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High Efficiency Recovery of Valuable Metals from Ceramics Scraps by Hydrothermal Mechanochemical Method

水热机械化学法从陶瓷废料中高效回收有价金属

基本信息

批准号：
16360326
负责人：
ITOH Hideaki
金额：
$ 8.96万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

项目摘要

In this project, we carried out the following experiments and obtained the following results :Hydrothermal extraction process of Co binder phase from WC-Co cermet was investigated in order to establish a novel recycling system of WC-Co cermet scraps. When the cermet chips were hydrothermally treated in hydrochloric acid above 110℃, Co binding phase was efficiently extracted and the cermet chips were disintegrated into relatively large fragments. After hydrothermal treatment, WC sintered body became very brittle and pulverized easily by ball milling and the mean particle size of thus obtained WC particle became similar to that of virginal WC particle. The recycled WC powder was a little easier to undergo oxidation than the virginal WC powder, so that the mechanical properties of recycled WC-Co cermet were degraded. However, the degradation of mechanical properties was prevented only by drying the WC powder more carefully. This hydrothermal process will be one of the recycling systems fo … More r WC-Co cermet.The WC-Co cermet specimens with various WC particle sizes and Co content were hydrothermally treated in HNO_3 aqueous solutions at temperatures of 110-200℃ for duration of 6-240h. The Co was preferentially leached out into the acidic solution, while the WC was oxidized to insoluble WO_3 hydrate which was subsequently separated by filtration. The hydrothermal treatment parameters such as solvent concentrations, treatment temperatures, holding time were optimized in respect to different kinds of WC-Co cermets. A hydrothermal oxidation treatment in 3M HNO_3 aqueous solution at 150℃ for 24h was capable of fully disintegrating the cermet chip composed of coarse WC grains of 1-5 〓m in size with 20 mass% of Co as binder. While the more oxidation resistant specimen composed of fine WC grains of 0.5-1.0 〓m in size with 13 mass% of Co, was completely disintegrated by a treatment in 7M HNO_3 aqueous solution at 170℃ for 24h. The filtered solid residues were composed of fine WO_3・0.33H_2O powder and a small amount of WO_3. The recovered WO_3・0.33H_2O powder can be easily returned to the industrial process for the synthesis of WC powder so that the overall recycling cost can be possibly lowered.The hydrothermal treatment of used Nd-Fe-B sintered permanent magnet was investigated in order to recover the rare-earth resources efficiently. Commercially available Ni-coated Nd_2Fe_<14>B sintered magnet was hydrothermally treated under the optimum conditions at 110℃ for 6h in the mixed aqueous solution of hydrochloric acid (3.0mol/dm^3) and oxalic acid (0.2mol/dm^3). As a result, more than 99% of Nd metal contained in the magnet was collected as solid precipitate of Nd_2(C_2O_4)3・xH_2O with the purity as high as 99.8%. Less

在本项目中，我们进行了以下实验并取得了以下成果：研究了WC-Co金属陶瓷中Co粘结相的水热提取工艺，以建立一种新型的WC-Co金属陶瓷废料回收系统。当金属陶瓷切片在110℃以上的盐酸中进行水热处理时，Co结合相被有效萃取，金属陶瓷切片被分解成较大的碎片。水热处理后，WC烧结体变得非常脆，很容易通过球磨粉碎，由此获得的WC颗粒的平均粒径变得与原始WC颗粒的平均粒径相似。回收的WC粉末比原始WC粉末更容易发生氧化，从而导致回收的WC-Co金属陶瓷的机械性能下降。然而，只有通过更仔细地干燥 WC 粉末才能防止机械性能的下降。该水热工艺将成为WC-Co金属陶瓷的回收系统之一。将不同WC粒径和Co含量的WC-Co金属陶瓷试样在HNO_3水溶液中于110-200℃的温度下进行水热处理6-240h。 Co优先浸出到酸性溶液中，而WC被氧化成不溶性的WO_3水合物，随后通过过滤分离。针对不同种类的WC-Co金属陶瓷，优化了溶剂浓度、处理温度、保温时间等水热处理参数。以20质量%的Co为粘结剂，在3M HNO_3水溶液中150℃水热氧化处理24h，能够使尺寸为1~5〓m的粗WC晶粒组成的金属陶瓷切片充分崩解。而由尺寸为0.5-1.0〓m的细WC颗粒和13质量%的Co组成的更抗氧化的样品，在170℃的7M HNO_3水溶液中处理24h后完全崩解。过滤后的固体残渣由细小的WO_3·0.33H_2O粉末和少量的WO_3组成。回收的WO_3·0.33H_2O粉末可以很容易地返回到WC粉末合成的工业过程中，从而可以降低总体回收成本。为了有效回收稀土资源，对废Nd-Fe-B烧结永磁体的水热处理进行了研究。将市售Ni包覆Nd_2Fe_<14>B烧结磁体在盐酸(3.0mol/dm^3)和草酸(0.2mol/dm^3)混合水溶液中在最佳条件下于110℃水热处理6h。结果，磁体中99%以上的Nd金属以Nd_2(C_2O_4)3·xH_2O固体沉淀形式被收集，纯度高达99.8%。较少的