Biotechnological recycling of critical metals from waste printed circuit boards

Critical metals are key raw materials for new generation clean energy production. The extraction of critical metals often follows the difficult processing of primary ores and they are many times recovered as the companion metals. With the depletion of primary reserves, the focus has now shifted to processing the urban mines, like electronic (e-)waste. Among the different types of e-waste, the waste printed circuit boards (WPCBs) are the major reservoir of high-value critical metals and are usually treated by the traditional pyro- and/or hydro-metallurgical techniques. However, the application of microbial activities in metals recycling is rapidly emerging as a green technology in comparison to smelter or chemical processing. The application of microorganisms (bacteria/fungi) in WPCBs’ recycling is being increasingly explored in order to meet the parallel objectives of resource recovery and pollution mitigation. Therefore, the present article assesses the current frontiers in bioleaching of critical metals from WPCBs and contains discussions on process fundamentals, challenges, and perspectives. The applicability of microbial recycling of WPCBs at a higher scale in terms of a circular economy and urban mining notion, the techno-economic analysis, and environmental sustainability in comparison to the chemical processing route are also discussed. © 2020 Society of Chemical Industry     

鸡西矿区发展循环经济模式框架构建的探讨

根据《中华人民共和国循环经济促进法》的要求，结合鸡西矿区实际情况，探讨了鸡西矿区发展循环经济模式的框架构建，以便于对当地及煤炭产区开展循环经济建设起到借鉴作用。     

Rohstoff-Recycling und Energie-Gewinnung von Kunststoffabfällen

Feedstock Recycling and Energy Recovery from Plastics Waste. The disposal concept of the plastics industry comprises the following four steps: prevention/reduction, recycling of material (mechanical recycling, feedstock recycling), energy recovery and dumping. Feedstock recycling or chemical recycling stands for the chemical conversion of polymer materials with reduction of macromolecular structure to low-molecular raw materials. The combustion of plastics waste uses the high calorific value of plastics for energy recovery. This paper describes some of the processes for feedstock recycling and for energy recovery from plastics waste.     

Methanol findet zu wenig Beachtung als Kraftstoff und Chemierohstoff der Zukunft

Energy sources in the future are a vividly discussed topic and many statements have been published recently by scientific societies and organizations. However, in most cases an overall view on the topic energy, fuels, raw materials and climate is missing and only little attention is given to the recycling of CO₂ – the use as a raw material, e.g., for the synthesis of methanol whereas emphasis is on carbon capture and storage.     

硫化镍矿中镍提取技术研究进展

作为一种战略金属,镍广泛应用于不锈钢、特殊金属合金、二次电池等领域。近年来,随着新能源汽车产业的快速发展以及动力电池正极材料“无钴高镍”发展趋势,对镍的需求量持续攀升。然而,我国镍资源的对外依存度高达86%,供需矛盾日益突出。针对镍冶炼主要原料的硫化镍矿开采、富集较为困难,传统冶炼方法存在回收率低、环境风险高等瓶颈问题,本研究在分析硫化镍矿矿物学特性的基础上,系统综述了硫化镍矿中镍提取技术的研究进展及存在的问题,综合考虑镍的回收率、物质和能量消耗、环境影响等因素,提出了强化硫化镍矿中镍提取技术研发的建议,同时对硫化镍矿中镍提取技术发展趋势进行了展望。     

Comparative study on the flavonoids extraction rate and antioxidant activity of onions treated by three different drying methods

Onions, rich in flavonoids, with antioxidant, antibacterial, and other biological activities, are often used as extraction of raw materials to obtain health products with high flavonoids content. However, the amount of raw material consumption is large due to low yield of extracts from fresh onions. As a result, dried onions often are used as extraction materials. The effects of air drying (AD), freeze-drying (FD), and microwave freeze-drying (MFD) on the flavonoids extraction yield of onions were investigated. The most effective and economical method was hot AD. On the other hand, the flavonoids extraction rate of onions dried by MFD was the fastest. FD could also obtain high extraction rate, but it cost the highest energy consumption. In order to obtain relatively rapid, economic, and effective extraction of onion flavonoids, onions can be dried by MFD or AD method.     

The carbon footprint and energy consumption of a commercially produced earthenware ceramic piece

The product carbon footprint quantifies the greenhouse gas (GHG) emissions during the life cycle of a product, from the extraction of raw materials, through the production, use and recycling, to the disposal of the used product.In this study, the carbon footprint of an ornamental earthenware ceramic piece has been estimated following the PAS 2050:2011 methodology, and the energy and GHG hotspots have been identified.The carbon footprint and the total energy consumption of the selected ceramic piece is 1.22 kg CO₂e per piece and 8.19 kWh, respectively.The manufacture represents almost 90% of the carbon footprint of the piece.The energy hotspots are natural gas production, biscuit firing and condensing boiler. Some measures to reduce the consumption of natural gas and electricity have been applied, such as the implementation of a gas pressure control system in the kilns and the mill lighting system optimization, respectively.     

盐酸法钛白扮生产工艺

盐酸法钛白粉生产工艺主要包括酸解、还原、结晶、萃取、水解、煅烧、破碎及盐酸回收等。该生产工艺具有原料适应性强、能耗低、“三废”排放量少、盐酸可循环利用等优点。氯碱企业利用副产盐酸生产钛白粉,可产生较好的经济效益和社会效益,是值得氯碱企业开发的项目。     

铜矿尾矿资源化利用研究进展

铜矿开采造成大量尾矿的堆积,在堆积过程中,尾矿不仅占用土地空间,同时还会通过扬尘、渗滤等方式造成大气、地下水的污染,给生态环境带来了巨大压力,对铜矿尾矿的有效处理处置显得迫在眉睫。铜矿尾矿内含有丰富的有用成分,表现出明显的资源特征,资源化利用潜力巨大。本文简要概述了目前国内外有关铜矿尾矿资源化利用的主要思路和技术方法,主要介绍了采用浮选、生物浸出等方法对尾矿中有价组分的再选回收和作为水泥、混凝土掺料及生产砖等建材原料的建筑材料利用,同时指出以铜矿尾矿制备高附加值产品,如作为硅源材料的合成原料生产白炭黑等,可以作为铜矿尾矿精细资源化利用的一条新道路而成为值得关注的发展方向,以期为铜矿尾矿的资源化利用提供参考。     

硫酸法钛白粉生产技术面临循环经济促进法存在的问题与解决办法

硫酸法钛白粉生产技术,在循环经济促进法颁布施行的形势下存在诸多问题,如钛利用率低、硫酸消耗高、废副产品红石膏和硫酸亚铁产量太大难以处置、产品质量低等.针对上述问题,依据循环经济理念,提出了相应的解决办法:1)优化原料,提高钛的利用率;2)采用先进的废酸浓缩回用技术,降低硫酸的消耗;3)将红石膏转化为优良的建筑材料;4)将七水硫酸亚铁按用途、市场半径、地域特点分别利用;5)优化产品结构,提高产品质量.     

目前我国发展循环经济的问题及建议——日照生态工业园规划案例研究

对照循环经济要求分析了当前日照生态工业园规划实施存在的问题并提出几点建议。     

Preparation of tabular corundum aggregate from different sources alumina raw powder: Sintering kinetics and establishment of kinetics model

In this paper, we report the use of four types of commercial alumina raw powders as raw materials for the preparation of tabular corundum aggregates under the same conditions. The influence of the transition phases of alumina raw powder on the sintering kinetics of tabular corundum is discussed, the sintering model of materials with pseudomorphic structure is established, and the mechanisms underlying the different performances of various commercial tabular corundum samples are evaluated. The following conclusions were drawn based on the results of the study. (1) A double tetrakaidecahedron model was established and was shown to satisfactorily describes the sintering mechanism of alumina raw powder with pseudomorphic structure, which accords with the porosity change trend of sintered body and provides a basis for perfecting the sintering theory. (2) Compared with the other transition phases, γ-Al₂O₃ shows the largest phase transformation volume contraction, which provides the driving force for the sintering process via an increase in surface energy and mainly acts in the densification and grain growth stages. Thus, high-quality refractory raw materials are prepared with optimized physical properties and Intracrystalline pores or pore clusters in the crystal structure. The preparation of these high-quality refractory products is of importance for prolonging the life of these materials and also meeting rising energy demands.     

Möglichkeiten zur Wasserstoff-Erzeugung mit verminderter Kohlendioxid-Emission für zukünftige Energiesysteme

Hydrogen production possibilities for future energy systems with reduced carbon dioxide emission. All possible hydrogen production methods which are of technical importance or could become technically important have been systematically classified. The conventional processes based on fossil raw materials, as well as hydrogen production from biomass, are considered with a view to the separation of CO₂ or the minimization of CO₂ emission by using nuclear energy or solar energy, or by using electric energy generated from these primary energies. In addition, possibilities of hydrogen production with carbon separation are investigated. The nonfossil processes using thermal, electric or radiation energy are treated briefly, and water electrolysis is described in more detail. Finally, the hydrogenation of fossil raw materials is discussed, which would lead to mixed carbon-hydrogen energy systems.     

Study of the electronic structure of carbon materials near the bandgap using electron energy loss spectroscopy

The detailed understanding of the electronic properties of semiconducting materials requires the determination of their joint density of states (JDOS) and dielectric constant with high spatial resolution. Low electron energy loss spectroscopy (EELS) provides a continuous spectrum which represents all electronic excitations with energies ranging between zero and about 100 eV. Therefore EELS is potentially more powerful than conventional optical spectroscopy which has an intrinsic upper information limit of about 6 eV due to absorption of light from the optical components of the system or the ambient. However, when analysing EELS data, the extraction of the single scattered data needed for Kramers–Kronig calculations is subject to the deconvolution of the zero loss peak from the raw data. This procedure is particularly critical when attempting to study the near-bandgap region of materials with a bandgap below 1.5 eV. In this paper calculation of the electronic properties of some widely studied carbon materials; namely amorphous carbon (a-C), tetrahedral amorphous carbon (ta-C), C₆₀ fullerite crystal as well as synthetic and natural diamond, are presented. Extrapolation of a fit to the absorption data at the onset of an interband transition was used to get an accurate value for the bandgap energy and to determine whether the bandgap is direct or indirect in character. Particular problems relating to the extraction of the single scattered data for these materials are also discussed. The ta-C and C₆₀ fullerite materials are found to be direct bandgap-like semiconductors, having a bandgap of 2.63 and 1.59 eV, respectively. On the other hand, the electronic structure of a-C was unobtainable because it had such a small bandgap that most of the information is contained in the first 1.2 eV of the spectrum, which is a region removed during the zero loss peak deconvolution. The processing of the data obtained from the ta-C material revealed another benefit of using EELS: the electrons of the beam can transfer momentum and energy to the electrons of the material, thus enabling the probing of indirect interband transitions. Use of this extra feature of EELS coupled with the extremely high spatial resolution obtainable in a scanning electron microscope has indicated that tetrahedral carbon thin films might not be amorphous after all, implying the need for a fresh look at their use as electronic materials.     

中国塑料工业发展动向

比较了中国与世界主要国家合成树脂(塑料原料)生产量、消费量和人均消费量,至2002年其分别列世界第2、第3和第30位;又比较了中国合成树脂消费量、生产量和GDP增长率变化,预测今后在汽车、建筑、包装等产业的支撑下,消费量和生产量还将继续高于GDP的增长趋势。另外,介绍了近年中国塑料制品的进出口概况,分析了原材料涨价给行业带来的问题,提出了依靠技术进步,节能降耗,开发利用可再生材料及加强消费后塑料回收再利用等解决措施。     

Untersuchungen zur Extraktion ölhaltiger Rohstoffe I Theoretisches Modell eines Gegenstrom-Extrakteurs

Investigations of the Extraction of Oil Containing Raw Materials I: The Theoretical Model of a Countercurrent Extractor Pressing and extraction of oil containing raw materials belong to the processes of fat technology with high demands on energy. To obtain the fats from raw materials of high oil content seems to be an interesting solution from this point of view. For an objective valuation of the trials or a semi technical solution it is necessary to explain the countercurrent extraction mathematically. In the present work a model is suggested basing on the balance equation in the final form log (1-E) = -0.4343 B.t, where constant B characterizes single variable dimensions.     

An Overview of Plastics Recycling

In 1980, plastic in the United States has overtaken steel on a volume basis as the dominant material. Though recycling of iron and steel goes back to the early years of United States history, plastics recycling is in its infancy. Today, plastics recycling is an urgent necessity as petrochemical raw materials, energy, and disposal become more costly.     

轮胎生产过程中能源及动力的循环与代用

轮胎生产中各能源动力是除原材料外最大的生产成本。本文介绍了轮胎工厂中水、压缩空气、蒸汽、电等能源动力的循环使用与代用,列举了这几项能源动力代用的节能效果。     

Integrated utilization of high alumina fly ash for synthesis of foam glass ceramic

Due to the numerous increase of the building energy consumption and huge volume of industrial wastes produced in China, the development of thermal insulation materials is quite needed. Herein, foam glass ceramic, a kind of thermal insulation materials, was fabricated by using solid wastes high alumina fly ash and waste glass as the main raw materials. First, in this study the proportion scheme of this research was designed by using Factsage 7.1 and the foaming agent was CaSO₄. Secondly, the decomposition of calcium sulfate and the influence of process parameters, namely the sintering temperature and the foaming agent additive amount, on the microstructure and mechanical properties of foam glass ceramic were investigated. The experimental results showed that when the proposed foam glass ceramic was sintered at between 1180 and 1220?°C, it exerted excellent macro and micro properties. The optimum parameters were 2% CaSO₄ addition and sintering temperature of 1200?°C, and the corresponding bulk density and compress strength values were 0.98?g/cm³ and 9.84?MPa, respectively. Overall these results indicated that the preparation of foam glass ceramic made up a promising strategy for recycling industrial waste into new kind of building insulation materials.     

Research on extraction of Cr(III) by D2EHPA/n-octanol/sulphonated kerosene

Chromium is an important industrial raw material. As far as China is concerned, chromium is in great demand, which is dependent on imports and large emissions. So recovery of chromium has important economic and environmental protection value. The extraction and back extraction of Cr(III) from solution by the extractant diisooctyl phosphate (di-2-ethylhexylphosphoric acid [D2EHPA]) with n-octanol as assistant and sulphonated kerosene as diluent was studied. The effects of saponification rate, phase ratio, temperature, condensation of extract, aging of extractant, and pH of aqueous phase on extraction equilibrium were discussed, and the formulation of extractant was optimized. The coordination number of the extraction reaction under specific conditions was discussed by the saturation capacity method. The extraction reaction kinetics were mathematically characterized by binary linear regression. The advantages and disadvantages of back extraction with H₂SO₄ or NaOH were compared. At last, a process to realize the recycling of extractant was obtained.