passing through the wet step S20. , is a process whose main feature is that it is directly charged into the drying and heating step S30. The method for producing crude zinc oxide sintered ore of the present invention exhibits particularly advantageous effects particularly in production plants that use steel dust as a main raw material, which has large variations in mercury concentration.

<還元焙焼工程>
還元焙焼工程S10は、通常、大型の回転式加熱炉である還元焙焼ロータリーキルン(RRK)によって、鉄鋼ダスト等の原料(一次原料)を、還元剤と共に高温で焙焼する工程である。還元焙焼処理の焙焼温度については、被処理物の最高温度が1050℃以上1200℃以下程度となるように還元焙焼ロータリーキルン(RRK)の炉内温度を保持管理することが好ましい。還元焙焼ロータリーキルン(RRK)の炉内で、鉄鋼ダスト等の原料は還元焙焼され、揮発した金属亜鉛が炉内で再酸化されて粉状の酸化亜鉛となる。粉状の酸化亜鉛は、還元焙焼ロータリーキルンからの排出ガス(RRK排出ガス)と共に集塵機に導入されダストとして捕集される。このとき、原料に含まれていた水銀も、上記RRK排ガスへの活性炭の噴霧と集塵等により同様にダストとして捕集され、水銀を含有するこれらのダストが、粗酸化亜鉛ダストとして次工程である湿式工程に装入される。尚、この還元焙焼工程S10において揮発せずにキルン内に残った還元焙焼残渣は、通常、含鉄クリンカーと称する製品としてキルン排出端より回収され、還元された鉄分が多く含有されるため、鉄鋼メーカー向けの鉄原料等として払い出される。
<Reduction roasting process>
The reduction roasting step S10 is a step in which a raw material (primary raw material) such as steel dust is roasted together with a reducing agent at a high temperature using a reduction roasting rotary kiln (RRK), which is usually a large rotary heating furnace. Regarding the roasting temperature in the reduction roasting treatment, it is preferable to maintain and manage the furnace temperature of the reduction roasting rotary kiln (RRK) so that the maximum temperature of the object to be treated is approximately 1050°C or higher and 1200°C or lower. In the furnace of a reduction roasting rotary kiln (RRK), raw materials such as steel dust are reduced and roasted, and the volatilized metallic zinc is reoxidized in the furnace to become powdered zinc oxide. Powdered zinc oxide is introduced into a dust collector together with the exhaust gas (RRK exhaust gas) from the reduction roasting rotary kiln and is collected as dust. At this time, the mercury contained in the raw material is also collected as dust by spraying activated carbon onto the RRK exhaust gas and collecting dust, and these mercury-containing dusts are processed as crude zinc oxide dust in the next process. Charged to a wet process. Note that the reduced roasting residue remaining in the kiln without being volatilized in this reducing roasting step S10 is usually recovered from the kiln discharge end as a product called iron-containing clinker, and contains a large amount of reduced iron. It is sold as iron raw material for steel manufacturers.

<湿式工程>
湿式工程S20は、還元焙焼工程S10において回収された上記の粗酸化亜鉛ダストを、工業用水等でレパルプし、塩素、カドミウム等の水溶性不純物を分離する湿式処理を行う工程である。尚、湿式工程S20には、鉄鋼ダスト等の一次原料が上流工程である還元焙焼工程S10を経て生成された粗酸化亜鉛ダストの他に、粗酸化亜鉛ダストと同等の化学組成であり亜鉛を含有する粗酸化亜鉛粉等の二次原料(湿式工程で処理する粗酸化亜鉛は、乾燥加熱工程S30に装入する購入粗酸化亜鉛とは区別して「二次原料」と称する)も、還元焙焼工程S10を経ずに、直接装入され、一次原料から得られる粗酸化亜鉛ダストと同様の処理が行われる。
<Wet process>
The wet process S20 is a process in which the crude zinc oxide dust recovered in the reduction roasting process S10 is repulped with industrial water or the like, and subjected to a wet process to separate water-soluble impurities such as chlorine and cadmium. In addition, in the wet process S20, primary raw materials such as steel dust are used in addition to the crude zinc oxide dust produced through the upstream reduction roasting process S10, which has the same chemical composition as the crude zinc oxide dust and contains zinc. Secondary raw materials such as crude zinc oxide powder (the crude zinc oxide treated in the wet process is referred to as "secondary raw material" to distinguish it from the purchased crude zinc oxide charged in the drying and heating process S30) are also subjected to reduction roasting. The zinc oxide dust is directly charged without going through the calcination step S10, and is subjected to the same treatment as the crude zinc oxide dust obtained from the primary raw material.

上記の分離処理を経てスラリーとなった粗酸化亜鉛ダストは、pH調整及び濃縮処理、脱水処理が行われることにより、粗酸化亜鉛ケーキとされて、次工程である乾燥加熱工程S30に装入される。上記の濃縮及び脱水処理については、シックナー等の重力沈降式スラリー濃縮装置や真空脱水機等の脱水装置を適宜用いることができる。 The crude zinc oxide dust that has become a slurry through the above separation process is subjected to pH adjustment, concentration treatment, and dehydration treatment to become a crude zinc oxide cake, which is then charged to the next step, drying and heating step S30. Ru. For the above-mentioned concentration and dehydration treatment, a gravity sedimentation type slurry concentration device such as a thickener or a dehydration device such as a vacuum dehydrator can be used as appropriate.

<乾燥加熱工程>
乾燥加熱工程S30は、湿式工程S20で得た粗酸化亜鉛ケーキを、乾燥加熱ロータリーキルン(DRK)等の乾燥加熱炉に装入して焼成する工程である。この乾燥加熱工程S30により、水銀を含む残留不純物を揮発させて、高品位の粗酸化亜鉛焼鉱を得ることができる。乾燥加熱処理の焼成温度については、乾燥加熱ロータリーキルン(DRK)等から産出される際の被焼成物の温度が900℃以上1250℃以下の範囲となるように炉内温度を保持管理する。
<Dry heating process>
The dry heating step S30 is a step in which the crude zinc oxide cake obtained in the wet step S20 is charged into a dry heating furnace such as a dry heating rotary kiln (DRK) and baked. Through this drying and heating step S30, residual impurities including mercury can be volatilized, and high-grade crude zinc oxide sintered ore can be obtained. Regarding the firing temperature in the dry heating treatment, the furnace temperature is maintained and managed so that the temperature of the fired product when produced from a dry heating rotary kiln (DRK) or the like is in the range of 900° C. or higher and 1250° C. or lower.

又、本発明の粗酸化亜鉛焼鉱の製造方法においては、従来プロセスにおいては、湿式工程S20に繰り返されていた排ガス処理工程S40で得られる排ガスダストスラリーを、水分率調整処理ST41によって排ガスダスト澱物とした上で、当該排ガスダスト澱物を、湿式工程S20を経由させずに、直接、乾燥加熱工程S30を行う乾燥加熱炉に装入する。又、排ガスダスト澱物の乾燥加熱炉への装入は、定量切り出し装置を用いて行う。尚、本発明の粗酸化亜鉛焼鉱の製造方法においては、上記の排ガスダストスラリーの全部を排ガスダスト澱物として乾燥加熱工程S30を行う乾燥加熱炉に装入することが好ましいが、本発明の効果を阻害しない範囲で、一部の排ガスダストスラリーを従前通りに湿式工程に繰り返してもよい。 In addition, in the method for producing crude zinc oxide sintered ore of the present invention, the exhaust gas dust slurry obtained in the exhaust gas treatment step S40, which was repeated in the wet step S20 in the conventional process, is converted into exhaust gas dust sludge by the moisture content adjustment treatment ST41. After converting into a product, the exhaust gas dust precipitate is directly charged into a drying and heating furnace in which a drying and heating process S30 is performed, without passing through the wet process S20. Further, the exhaust gas dust precipitate is charged into the drying and heating furnace using a quantitative cutting device. In the method for producing crude zinc oxide sintered ore of the present invention, it is preferable to charge the entire exhaust gas dust slurry as exhaust gas dust precipitate into a drying and heating furnace in which the drying and heating step S30 is performed. A part of the exhaust gas dust slurry may be repeatedly subjected to the wet process as before, as long as the effect is not impaired.

上記の排ガスダスト澱物は、水分率調整処理ST41によって、水分率のばらつきが十分に低減されているので、これに起因する排ガスダスト澱物中の水銀濃度の変動は十分に抑制されている。又、排ガスダストスラリーの固形分に含まれる水銀濃度のばらつき、即ち、この排ガスダスト澱物自体の水銀濃度にばらつきがある場合には、乾燥加熱工程S30から排出される排ガス中の水銀濃度をモニタリングしながら、排ガスダスト澱物を乾燥加熱炉に装入する切り出し装置の切り出し量を当該水銀濃度に応じて増減させる調整を行うことによって、水銀濃度の過剰な変動を回避しながら、排ガスダストスラリー(排ガスダスト澱物)の処理を継続することができる。尚、「排ガスダスト澱物」、及び、これを得るための「水分率調整処理ST41」の詳細については後述する。 In the above-mentioned exhaust gas dust precipitate, the variation in moisture content is sufficiently reduced by the moisture content adjustment process ST41, and therefore the fluctuation in the mercury concentration in the exhaust gas dust precipitate caused by this is sufficiently suppressed. In addition, if there are variations in the mercury concentration contained in the solid content of the exhaust gas dust slurry, that is, there are variations in the mercury concentration in the exhaust gas dust precipitate itself, the mercury concentration in the exhaust gas discharged from the drying and heating step S30 is monitored. At the same time, by adjusting the cutting amount of the cutting device that charges the exhaust gas dust precipitate into the drying and heating furnace according to the mercury concentration, the exhaust gas dust slurry ( The treatment of exhaust gas dust sediments can be continued. The details of the "exhaust gas dust precipitate" and the "moisture content adjustment process ST41" for obtaining this will be described later.

尚、乾燥加熱工程S30を行う乾燥加熱炉においては、一次原料由来及び二次原料由来の水銀に加えて、粗酸化亜鉛ケーキ、及び、水分率調整処理ST41を経て繰り返された排ガスダスト澱物に含有される水銀のほぼ全量が、排ガス側に分配されて後段の排ガス処理工程S40に送られる。 In addition, in the drying and heating furnace that performs the drying and heating step S30, in addition to mercury derived from the primary raw material and secondary raw material, the crude zinc oxide cake and the exhaust gas dust precipitate that has been repeatedly subjected to the moisture content adjustment process ST41 are Almost the entire amount of mercury contained is distributed to the exhaust gas side and sent to the subsequent exhaust gas treatment step S40.

<排ガス処理工程>
排ガス処理工程S40は、乾燥加熱工程S30で発生した水銀等を含有する排ガスを除塵、無害化して水銀及びその他の不純物を除去し、無害化された処理済み排ガスとする工程である。この工程を行う設備としては、洗浄塔、湿式電気集塵機、水銀吸着剤が充填されている充填塔の組合せが一般的である。尚、上記の水銀吸着剤としては、例えば、粒コークス等の炭素化合物の表面に、銅精鉱、亜鉛精鉱、鉛精鉱等から選択される1種以上の硫化物を付着させたものが広く用いられている。
<Exhaust gas treatment process>
The exhaust gas treatment step S40 is a step in which the exhaust gas containing mercury and the like generated in the drying and heating step S30 is dedusted and rendered harmless to remove mercury and other impurities, thereby producing a treated exhaust gas made harmless. The equipment for carrying out this process is generally a combination of a washing tower, a wet electrostatic precipitator, and a packed tower filled with a mercury adsorbent. The above-mentioned mercury adsorbent is, for example, one in which one or more sulfides selected from copper concentrate, zinc concentrate, lead concentrate, etc. are attached to the surface of a carbon compound such as granular coke. Widely used.

上記の構成からなる設備において排ガス処理工程S40を行う場合においては、排ガス中の水銀は95%程度の回収率で充填塔内の水銀吸着剤に吸着回収されるが、上述の通り、水銀を含む排ガスダストをスラリーとしたもの(排ガスダストスラリー)は、主成分が酸化亜鉛であることから、従来は、この排ガスダストスラリーを、湿式工程S20に繰り返して循環装入することにより、金属資源の有効利用が図られている。これに対して、本発明の粗酸化亜鉛焼鉱の製造方法においては、以下に詳細を説明する水分率調整処理ST41によって、排ガスダストスラリーを、水分率が適度に調整されている澱物(排ガスダスト澱物)とした上で、乾燥加熱工程S30に繰り返すように排ガスダストスラリーの処理の流れを変更している。 When performing the exhaust gas treatment step S40 in the equipment configured as described above, mercury in the exhaust gas is adsorbed and recovered by the mercury adsorbent in the packed tower at a recovery rate of about 95%, but as described above, mercury is contained in the exhaust gas. Since the main component of a slurry made from exhaust gas dust (exhaust gas dust slurry) is zinc oxide, conventionally, this exhaust gas dust slurry is repeatedly cyclically charged into the wet process S20 to reduce the effectiveness of metal resources. It is planned to be used. On the other hand, in the method for producing crude zinc oxide sintered ore of the present invention, the exhaust gas dust slurry is converted into sludge (exhaust gas The process flow of the exhaust gas dust slurry is changed so that the exhaust gas dust slurry is treated as dust precipitate) and then the drying and heating step S30 is repeated.

[水分率調整処理]
水分率調整処理ST41は、排ガス処理工程で得られる排ガスダストスラリーを、所定の水分率となるように乾燥させる水分率調整処理によって排ガスダスト澱物とする処理である。排ガスダストスラリーの水分率は、60%を超えていて、且つ、ばらつきも大きいことが一般的である。水分率調整処理ST41によって、このような性状のスラリーを、適度に乾燥させることで、水分率のばらつきが小さい澱物とすることができる。
[Moisture content adjustment process]
The moisture content adjustment process ST41 is a process in which the exhaust gas dust slurry obtained in the exhaust gas treatment process is dried to a predetermined moisture content, thereby converting it into exhaust gas dust precipitate. Generally, the moisture content of exhaust gas dust slurry exceeds 60% and varies widely. By appropriately drying the slurry having such properties through the moisture content adjustment process ST41, it is possible to turn the slurry into sediment with a small variation in moisture content.

排ガスダスト澱物の水分率は、20%以上60%以下であればよく、20%以上50%以下であることが好ましく、20%以上40%以下であることがより好ましい。「所定の水分率」はこの範囲内で適宜設定することができる。尚、排ガスダスト澱物の水分率の管理値として規定される「所定の水分率」には、一定範囲内の変動幅があってもよい。例えば、「所定の水分率」を30%±5%と言うように、所定範囲内の幅をもたせて規定することができる。この場合の水分率の変動幅は±10%以内とすることが好ましく、±5%以内とすることがより好ましい。 The moisture content of the exhaust gas dust sediment may be 20% or more and 60% or less, preferably 20% or more and 50% or less, and more preferably 20% or more and 40% or less. The "predetermined moisture content" can be appropriately set within this range. Note that the "predetermined moisture content" defined as the control value of the moisture content of the exhaust gas dust precipitate may have a fluctuation range within a certain range. For example, the "predetermined moisture content" can be defined within a predetermined range, such as 30%±5%. In this case, the fluctuation range of the moisture content is preferably within ±10%, more preferably within ±5%.

水分率調整処理ST41の具体的手段は特に限定されないが、一例として、排ガスダストスラリーを、天日乾燥により水分率40%超え60%以下まで乾燥させた後、水分率が10%以下の微粉末状の亜鉛含有原料と混合することによって水分率を調整して、水分率40%以下の前記排ガスダスト澱物を得る処理方法を好ましい実施態様の一例として挙げることができる。 The specific means for the moisture content adjustment process ST41 is not particularly limited, but as an example, after drying the exhaust gas dust slurry in the sun to a moisture content of more than 40% and less than 60%, it is turned into fine powder with a moisture content of less than 10%. An example of a preferable embodiment is a treatment method in which the moisture content is adjusted by mixing with a zinc-containing raw material of 40% or less to obtain the exhaust gas dust precipitate having a moisture content of 40% or less.

水分率調整処理ST41は、或いは、上記の天日乾燥に替えて、ベルト式脱水機等の脱水機を用いて、例えば、水分率20%以上30%以下の脱水ケーキとして抜き出すことによって行い、この脱水ケーキを定量切り出し装置により切り出すこととしてもよい。 Alternatively, instead of the above-mentioned solar drying, the moisture content adjustment process ST41 is performed by using a dehydrator such as a belt-type dehydrator to extract a dehydrated cake with a moisture content of 20% or more and 30% or less. The dehydrated cake may be cut out using a quantitative cutting device.

<排水処理工程>
排水処理工程S50は、湿式工程S20において粗酸化亜鉛ダストから分離された塩素、カドミウム等の水溶性不純物を高濃度で含有する廃液から、カドミウム等の一部の重金属を除去し、その後、廃液中に微量に残留した重金属を消石灰による中和処理により沈殿除去し、最終的にpH調整処理を施して無害の処理済み排水とする工程である。
<Wastewater treatment process>
In the wastewater treatment process S50, some heavy metals such as cadmium are removed from the wastewater containing high concentrations of water-soluble impurities such as chlorine and cadmium separated from the crude zinc oxide dust in the wet process S20, and then This is a process in which trace amounts of heavy metals remaining in the wastewater are removed by precipitation through neutralization with slaked lime, and finally pH adjustment is performed to produce harmless treated wastewater.

図1に示す全体プロセスを実施可能な粗酸化亜鉛焼鉱の製造プラントにおいて、本発明の「粗酸化亜鉛焼鉱の製造方法」によって粗酸化亜鉛焼鉱製造を行う試験操業を行った。実施例及び比較例の試験操業において、乾燥加熱工程から排出される排ガス中の水銀濃度の推移を観察することにより、本発明の効果を検証した。尚、試験操業は、比較例の操業を、第1日から第7日として先行して行い、この後に、実施例の操業を、第8日から第14日として行った。結果は図2に示す通りであった。尚、同図に示した水銀濃度指数とは、所定の水銀濃度を100として、水銀濃度を指数化した値である。又、両者の操業において実際に処理することができた排ガスダストスラリー(或いは、排ガスダスト澱物)の量(表1において「排ガスダスト処理量」と記す)の推移を下記表1に示す。 In a crude zinc oxide sintered ore production plant capable of carrying out the overall process shown in FIG. 1, a test operation was conducted to produce crude zinc oxide sintered ore according to the "method for producing crude zinc oxide sintered ore" of the present invention. In test operations of Examples and Comparative Examples, the effects of the present invention were verified by observing changes in mercury concentration in exhaust gas discharged from the drying and heating process. In the test operation, the operation of the comparative example was conducted from the 1st day to the 7th day, and then the operation of the example was conducted from the 8th day to the 14th day. The results were as shown in FIG. The mercury concentration index shown in the figure is a value obtained by converting the mercury concentration into an index, with a predetermined mercury concentration being 100. In addition, the following Table 1 shows the change in the amount of exhaust gas dust slurry (or exhaust gas dust precipitate) that could actually be treated in both operations (denoted as "exhaust gas dust treatment amount" in Table 1).

[実施例]
排ガス処理工程から得られる「排ガスダストスラリー」の全量を抜き取り、既に抜き取ってあった同量の「排ガスダストスラリー」を天日で水分率40%まで乾燥させて得た「排ガスダスト澱物」、及び、湿式工程で得た「粗酸化亜鉛ケーキ」を、乾燥加熱工程に装入する操業を7日間行った。「排ガスダストスラリー」の抜き取り量と「排ガスダスト澱物」の装入量は、何れも乾燥重量において同量である、1~2t/hとした。又、「粗酸化亜鉛ケーキ」の装入量は、5~6t/hとし、乾燥加熱工程への「排ガスダスト澱物」及び「粗酸化亜鉛ケーキ」の合計装入量は、6~8t/hとした。
[Example]
"Exhaust gas dust sludge" obtained by extracting the entire amount of "exhaust gas dust slurry" obtained from the exhaust gas treatment process and drying the same amount of "exhaust gas dust slurry" that had already been extracted under the sun to a moisture content of 40%, Then, an operation was conducted for 7 days in which the "crude zinc oxide cake" obtained in the wet process was charged into the dry heating process. The amount of "exhaust gas dust slurry" extracted and the amount of "exhaust gas dust precipitate" charged were both the same amount in dry weight, 1 to 2 t/h. In addition, the charging amount of "crude zinc oxide cake" is 5 to 6 t/h, and the total charging amount of "exhaust gas dust precipitate" and "crude zinc oxide cake" to the drying and heating process is 6 to 8 t/h. It was set as h.

[比較例]
排ガス処理工程から得られる「排ガスダストスラリー」の抜き取りは行わず、その全量を湿式工程に繰返した。「排ガスダスト澱物」の装入も行わずに、湿式工程で得た「粗酸化亜鉛ケーキ(排ガスダストスラリーを含有するケーキ)」を、乾燥加熱工程に装入する操業を7日間行った。尚、比較例の操業では、第5日目において、排ガス中の水銀濃度の値の急上昇により、「排ガスダストスラリー」の湿式工程への繰り返しを一時的に制限せざるを得ない状態となり8時間にわたってスラリーの処理を制限している。
[Comparative example]
The "exhaust gas dust slurry" obtained from the exhaust gas treatment process was not extracted, and the entire amount was repeated in the wet process. An operation was carried out for 7 days in which the "crude zinc oxide cake (cake containing exhaust gas dust slurry)" obtained in the wet process was charged to the drying and heating process without charging the "exhaust gas dust precipitate". In addition, in the operation of the comparative example, on the 5th day, due to a sudden increase in the mercury concentration in the exhaust gas, it was necessary to temporarily restrict the repetition of the "exhaust gas dust slurry" to the wet process, and the operation was continued for 8 hours. The processing of slurry is restricted over the entire range.

Figure 2023167518000002
Figure 2023167518000002

図1に示す通り、本発明の「粗酸化亜鉛焼鉱の製造方法」の採用により、排ガス中水銀濃度指数のばらつきは顕著に低減した。具体的に、排ガス中水銀濃度指数の標準偏差(σ)は、107から32に減少している。又、これにより、表1に示すように、排ガスダスト澱物(或いは、排ガスダストスラリー)の処理量も大幅に増加させることができた。以上の結果より、本発明の「粗酸化亜鉛焼鉱の製造方法」は、粗酸化亜鉛焼鉱の製造において、排ガス処理工程で得られるスラリーの水銀濃度のばらつきを抑えることができ、これにより、当該スラリーを粗酸化亜鉛焼鉱の製造を行う製造プラントの処理系内で安定的に処理することができるプロセスであることが確認された。 As shown in FIG. 1, by employing the "method for producing crude zinc oxide sintered ore" of the present invention, the variation in the mercury concentration index in exhaust gas was significantly reduced. Specifically, the standard deviation (σ) of the mercury concentration index in exhaust gas decreased from 107 to 32. Furthermore, as shown in Table 1, the amount of exhaust gas dust precipitate (or exhaust gas dust slurry) to be treated could also be significantly increased. From the above results, the "method for producing crude zinc oxide sintered ore" of the present invention can suppress variations in the mercury concentration of the slurry obtained in the exhaust gas treatment process in the production of crude zinc oxide sintered ore, and thereby, It was confirmed that this is a process that can stably process the slurry in the processing system of a production plant that produces crude zinc oxide sintered ore.

S10 還元焙焼工程
S20 湿式工程
S30 乾燥加熱工程
S40 排ガス処理工程
ST41 水分率調整処理
S50 排水処理工程
S10 Reduction roasting process S20 Wet process S30 Drying and heating process S40 Exhaust gas treatment process ST41 Moisture content adjustment process S50 Wastewater treatment process

Claims (4)

亜鉛を含有する原料から粗酸化亜鉛焼鉱を製造する粗酸化亜鉛焼鉱の方法であって、
前記原料を還元焙焼して粗酸化亜鉛ダストを得る還元焙焼工程と、
前記粗酸化亜鉛ダストに湿式処理を施し、水溶性不純物を除去して、粗酸化亜鉛ケーキを得る湿式工程と、
前記粗酸化亜鉛ケーキを乾燥加熱炉で焼成し、粗酸化亜鉛焼鉱を得る乾燥加熱工程と、
前記乾燥加熱工程で発生した排ガスから、水銀を含有する排ガスダストを分離し、更に、前記排ガスダストを、水銀を含有する排ガスダストスラリーとして回収する排ガス処理工程と、を備え、
前記排ガス処理工程で得られる前記排ガスダストスラリーを、所定の水分率となるように乾燥させる水分率調整処理によって排ガスダスト澱物とし、該排ガスダスト澱物を、定量切り出し装置を用いて、前記乾燥加熱工程を行う前記乾燥加熱炉に装入する、粗酸化亜鉛焼鉱の製造方法。
A crude zinc oxide burnt ore method for producing crude zinc oxide burnt ore from a raw material containing zinc, the method comprising:
a reduction roasting step of reducing and roasting the raw material to obtain crude zinc oxide dust;
Wet processing of the crude zinc oxide dust to remove water-soluble impurities to obtain a crude zinc oxide cake;
a drying and heating step of baking the crude zinc oxide cake in a drying heating furnace to obtain crude zinc oxide burnt ore;
An exhaust gas treatment step of separating mercury-containing exhaust gas dust from the exhaust gas generated in the drying and heating step, and further recovering the exhaust gas dust as a mercury-containing exhaust gas dust slurry,
The exhaust gas dust slurry obtained in the exhaust gas treatment step is dried to a predetermined moisture content to form an exhaust gas dust precipitate through a moisture content adjustment process, and the exhaust gas dust slurry is subjected to the drying process using a quantitative cutting device. A method for producing crude zinc oxide sintered ore, which is charged into the drying and heating furnace for performing a heating step.
前記排ガスダストスラリーの水分率が60%を超えていて、
前記排ガスダスト澱物の水分率が20%以上60%以下の範囲内で定められた一定の水分率である、
請求項1に記載の粗酸化亜鉛焼鉱の製造方法。
The moisture content of the exhaust gas dust slurry exceeds 60%,
The moisture content of the exhaust gas dust sediment is a constant moisture content determined within a range of 20% or more and 60% or less,
The method for producing crude zinc oxide burnt ore according to claim 1.
前記排ガスダストスラリーを、天日乾燥により水分率40%超え60%以下まで乾燥させた後、水分率が10%以下の微粉末状の亜鉛含有原料と混合することによって水分率を調整して、水分率40%以下の前記排ガスダスト澱物を得る、
請求項1又は2に記載の粗酸化亜鉛焼鉱の製造方法。
After drying the exhaust gas dust slurry in the sun to a moisture content of more than 40% and less than 60%, the moisture content is adjusted by mixing it with a finely powdered zinc-containing raw material having a moisture content of 10% or less, Obtaining the exhaust gas dust sediment having a moisture content of 40% or less,
The method for producing crude zinc oxide sintered ore according to claim 1 or 2.
前記原料が鉄鋼ダストである、
請求項1又は2に記載の粗酸化亜鉛焼鉱の製造方法。
the raw material is steel dust,
The method for producing crude zinc oxide sintered ore according to claim 1 or 2.
JP2022078775A 2022-05-12 2022-05-12 Method for producing crude zinc oxide sintered ore Pending JP2023167518A (en)

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