WO2014040332A1 - 一种从含铅废弃电子垃圾阴极射线管玻璃中回收利用铅的方法 - Google Patents

一种从含铅废弃电子垃圾阴极射线管玻璃中回收利用铅的方法 Download PDF

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WO2014040332A1
WO2014040332A1 PCT/CN2012/083052 CN2012083052W WO2014040332A1 WO 2014040332 A1 WO2014040332 A1 WO 2014040332A1 CN 2012083052 W CN2012083052 W CN 2012083052W WO 2014040332 A1 WO2014040332 A1 WO 2014040332A1
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lead
glass
crt
ray tube
powder
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PCT/CN2012/083052
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English (en)
French (fr)
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刘承帅
路星雯
施凯闵
李芳柏
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广东省生态环境与土壤研究所
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Priority to US14/428,517 priority Critical patent/US9650693B2/en
Publication of WO2014040332A1 publication Critical patent/WO2014040332A1/zh

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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B13/00Obtaining lead
    • C22B13/02Obtaining lead by dry processes
    • C22B13/025Recovery from waste materials
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00Preliminary treatment of ores or scrap
    • C22B1/14Agglomerating; Briquetting; Binding; Granulating
    • C22B1/24Binding; Briquetting ; Granulating
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B7/00Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
    • C22B7/001Dry processes
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00Technologies related to metal processing
    • Y02P10/20Recycling

Definitions

  • the invention belongs to the field of hazardous waste disposal and resource utilization, and particularly relates to a method for recycling lead from a lead-containing waste electronic cathode ray tube glass. Background technique:
  • Cathode Ray Tube is the earliest and most widely used display technology equipment in industrial production. It has the advantages of mature technology, high reliability and long service life. It has long been used as an electronic device such as televisions, computer monitors and oscilloscopes. The main display device. At present, the number of existing TV sets in China exceeds 400 million, the vast majority of which are CRT TVs, and the number of computer CRT monitors has exceeded 40 million. With the rapid development of electronic display device technology, liquid crystal displays have severely impacted the market share of CRT displays with their unique advantages, resulting in a year-on-year increase in the amount of CRT displays. China has developed into a major producer and consumer of electronic products, and a large number of electronic products have reached the peak of phase-out.
  • Waste CRT Containing lead CRT glass is a hazardous waste and has become the focus of e-waste disposal. At present, some countries or regions still use landfill as the main way to dispose of used CRT glass. However, as the CRT glass goes through the landfill time, the heavy metal lead in the used CRT glass will dissolve out and enter the underground water, which will cause serious damage to the ecological environment and human health.
  • the US Environmental Protection Agency wrote in a report that 98.7% of metal lead in municipal solid waste comes from e-waste, and 29.8% of it comes from spent CRT glass. In 2000, Stephen et al. conducted a leaching toxicity test on lead in spent CRT cone glass using the solid waste TCLP toxicity leaching standard procedure recommended by the US Environmental Protection Agency.
  • CRT glass is a kind of resource solid waste that cannot be ignored. It is estimated that the weight of CRT glass being used nationwide is about 6 million tons, of which the total lead content is about 8.3%, reaching 500,000 tons.
  • the raw material for lead smelting is mainly lead sulphide ore, and the grade of ore produced is generally less than 3%.
  • the ore dressing is lead refined and re-smelted, while the lead grade in color CRT cone glass is about 20 wt.%.
  • the dip method was to dissolve 0.5 g of CRT glass powder into 75 ml of a 3 mol/L nitric acid solution and heat to 95 °C for 2 hours to achieve a lead ion recovery of only 1.2%.
  • the method of heat treatment for extracting metallic lead has been extensively studied, including carbon thermal vacuum reduction, thermal reduction of SiC and TiN, and high temperature self-propagation evaporation.
  • the carbon thermal vacuum thermal reduction method requires carbon powder as a reducing agent to extract metal lead from the vitreous at a temperature of 1000 ° [at a low vacuum of 10-100 Pa for at least 4 hours. Due to the relatively high heat treatment temperature and vacuum requirements, this method is difficult to perform in large-scale industrial applications. Relatively speaking, the temperature required to thermally reduce metallic lead from CRT glass powders with SiC and TiN is lower (about 850 °C), but the extraction rate is also lower ( ⁇ 40%), and the reduction method is used. Reducing agents (SiC and TiN) are expensive.
  • the self-propagating high-temperature evaporation method is used to recover metal lead.
  • metal Mg spontaneously reacts with Fe 2 0 3 to provide heat for self-propagation.
  • the saturated vapor pressure of the metal lead reaches the point where the lead can evaporate, the metal lead evaporates from the vitreous.
  • the temperature required for this method is around 2000 °C, and the cost of extracting metal lead with metal Mg is also high.
  • the technical method of recycling lead from leaded CRT glass waste has always required higher energy consumption to destroy the lead-doped 3-D glass structure and further extract metal lead.
  • the lead content in CRT cone glass is higher than that of lead ore, but the main difficulty is the lack of an effective technique for extracting lead from reticular silicate structure glass. It has been found in the current literature that the technique of extracting lead generally requires higher energy, expensive chemicals or complicated extraction processes. In general, the metal lead is extracted from the Si0 2 mesh glass structure and the temperature required is higher than 1000.
  • the object of the present invention is to provide a method for recycling lead from lead-containing waste electronic waste cathode ray tube glass with low cost, resource recycling and high recovery rate for the currently produced lead-containing CRT electronic waste.
  • the invention changes the glass structure around the lead in the glass during the heat treatment by mixing a certain amount of zero-valent iron in the lead-containing CRT glass powder, thereby extracting metal lead at a lower temperature and preventing the metal lead from re-entering the glass matrix.
  • the object of the present invention is achieved.
  • the method for recycling lead from a lead-containing waste electronic waste cathode ray tube glass includes the following steps: taking a lead-ray glass containing a cathode ray tube as a sample, pulverizing the CRT glass powder, and then The zero-valent iron powder and the CRT glass powder are uniformly mixed at a mass ratio of 0.1 to 1.5:1, and kept at 610 to 960 °C for 3 to 180 minutes, and then cooled, and the metal lead is extracted from the Si0 2 mesh glass structure of the CRT glass. come out.
  • the cathode ray tube containing the lead cone glass is taken as a sample, and the CRT glass powder is crushed to the CRT cone-screen bonding portion, and the cathode ray tube containing the lead cone glass is taken, and the particle diameter is broken. After ⁇ 3 cm, it is further pulverized by a planetary ball mill to a particle size of less than 65 mesh, and dried at 105 ° C for 24 h to obtain a CRT glass powder, which is ready for use.
  • the temperature is preferably 610 to 910 ° C, and the holding time is preferably 15 to 45 minutes.
  • the glass transition temperature (T g ) of the lead-containing waste electronic waste cathode ray tube glass is 505 ° C
  • the lead-containing waste electronic waste cathode ray tube glass becomes a highly viscous liquid.
  • the zero-valent iron and the extracted metal lead are surrounded by a viscous glass liquid, preventing the oxygen in the air from further reacting with the metal iron and lead during the heat treatment.
  • the crystallization process described is as shown in the formula (1):
  • the present invention utilizes that when the heat treatment temperature is higher than Tg , the lead-containing CRT glass becomes a highly viscous liquid, and the zero-valent iron and the extracted metal lead are surrounded by the viscous glass liquid, suppressing oxygen in the air. Reacts with metal iron and lead during heat treatment to prevent lead from returning to the glass matrix and improve lead recovery.
  • the invention adopts a sample input method, and directly inputs a mixture of lead-containing CRT glass and zero-valent iron into an environment of 610 to 960 ° C which has been heated up, thereby preventing the iron of the reducing agent from being in the air during the process of heating up the furnace.
  • the oxygen protects the reduction properties of zero-valent iron.
  • the invention has no toxic and no gas generated during the heat treatment process, and does not pollute the atmosphere.
  • the reducing agent involved is zero-valent iron, environmentally friendly material, and relatively cheap, and does not cause secondary pollution during use and is suitable. Mass promotion.
  • the method for recycling lead from the lead-containing waste electronic waste cathode ray tube glass of the present invention is carried out under normal pressure, and the required temperature is low, the process is simple, the operation is simple, and the scale production is easy.
  • the present invention can be applied to pretreatment of lead-containing waste CRT glass, and metal lead is extracted from the network silicate structure of lead-containing waste CRT glass by heat treatment process of adding zero-valent iron, thereby effectively improving electronic waste.
  • the disposal rate of materials and the protection of ecological security have important environmental, social and economic significance, and have broad application prospects.
  • Figure 1 is the effect of the weight ratio of zero-valent iron powder/lead CRT glass powder on the lead extraction rate of metal at 710 ° C and holding time of 30 minutes;
  • Figure 2 is at 610. C, 710. C and 960. C three-temperature, zero-valent iron powder / lead CRT glass powder When the weight ratio is 1/1, the effect of different heat treatment time of 3-180 minutes on the metal lead extraction rate. detailed description:
  • the method for recycling lead from a lead-containing waste electronic waste cathode ray tube glass of the present invention comprises the following steps:
  • Lead-containing waste electronic waste cathode ray tube glass is a waste color display cone glass with a lead content of about 20 wt.% .
  • the zero-valent iron powder used as a reducing agent has a purity of more than 99% and a particle diameter of less than 80 mesh. Zero-valent iron powder is first sealed and ready to use.
  • the zero-valent iron powder and the CRT glass powder are weighed according to the mass ratio of 0.1 to 1.5:1, and the ball mill is uniformly mixed.
  • the mixed powder was pressed into a cylindrical cake having a diameter of 20 mm and a thickness of 5 mm at a temperature of 650 MPa at room temperature to ensure a tight bond between the powders during heating, which was advantageous for the heat treatment reaction.
  • Corundum is also placed in an oven at 105 °C for use.
  • the weighed cylindrical cake was placed in a corundum crucible and weighed again.
  • the muffle furnace is heated to 610 to 960 ° C, preferably 610 to 910 ° C.
  • the corundum crucible containing the cylindrical cake is put into a muffle furnace for heat treatment reaction, and the reaction time is 3 to 180 minutes. Preferably, it is 15-45 minutes.
  • the reaction time reaches the target time, immediately remove the crucible with insulated gloves and fire tongs, and let it cool in the air to room temperature.
  • the metal lead in the cylindrical cake can be purified by conventional beneficiation methods such as flotation or chemical leaching to obtain elemental metal lead.
  • Example 1 Effect of heat treatment temperature on lead extraction efficiency
  • a cylindrical cake of a mixture of zero-valent iron powder and lead-containing CRT glass powder having a mass ratio of 0.1:1 and 1.5:1 was heated at 500 to 960 ° C (see Table 1 for details) for 30 minutes.
  • iron does not interact with lead-containing glass, and only iron is oxidized by oxygen in the air.
  • 610 °C the formation of a metallic lead phase was first observed.
  • the signal of the metallic lead phase increases significantly.
  • the thermal reduction reaction of extracting lead from lead-containing glass with zero-valent iron as a reducing agent can be achieved, as described in formula (1):
  • the effects of the addition of zero-valent iron powder on lead extraction efficiency were investigated at temperatures of 610 °C, 710 °C and 960 °C and heat treatment for 30 minutes.
  • the lead content was quantitatively analyzed by X-ray, and the lead extraction rate was effectively increased as the content of zero-valent iron in the sample increased.
  • the mass ratio of zero-valent iron powder/lead CRT glass powder is 1/1 reduced metal lead, the metal lead extraction rate is maximized.
  • This example examines the effect of heat treatment time on lead extraction efficiency.
  • Zero-valent iron powder/lead-containing CRT glass powder is made into a cylindrical cake with a mass ratio of 1/1, and then at 610. C, 710. C and 960.
  • three heat treatments were carried out for different times at 3-180 minutes, and the results are shown in Fig. 2.
  • the metal lead extraction ratio was increased to 35% by a long heat treatment of 180 minutes.
  • the lead extraction rate and the heat treatment time showed a significant proportional relationship.
  • the lead extraction rate decreased to 35%.
  • the lead extraction efficiency is inversely proportional to the heat treatment retention time. The extraction rate of crystal lead rapidly reaches 25% within 3 minutes, and the lead extraction efficiency decreases during the heat treatment time.

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Abstract

本发明公开了一种从含铅废弃电子垃圾阴极射线管玻璃中回收利用铅的方法。它取有阴极射线管含铅锥玻璃作为样品,将其粉碎得CRT玻璃粉末,然后将零价铁粉与CRT玻璃粉末按照质量比0.1~1.5:1混合均匀,在610~960°C中保温3~180分钟,再经冷却,金属铅从CRT玻璃的SiO2网状玻璃结构中提取出来。本发明可应用于对含铅废CRT玻璃进行预处理,通过添加零价铁的热处理过程,从含铅废旧CRT玻璃的网状硅酸盐结构中提取金属铅,从而有效的提高电子废弃物的处置率和保障生态安全,具有重要的环境、社会和经济意义,应用前景广泛。

Description

一种从含铅废弃电子垃圾阴极射线管玻璃中回收利用铅的方法 技术领域:
本发明属于危险废物处置及资源化利用领域,具体涉及一种从含铅废弃电子 垃圾阴极射线管玻璃中回收利用铅的方法。 背景技术:
阴极射线管 (Cathode Ray Tube, CRT)是工业化生产最早、应用最广泛的显示 技术设备,具有技术成熟、可靠性高、使用寿命长等优点, 长期以来作为电视机、 计算机显示器以及示波器等电子设备的主要显示设备。 目前, 我国现有电视机的 社会保有量超过 4亿台, 其中绝大多数为 CRT电视机, 计算机 CRT显示器的保有 量也已超过 4000万台。随着电子显示设备技术的快速发展, 液晶显示器以其独特 优越性严重地冲击了 CRT显示器的市场占有额, 导致 CRT显示器废弃量逐年递 增。 我国已经发展成为电子产品的生产、 消费大国, 大量电子产品已到了淘汰报 废的高峰期。 从 2009年 6月 1日我国家电产品"以旧换新"政策推广实施, 截止到 2010年 5月底, 共计回收废弃电子电器产品约 1500万台, 其中 CRT电视机约占 82%。 全国 28个试点省市共回收约 1200万台显示器, 几乎全部是 CRT显示器。
废弃 CRT中含铅 CRT玻璃属于危险废物, 已成为电子废物处理关注的重点。 目前, 部分国家或地区仍将填埋作为处理处置废旧 CRT玻璃主要方式。 但随着 CRT玻璃在填埋场时间的推移,废旧 CRT玻璃中重金属铅将会溶出从而进入地下 水,将会对生态环境和人体健康带来严重危害。美国环境保护署曾在一份报告中 写道,城市固体废物中 98.7%金属铅来源于电子废物,其中 29.8%就来自于废 CRT 玻璃。 Stephen等人在 2000年采用美国环境保护署推荐的固废 TCLP毒性浸出标准 程序对废旧 CRT锥玻璃中的铅进行了浸出毒性实验, 结果发现, CRT锥玻璃中的 铅浸出浓度平均值约为 75.3mg/L, 远远超出了危险废物鉴别标准。 因此, 如何处 置并利用数量庞大的废旧 CRT显示器,已成为我国乃至世界环境保护领域所面临 的一大挑战。
同时, CRT玻璃是一种不可忽视的资源性固体废物。据估算, 全国正在使用 的 CRT玻璃重量约 600万吨, 其中总含铅量约 8.3%, 达到 50万吨。 在目前在冶炼 行业中, 炼铅的原料主要是硫化铅矿, 采出的矿石品位一般低于 3%, 而且须经 选矿得到铅精矿再行冶炼, 而彩色 CRT锥玻璃中铅品位为 20 wt.%左右。
综合考虑资源、 环境、 技术、 经济等多方面因素, 对废旧含铅 CRT玻璃实 行资源化再利用是较为合理的处置方式。 目前, 国际上针对废弃 CRT玻璃进行 铅提取处理方法的研究主要集中于以下四类: ① 酸、碱溶液浸泡洗涤; ② 热处 理提取金属铅; ③ 机械萃取; ④ 热处理、 清洗、 浸泡等步骤混合法。 其中酸、 碱溶液浸泡洗涤方法提取铅的效率相对较低。 根据 2012 年在 Envi丽羅 tal Science & Technology (46 卷, 页码: 4109-4114)期刊上发表的题为 "Innovated Application of Mechanical Activation to Separate Lead from Scrap Cathode Ray Tube Funnel Glass"的文章,通过添加强酸浸洗方法,溶解 0.5克的 CRT玻璃粉末到 75 毫升 3摩尔 /升的硝酸溶液中并加热到 95 °C持续 2个小时,所达到的铅离子回收 率仅为 1.2 %。
热处理提取金属铅的方法被大量的研究过, 包括炭热真空还原、 SiC和 TiN 热还原和高温自蔓延蒸发处理这三种方法。炭热真空热还原方法需要用炭粉作为 还原剂在 1000 °〔的温度, 低真空 10-100Pa下, 用至少长达 4个小时的热处理 过程来把金属铅从玻璃体中提取出来。 由于比较高的热处理温度和真空度要求, 导致这种方法很难进行大规模的工业应用。 相对来说, 用 SiC和 TiN从 CRT玻 璃粉末中热还原金属铅所需要的温度较低(约 850 °C), 但是提取率也较低(<40 %), 而且这种还原方法中采用的还原剂(SiC和 TiN) 昂贵。 采用自蔓延高温蒸 发方法回收利用金属铅, 是超高温度下, 金属 Mg会自发的与 Fe203反应来提供 热量, 用于进行自蔓延过程。 当金属铅的饱和蒸汽压达到铅能蒸发时, 金属铅从 玻璃体中蒸发出来。 一般来说, 这种方法所需要的温度在 2000 °C左右, 而且用 金属 Mg来提取金属铅成本也较高。
用 Na2EDTA作为萃取剂的机械萃取方法需要较长的萃取时间 (20 h) 以及 较高比例萃取剂 Na2EDTA的消耗。 另外一种被报导的方法是用硫元素来硫化机 械活化含铅 CRT玻璃粉末, 但是没有报道金属铅硫化率, 而且该方法的最后产 物是 PbS而不是金属铅。
一直以来, 从含铅 CRT玻璃废物中回收利用铅的技术方法都需要较高的能 耗, 以此来破坏镶嵌铅的 3-D玻璃结构, 从而进一步提取金属铅。这是因为铅原 子被包含在 Pb03多面体的结构里面, 而且这种多面体又被 Si04四面体牢牢的密 封住, 形成了致密的网状玻璃结构。 CRT 锥玻璃中的铅含量高于铅矿石, 但主 要困难是缺乏一个行之有效的技术从网状硅酸盐结构玻璃中提取出铅。在目前的 文献中发现, 萃取铅的技术通常需求较高能量, 昂贵的化学用品或者复杂的提取 过程。 一般来说, 要把金属铅从 Si02网状玻璃结构中提取出来, 所需的温度都 高于 1000。C。 发明内容:
本发明的目的是针对目前大量产生的含铅 CRT电子废弃物, 提供一种低成 本、资源再生利用、高回收率的从含铅废弃电子垃圾阴极射线管玻璃中回收利用 铅的方法。
本发明通过在含铅 CRT玻璃粉末中混入一定量的零价铁, 在热处理过程中 改变玻璃中铅周围的玻璃结构, 实现在较低的温度下提取金属铅, 并防止金属铅 重新进入玻璃基质, 从而实现了本发明的目的。
本发明的从含铅废弃电子垃圾阴极射线管玻璃中回收利用铅的方法,其特征 在于, 包括以下步骤: 取有阴极射线管含铅锥玻璃作为样品, 将其粉碎得 CRT 玻璃粉末, 然后将零价铁粉与 CRT玻璃粉末按照质量比 0.1〜1.5: 1混合均匀, 在 610〜960 °C中保温 3〜180分钟,再经冷却,金属铅从 CRT玻璃的 Si02网状玻 璃结构中提取出来。
所述的取有阴极射线管含铅锥玻璃作为样品, 将其粉碎得 CRT玻璃粉末是 对 CRT的锥屏结合部位进行破碎, 取有阴极射线管含铅锥玻璃, 将其破碎至粒 径 1〜3 cm后,用行星式球磨机进一步粉碎至粒径小于 65目,于 105 °C干燥 24 h, 得 CRT玻璃粉末, 待用。
所述的温度优选为 610〜910°C, 所述的保温时间优选为 15〜45分钟。
由于含铅废弃电子垃圾阴极射线管玻璃的玻璃化转变温度 (Tg) 为 505 °C, 当热处理温度高于 Tg时, 含铅废弃电子垃圾阴极射线管玻璃变成高度粘稠液体。 零价铁与提取出的金属铅被粘稠的玻璃液体包围,防止了空气中氧气与金属铁和 铅在热处理过程中进一步反应, 所描述的结晶过程如式 (1 ) 所示:
≡Si-O Pb+ + Fe(0)→ Pb(0) + Fe+ O-Si≡ (1) 因此,温度太低不利于金属铅的提取, 而温度太高和热处理时间太长则会导 致提取出的金属铅会返回到玻璃基质。对于金属铅的提取, 最优化的实验条件为 零价铁粉与 CRT玻璃粉末按照质量比 1.5: 1混合均匀, 然后在 710°C中保温 30 分钟, 在此条件下最多可以从阴极射线管玻璃 -Si02网状玻璃中还原出 60%的铅 单质, 与在同类型的含铅 CRT玻璃中提取金属铅的热处理方法相比, 所用温度 最低, 且所需时间最短的。
与现有技术中从含铅 CRT玻璃中提取金属铅的技术相比, 本发明具有以下 优点:
1. 本发明利用了当热处理温度高于 Tg时, 含铅 CRT玻璃会变成高粘稠液 体, 零价铁和被提取出的金属铅被粘稠的玻璃液体包围, 抑制了空气中 氧气与金属铁和铅在热处理过程中的反应,防止铅重新回到玻璃基质中, 提高铅的回收率。
2. 本发明采用样品投入法,把含铅 CRT玻璃与零价铁的混合物直接投入到 已经升温的 610〜960 °C环境中,从而防止了还原剂铁在随炉升温的过程 中被空气中的氧气, 保护了零价铁的还原性能。
3. 本发明在热处理过程无有毒无气体产生, 不会对大气造成污染, 所涉及 的还原剂为零价铁, 环境友好材料, 并且相对便宜, 在使用过程中不会 造成二次污染且适合大规模推广。
4. 本发明的从含铅废弃电子垃圾阴极射线管玻璃中回收利用铅的方法, 是 在常压下进行, 并且所需的温度低, 工艺简单, 操作简便, 易于进行规 模化生产。
因此, 本发明可应用于对含铅废 CRT玻璃进行预处理, 通过添加零价铁的 热处理过程, 从含铅废旧 CRT玻璃的网状硅酸盐结构中提取金属铅, 从而有效 的提高电子废弃物的处置率和保障生态安全,具有重要的环境、社会和经济意义, 应用前景广泛。 附图说明:
图 1是在 710°C且保温时间为 30分钟时, 零价铁粉 /含铅 CRT玻璃粉末的重量 比对金属铅提取率的影响;
图 2是在 610。C, 710。C和 960。C三个温度下, 零价铁粉 /含铅 CRT玻璃粉末的 重量比为 1/1时, 3-180分钟的不同热处理时间对金属铅提取率的影响。 具体实施方式:
以下实施例是对本发明的进一步说明, 而不是对本发明的限制。
本发明的从含铅废弃电子垃圾阴极射线管玻璃中回收利用铅的方法,包括以 下步骤:
一、含铅废弃电子垃圾阴极射线管玻璃粉的制备及其与零价铁粉的混合方法 含铅废弃电子垃圾阴极射线管玻璃为含铅量约为 20 wt.%的废旧彩色显示屏 锥玻璃。
(1)对废旧彩色显示屏 CRT的锥屏结合部位进行破碎分离, 取锥部位的含铅 锥玻璃作为样品。 含铅锥部位玻璃的表面涂料则由湿式洗涤法完全去除。
(2)对已经去除表面涂料的含铅锥玻璃进行破碎, 碾碎至粒径约 1〜3 cm后, 用行星式球磨机进行下一步粉碎。
(3)将粉碎后的粉末过 65 目的漏筛, 将筛选出的粉末(< 65目)放置于 105 °〔烘箱中, 并干燥 24 h, 得到 CRT玻璃粉末, 待用。
(4)被用作还原剂的零价铁粉的纯度大于 99 %, 且其粒径小于 80 目。 零价 铁粉先处于密封状态, 随用随取。
(5)零价铁粉与 CRT玻璃粉末按质量比 0.1〜1.5: 1称取,进行球磨混合均匀。
(6)在室温下, 用 650兆帕的压力将混合后的粉末压制成直径为 20mm和厚 度为 5mm的圆柱形饼, 以保证在加热过程中粉末之间结合紧密, 利于热处理反 应。
二、 含铅 CRT玻璃粉末与零价铁粉的混合物的投入式热处理
(1) 将压实的圆柱形饼先置于 105 °C烘箱中待用,对每个要用于热处理的圆 柱形饼称重并记录。
(2) 刚玉坩埚同时也置于 105 °C烘箱中待用。将称重的圆柱形饼置入刚玉坩 埚中, 再一次进行称重。
3) 将马弗炉加热至 610〜960 °C, 优选为 610〜910°C, 稳定后将放有圆柱形 饼的刚玉坩埚投入马弗炉中, 进行热处理反应, 反应时间为 3〜180分钟, 优选为 15-45分钟。 (4) 当反应时间达到目标时间, 立即用带隔热手套结合防火钳取出坩埚, 并 将其置于空气中自然冷却至室温。
(5) 称量已经冷却的圆柱形饼与刚玉坩埚的重量, 并记录。
(6) 破碎刚玉坩埚, 并取出圆柱形饼, 辗成粉末, 对其进行 X-射线和 X-射 线荧光 (XRF) 分析, 分析铅的提取效率。
对于圆柱形饼中的金属铅可通过浮选或化学浸提等常规选矿方法提纯得到 单质金属铅。
实施例 1 : 热处理温度对铅提取效率的影响
参考上述从含铅废弃电子垃圾阴极射线管玻璃中回收利用铅的方法的步骤 进行, 对其中的一些参数进行变化或具体话, 其他相同, 具体如下:
将零价铁粉和含铅 CRT玻璃粉末的质量比为 0.1 : 1和 1.5: 1的混合并压制成 的圆柱形饼, 在 500〜960°C (具体见表 1 ) 中加热 30分钟。 根据其 X射线衍射图谱 得出, 当热处理温度低于 610 °C, 铁与含铅玻璃没有相互作用, 只有铁被空气中 的氧气氧化。在 610 °C, 首先观察到有金属铅相的形成。此外, 随着温度的升高, 金属铅相的信号显著增加。 并在温度为 710 °C时, 获得最高的晶体铅形成率, 用 零价铁作为还原剂从含铅玻璃体中提取铅的热还原反应可以实现, 如式 (1 ) 所 描述的结晶过程:
≡Si-O Pb+ + Fe(0)→ Pb(0) + Fe+ O-Si≡ (1) 随着进一步的温度升高, 金属铅相的信号强度并不随着温度的升高而升高。 这种现象似乎表明, 金属铅相的信号强度急剧降低是由于金属铅的挥发和 /或提 取到金属铅又返回到玻璃基质中而导致的铅的玻璃化。
表 1 : 热处理温度对金属铅相形成的影响
金属铅相形成率%
热处理温度 (°c) 零价铁粉 /含铅 CRT玻璃粉末 零价铁粉 /含铅 CRT玻璃粉末 质量比为 0.1 : 1 质量比为 1.5 : 1
500 0 0
610 4.20 11.74
660 19.66 33.40
710 34.78 50.67
760 28.58 45.08
810 25.80 36.73
860 16.04 23.50
910 5.38 11.92
960 0 8.88
实施例 2: 实验过程中铅蒸发可能性确定
参考上述从含铅废弃电子垃圾阴极射线管玻璃中回收利用铅的方法的步骤 进行, 对其中的一些参数进行变化或具体话, 其他相同, 具体如下:
为了排除实验过程中铅蒸发的可能性, 将零价铁粉与含铅 CRT玻璃粉末的 质量比为 0.1 : 1 的样品称重混合并压制成圆柱形饼再进行热处理, 温度范围为 600-960 °C (具体见表 2) 的热处理。 将热处理后的样品进行称重和 X-射线荧光 (XRF) 检查, 样品反应前后的重量和 XRF数据列于表 2。 并利用样品的重量 和 XRF数据, 计算出的铅的损失, 在所有温度下的铅损失量都小于 1 wt.%。 结 果表明, 起始样品中铅的含量与它在相应热处理后的样品中是一致的。 因此, 这 些发现证实在热处理过程中没有铅的挥发。综合实施例 2中的结果表明, 在热处 理过程中从玻璃结构中所提取的结晶金属铅会随着温度的升高重新进入玻璃基 质中。 本实施例说明, 在热处理过程中, 无铅挥发效应, 不会对大气造成污染。 表 2: 不同温度样品的 XRF结果及铅损失的计算
XRF结果 (wt. %) 里 t (g) 铅损失
¾ 处 ¾¾度 ( C)
PbO Fe203 起始 残余 量 (%)
600 20.69 13.24 3.47 3.48 NDa
650 19.76 13.67 4.21 4.33 NDa
700 19.31 12.25 3.98 4.15 0.38
750 19.26 12.56 4.31 4.62 NDa
800 18.72 13.13 3.68 4.07 NDa
850 18.97 13.79 4.23 4.47 0.78
900 19.86 13.84 3.69 3.84 NDa
960 19.66 13.44 3.87 4.04 NDa 原始 CRT 20.23 12.11 ~ ~ ~ a ND : 无检测值
实施例 3: 零价铁粉添加量对铅提取效率的影响
参考上述从含铅废弃电子垃圾阴极射线管玻璃中回收利用铅的方法的步骤 进行, 对其中的一些参数进行变化或具体话, 其他相同, 具体如下:
为了优化工艺参数, 分别在 610 °C, 710 °C和 960 °C的温度和热处理 30分 钟的条件下, 考察零价铁粉的加入量对铅提取效率的影响。 结果如图 1所示, 通 过 X-射线对铅含量进行定量分析, 铅提取率随零价铁含量在样品中的增加而有 效地提高。此外, 当零价铁粉 /含铅 CRT玻璃粉末的质量比为 1/1还原金属铅时, 金属铅的提取率达到最大。 在 610 °C, 当零价铁粉 /含铅 CRT玻璃粉末的质量比 从 0.1/1增加到 0.75/1时, 铅回收比率从 4%增加至 20%, 在零价铁粉 /含铅 CRT 玻璃粉末的质量比为 0.75/1〜1.5/1的范围,铅提取效率相对稳定一致。在 960 °C, 结果类似, 当零价铁粉 /含铅 CRT玻璃粉末的质量比从 0.1/1增加到 0.75/1时, 铅回收比率从 0%增加至 11%, 然而, 随着零价铁粉 /含铅 CRT玻璃粉末的质量 比进一步不断增加, 铅提取效率没有相应的改变。 在 710 °C时, 当零价铁粉 /含 铅 CRT玻璃粉末的质量比从 0.1/1增加到 1/1 时, 铅的提取率随零价铁粉 /含铅 CRT玻璃粉末的质量比的增加而增加, 即使在零价铁粉 /含铅 CRT玻璃粉末的质 量比增加到 1.5/1, 最高铅提取率稳定在 60%左右, 在回收过程中, 零价铁粉 /含 铅 CRT玻璃粉末的质量比从 1/1增加到 1.5/1 时, 铅提取率仅仅从 58%提升到 60%。 因此, 从经济角度考虑, 推荐用零价铁粉 /含铅 CRT玻璃粉末的质量比为 1/1提取铅。
实施例 4: 热处理时间对铅提取效率的影响
参考上述从含铅废弃电子垃圾阴极射线管玻璃中回收利用铅的方法的步骤 进行, 对其中的一些参数进行变化或具体话, 其他相同, 具体如下:
本实施例考察了热处理时间对铅提取效率的影响。 零价铁粉 /含铅 CRT玻璃 粉末的质量比为 1/1的混合物制成圆柱形饼, 再在 610。C, 710。C和 960。C三个 温度下,分别进行 3-180分钟的不同时间的热处理,其结果如图 2所示。在 610 °C, 通过 180分钟长时间的热处理作用, 金属铅的提取比例提高至 35%。 在温度为 710°C时, 从 3分钟到 30分钟, 铅提取率与热处理时间呈现显着的正比关系, 在热处理保持时间从 30分钟增到 180分钟时, 铅提取率下降至 35%。 在热处理 温度为 960°C时,铅提取效率与热处理保持时间呈反比关系, 结晶铅的提取率在 3分钟内迅速达到 25%, 延长热处理时间铅提取效率下降。
本实施例结果表明, 在热处理过程中, 包含两种机制, 由式 (1 ) 所描述的 铅提取反应, 以及提取出的金属铅被玻璃化到玻璃基质中的反应, 如式 (2): ≡ Si-0-Si≡ + Pb(0)→≡Si-0-Pb+ + -Si≡ (2) 较高的温度和较长的热处理时间将进一步熔化玻璃,使得金属铅被玻璃化到 玻璃基质中, 对从玻璃结构中提取铅有很大的负面作用。最佳的实验条件为, 在 零价铁粉与含铅 CRT玻璃粉末的质量比为 1.5/1, 温度为 710 °C, 热处理 30分 钟。
以上所述仅为本发明的较佳实施例, 并不用以限制本发明, 凡在本发明的精 神和原则之内所做的任何修改、等同替换和改进等, 均应包含在本发明的保护范 围之内。

Claims

权 利 要 求
1、 一种从含铅废弃电子垃圾阴极射线管玻璃中回收利用铅的方法, 其特征 在于, 包括以下步骤: 取有阴极射线管含铅锥玻璃作为样品, 将其粉碎得 CRT 玻璃粉末, 然后将零价铁粉与 CRT玻璃粉末按照质量比 0.1~1.5: 1混合均匀, 在 610~960 °C中保温 3~180分钟,再经冷却,金属铅从 CRT玻璃的 Si02网状玻 璃结构中提取出来。
2、 根据权利要求 1所述的方法, 其特征在于, 所述的取有阴极射线管含铅 锥玻璃作为样品,将其粉碎得 CRT玻璃粉末是对 CRT的锥屏结合部位进行破碎, 取有阴极射线管含铅锥玻璃, 将其破碎至粒径 1~3 cm后, 用行星式球磨机进一 步粉碎至粒径小于 65目, 于 105 °C干燥 24 h, 得 CRT玻璃粉末, 待用。
3、 根据权利要求 1所述的方法, 其特征在于, 所述的温度为 610~910°C。
4、根据权利要求 1或 3所述的方法,其特征在于,所述的保温时间为 15~45 分钟。
5、 根据权利要求 1所述的方法, 其特征在于, 零价铁粉与 CRT玻璃粉末的 质量比为 1.5: 1, 所述的温度为 710°C, 所述的时间为 30分钟。
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