利用无胶热压成型技术的新型制管机设计及其工艺参数确定

设计了一种适用于生产的新型环保连续热压塑化制管机。该机器以农产品加工废弃植物原材料(茶渣、花生秸秆等)为原料,利用无胶热压成型技术,制成可替代传统纸管的新型热压塑化管。研制的机器经过反复研究与试验,结果表明:在实际生产中,该机器可实现连续化生产且生产过程无废水、废料、废气,实现无三废生产;纤维管生产速度可达7.2 m/h;产品抗压强度可达2 000 N以上;相对于市面纸管的生产,该机器大大降低了能源损耗和人工成本,具有广阔的市场前景,以及较好的社会效益和经济价值。     

Ceramic wastes as alternative raw materials for Portland cement clinker production

The cement industry has for some time been seeking procedures that would effectively reduce the high energy and environmental costs of cement manufacture. One such procedure is the use of alternative materials as partial replacements for fuel, raw materials or even clinker. The present study explores the reactivity and burnability of cement raw mixes containing fired red or white ceramic wall tile wastes and combinations of the two as alternative raw materials.The results showed that the new raw mixes containing this kind of waste to be technically viable, and to have higher reactivity and burnability than a conventional mix, providing that the particle size of the waste used is lower than 90 μm. The mineralogical composition and distribution in the experimental clinker prepared were comparable to the properties of the clinker manufactured with conventional raw materials. Due to the presence of oxides such as ZnO, ZrO₂ and B₂O₃ in tile glazing, the content of these oxides was higher in clinker made with such waste. The mix of red and white ceramic wall tile waste was found to perform equally or better than each type of waste separately, a promising indication that separation of the two would be unnecessary for the purpose described above.     

Utilization of flotation wastes of copper slag as raw material in cement production

Copper slag wastes, even if treated via processes such as flotation for metal recovery, still contain heavy metals with hazardous properties posing environmental risks for disposal. This study reports the potential use of flotation waste of a copper slag (FWCS) as iron source in the production of Portland cement clinker. The FWCS appears a suitable raw material as iron source containing >59% Fe(2)O(3) mainly in the form of fayalite (Fe(2)SiO(4)) and magnetite (Fe(3)O(4)). The clinker products obtained using the FWCS from the industrial scale trial operations over a 4-month period were characterised for the conformity of its chemical composition and the physico-mechanical performance of the resultant cement products was evaluated. The data collected for the clinker products produced using an iron ore, which is currently used as the cement raw material were also included for comparison. The results have shown that the chemical compositions of all the clinker products including those of FWCS are typical of a Portland cement clinker. The mechanical performance of the standard mortars prepared from the FWCS clinkers were found to be similar to those from the iron ore clinkers with the desired specifications for the industrial cements e.g. CEM I type cements. Furthermore, the leachability tests (TCLP and SPLP) have revealed that the mortar samples obtained from the FWCS clinkers present no environmental problems while the FWCS could act as the potential source of heavy metal contamination. These findings suggest that flotation wastes of copper slag (FWCS) can be readily utilised as cement raw material due to its availability in large quantities at low cost with the further significant benefits for waste management/environmental practices of the FWCS and the reduced production and processing costs for cement raw materials.     

Utilization of municipal solid waste incineration ash in Portland cement clinker

Municipal solid waste incineration (MSWI) ash is used in part as raw materials for cement clinker production by taking advantage of the high contents of SiO₂, Al₂O₃, and CaO. It is necessary for environmental reasons to establish a material utilization system for the incineration waste ash residue instead of disposing these ashes into landfill. The aim of this paper is to study the feasibility of replacing clinker raw materials by waste ash residue for cement clinker production. MSWI bottom ash and MSWI fly ash are the main types of ashes being evaluated. The ashes were mixed into raw mixture with different portions of ash residue to produce cement clinker in a laboratory furnace at approximately 1400°C. X-ray diffraction and X-ray florescence techniques were used to analyze the phase chemistry and chemical composition of clinkers in order to compare these ash-based clinkers with commercial Portland cement clinker.     

Recycling of waste printed circuit boards: a review of current technologies and treatment status in China

From the use of renewable resources and environmental protection viewpoints, recycling of waste printed circuit boards (PCBs) receives wide concerns as the amounts of scrap PCBs increases dramatically. However, treatment for waste PCBs is a challenge due to the fact that PCBs are diverse and complex in terms of materials and components makeup as well as the original equipment's manufacturing processes. Recycle technology for waste PCBs in China is still immature. Previous studies focused on metals recovery, but resource utilization for nonmetals and further separation of the mixed metals are relatively fewer. Therefore, it is urgent to develop a proper recycle technology for waste PCBs. In this paper, current status of waste PCBs treatment in China was introduced, and several recycle technologies were analyzed. Some advices against the existing problems during recycling process were presented. Based on circular economy concept in China and complete recycling and resource utilization for all materials, a new environmental-friendly integrated recycling process with no pollution and high efficiency for waste PCBs was provided and discussed in detail.     

Valorisation of chicken feathers: a review on recycling and recovery route—current status and future prospects

Worldwide, the poultry meat processing industry generates large quantities of feather by-products that amount to 40 × 10⁹ kg annually. The feathers are considered wastes although small amounts are often processed into valuable products such as feather meal and fertilisers. The remaining waste is disposed of by incineration or by burial in controlled landfills. Improper disposal of these biological wastes contributes to environmental damage and transmission of diseases. Economic pressures, environmental pressures, increasing interest in using renewable and sustainable raw materials, and the need to decrease reliance on non-renewable petroleum resources behove the industry to find better ways of dealing with waste feathers. A closer look at the structure and composition of feathers shows that the whole part of a chicken feather (rachis and barb) can be used as a source of a pure structural protein called keratin which can be exploited for conversion into a number of high-value bioproducts. Additionally, several technologies can be used to convert other biological components of feathers into high value-added products. Thus, conversion of the waste into valuable products can make feathers an attractive raw material for the production of bioproducts. In this review, possible applications of chicken feathers in a variety of technologies and products are discussed. Thus, using waste feathers as a valuable resource can help the poultry industry to dispose of the waste feathers in an environmentally sustainable manner that also generates extra income for the industry. Their valorisation can result in their sustainable conversion into high-value materials and products on the proviso of existence or development of cost-effective technologies for converting this waste into the useful products.     

Comparative life cycle assessment of beneficial applications for scrap tires

Life cycle assessment is used to determine the most environmentally beneficial alternatives for reuse of scrap tires, based on the concept of industrial ecology. Unutilized scrap tires can be a major source of pollution, and in the past decade Federal and state governments in the United States have encouraged the recycling and reuse of scrap tires in a number of applications, ranging from energy recovery to civil engineering materials to utilization of ground rubber in manufacturing. Life cycle inventory data are collected from primary industry sources as well as published literature, and life cycle impact analysis is performed using the TRACI tool. The results indicate that beneficial reuse of scrap tires, particularly in cement plants and artificial turf, provides reductions in greenhouse gas (GHG) emissions, air toxics, and water consumption. For example, every metric ton of tire-derived fuel substituted for coal in cement kilns avoids an estimated 543 kg (CO₂ equivalent) of direct and indirect GHG emissions. Taking into account the deductible CO₂ from natural rubber, the avoided GHG emissions would be 613 CO₂ kg eq. per metric ton. The use of scrap tires for fuel in cement plants provides more reductions in most environmental impact categories compared to other scrap tire applications, excluding application in artificial turf. Although the use of ground rubber for artificial turf offers the greatest environmental emission reductions, it has limited potential for large-scale utilization due to the saturated market for artificial turf. Therefore, the use of fuel derived from scrap tires in cement production appears to be an attractive option in view of its large market capacity and significant potential for environmental impact reductions.     

Predicting porosity content in triaxial porcelain bodies as a function of raw materials contents

This work describes the relationships observed between the porosity of fired ceramic test pieces and the raw materials contents in the unfired mixture. The investigation was carried out using the mixture experiments design approach coupled with response surface methodology, which enables the calculation of statistically significant models for the properties from a limited number of experimental results. Ten formulations of a clay mixture, potash feldspar and quartz sand were processed in the laboratory under fixed conditions, similar to those used on wall and floor tile industrial practice, and characterized. Closed porosity (CP) was estimated from the analysis of back-scattered SEM photomicrographs, open porosity (OP) was calculated as the product of bulk density and water absorption, and total porosity (TP) was calculated from OP and CP values. Characterization results were used to calculate statistically significant and valid regression equations, relating those properties with the raw material contents in the unfired mixture. For the particular raw materials and processing conditions used, the models clearly show how quartz contributes to increasing OP and the crucial role played by feldspar when CP and TP are to be minimized (circa 3 vol.%), and how the clay content can counteract that effect and lead to maximum closed porosity (∼14 vol.%).     

Scrap tire-beer bottle concrete

A set of experiments are described where the fundamental uniaxial tension and compression properties of an asphaltic concrete composed of scrap tires, crushed beer bottles, and asphalt were determined using constant strain rate tests. The analyses included statistical evaluations and approximations of the moduli, compliances, and times to failure for other types of loading. Over 5 decades of strain rate testing, the ultimate stress varied between 7 and 530 psi and the ultimate strain varied between 2.8 and 0.34 percent, where the compression properties were a half-order greater than the tension properties. Optimization of the mixture reported and then field implementation by street construction would not only provide a potential means for recycling all waste glass and scrap tires, this would also provide a means for constructing a superior pavement for less cost. Increased elongation or strain in the pavement could be achieved due to the rubber, and decreased thermal stress due to environmental conditions would result because of the low coefficient of thermal expansion for glass.     

Synthesis and Characterization of Iron-Rich Glass Ceramic Materials:A Model for Steel Industry Waste Reuse

Wastes deriving from steel industry, containing large amounts of iron oxides and heavy metals, when collected in landfills are subjected to atmospheric agents, with consequent release of toxic substances in the soil and groundwater. The reuse of these wastes as raw materials for the production of advanced materials is a viable way both to overcome the environmental impact and to reduce the disposal costs,proposing new technologically advanced materials. This work aims to simulate these interesting glassceramics by using glass cullet coming from recycled municipal waste and high amount of iron(III) oxide(from 25 wt% to 50 wt%), the prevalent component of steel waste. The oxide was mixed with glass cullet and vitrified. The samples composition and the microstructure were investigated by scanning electron microscopy(SEM), and X-ray diffraction(XRD) was used to evaluate the nature of the crystalline phases.The chemical stability of the materials, in terms of ionic release into saline solution, was assessed. The electrical behavior of the samples was also investigated by varying the iron ions content and controlling the crystallization process. It is possible to obtain chemically stable materials with a nearly semiconducting behavior.