Cable Waste Research Articles

Recovery of copper and aluminium from coaxial cable wastes using comparative mechanical processes analysis

ABSTRACT This work aims to perform a comparative study of two mechanical processes for the recycling of metals from coaxial cables (aluminium and copper-clad steel): Process I – comminution, sieving and electrostatic separation; and Process II – comminution, magnetic separation and electrostatic separation. Characterization techniques were performed on the cables to discover their composition. The parameters evaluated of electrostatic separation were: roll speed (n), electrostatic electrode distance (D2), voltage applied to the electrodes (U) and splitter angle (γ). The best conditions for electrostatic separation were: Process I – n = 30 rpm, D2 = 8 cm, U = 30 kV and γ = 0°; Process II – n = 10 rpm, D2 = 10 cm, U = 25 kV and γ = 2.5°. Process I presented aluminium with purity of 99.51% and recovery efficiency of 94.53%, as well as copper-clad steel with purity of 96.79% and recovery efficiency of 99.68%. Process II presented aluminium with purity of 96.51% and recovery of 70.12%, as well as copper-clad steel with purity of 99.53% and recovery of 99.46%. A simplified economic assessment was performed on both process, and Process I has demonstrated to be the most profitable for coaxial cable recycling. The results showed that Process I is promising for the recovery of metals from cables due to its simplicity and lower cost, being capable of wide application to other processes that contain a mixture of conductive and non-conductive particles.

Analysis of the improved water-resistant properties of plaster compounds with the addition of plastic waste

The aim of this article is to analyse the water-resistant properties of gypsum compounds with plastic cable waste added in order to determine the suitability of their use as an alternative to combat moisture problems in buildings. In the experimental process, test samples were made and subjected to capillary water absorption, water vapour permeability, wet chamber, water-stove cycle and total water absorption tests, and their porosimetry was also studied using the mercury porosimetry test. The results showed a significant decrease in water absorption and retention capacity. This is due in part to the reduced pore volume of the compounds that is achieved without affecting the hygrothermal properties of the gypsum products and keeping their mechanical properties above the minimum values indicated in the regulations. Thus, the material studied is a good alternative to the gypsums currently available on the market to be applied in the areas of buildings most exposed to water and it contributes to reduce environmental impacts.

Method of resource saving of cable production recycables

The article discusses development of recycling technologies of cabling and wiring products with justification for the relevance of the cable waste use in the process as part of the closed technological cycle of cabling and wiring products manufacture. Sources of waste generation are analysed. Issues of uninterrupted operation and reliability of technological equipment, efficiency of the recycling process and problems of the development of processing technologies in cable production are highlighted.

Thermal and Mechanical Properties of Blends Containing PP and Recycled XLPE Cable Waste

Recycled XLPE from cable manufacturing waste and end-of-life cables were mixed with virgin polypropylene (PP) in order to evaluate the potential to be used in new injection molded products. The influence of metal contaminations on the mechanical and thermal properties and how the blends could be stabilized in order to be recycled and give reliable properties over time were studied. The results show that blends of 25–50% XLPE in PP give good mechanical properties with retained or improved impact strength independent of the source of XLPE. Ageing at 105 °C for 6 months showed a more severe material degradation and loss of mechanical properties for blends that contained XLPE with end-of-life cable. Addition of metal deactivator proved to retain the mechanical properties for more than 8 months of ageing at 105 °C. Simulated recycling of 50% XLPE in PP stabilized with a metal deactivator, showed that mechanical properties were preserved.

Separation of Copper from Electric Cable Waste Based on Mineral Processing Methods: A Case Study

Recycling of electrical cable waste requires a separation between the metal and the insulating material. The objective of this work was to separate the copper from the plastic in electrical cable waste previously ground below 2 mm, using jigging, shaking table and froth flotation techniques. The effect of particle size was also analysed. Jigging and shaking table proved to be effective in the separation of copper from plastics. The result was a copper concentrate with a copper grade of about 97% by both methods and a copper recovery of about 97%. Jigging separation had similar separation efficiencies in the seven-sized fractions, but in shaking table, the separation efficiency improved with an increase in particles size. The separation achieved by froth flotation had lower efficiencies (85%), because plastics are naturally hydrophobic and copper presents some hydrophobic behaviour. In this technique, the addition of depressant agents was mandatory for the depression of copper, even at low concentrations. The best results were obtained with concentrations of 10−1 mg/L of sodium sulfide (407410 Sigma-Aldrich, Sigma-Aldrich Corporation, St. Louis, MO, USA) and meso-2,3-Dimercaptosuccinic acid (D7881 Sigma-Aldrich).

Validation of a deplasticizer–ball milling method for separating Cu and PVC from thin electric cables: A simulation and experimental approach

There is increasing demand in the electronics recycling industry for an effective method to separate polyvinyl chloride (PVC) and Cu from thin electric cable waste. Herein, a novel separation technique involving PVC embrittlement via plasticizer extraction and crushing by ball milling is proposed. The method was developed by varying the size, quantity, and hardness of the cables, as well as the size and quantity of the milling balls, to determine a combination that resulted in complete separation of PVC and high-purity Cu (>99.9%) from thin electric cables. The experimental crushing behavior was demonstrated via a sphere-to-cylinder discrete element model combined with a statistical approach. The mechanism of PVC crushing generated cracks from the edge to the center of the cable via ball impacts that were strong enough to overcome the elastic repulsion force of the PVC. The resulting method was found to be effective at separating PVC and high-purity Cu (>99.9%) from de-plasticized thin electric cables with diameters of 1.5–2.7 mm.

Separation of metal and plastic wastes from wire and cable manufacturing for effective recycling

The trend to recycle materials in industry has increased over the last few years as manufacturers seek ways to decrease material costs and reduce their environmental footprints. In the wire and cable manufacturing industry, excess wire and cable is shredded into a mixture commonly known as fluff. Because fluff is comprised of different metals as well as polymers of varying physical and chemical properties, it cannot be recycled into a usable product until the different components comprising fluff have been separated. Metallic components could possibly be used for recovery of metals from zinc-carbon and alkaline spent batteries. However, the amount of metals in fluff is low from the economical point of view. Polymeric components might be used in the production of aggregate in concrete – considered for this application together with fly ash. We have employed different concentrations and combinations of frothers, wetting agents, and inorganic materials, encouraging the separation of the different components of fluff by taking advantage of each component’s physical properties. An essential stage of the operation was separating metals from polymers. Among polymers, the main component of fluff was PVC – that we successfully reclaimed and then verified our results through the use of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Success in this endeavor would spell dramatic reductions in unrecyclable wire and cable waste, increase reclamation of materials, and further improve our understanding of the pros and cons of different density-based separation methods.

Analysis of the feasibility of the use of CDW as a low-environmental-impact aggregate in conglomerates

This article summarises the first phase of a research project that analyses the feasibility of re-using plastic cable waste (pellets) as a means of reducing the environmental impact of buildings. The aim is to find a use for this plastic waste in construction materials, specifically gypsum matrices, by characterising the physical and chemical properties of the raw material and the physical and mechanical properties of the compounds. The results obtained show that the addition of up to 70% of the weight of the gypsum in aggregate improved some of the properties tested, such as surface hardness and capillary absorption, and significantly reduced the use of gypsum and water.

Recycling of polymeric fraction of cable waste by rotational moulding

This study focuses on the mechanical recycling of polymeric waste that is produced in considerable amount from the cable industry. Every year large amounts of cables become waste; wires recycling has traditionally focused on metal recovery, while the polymer cover has just been considered as a residue, being landfilled or incinerated. Nowadays, increasingly restrictive regulations and concern about environment make necessary to reduce landfilling as much as possible. Main novelty of the study is that the material used in the research is a post-consumer material and the entire residual material is used, without a previous purification, in contrast with similar studies. Characterization of this residue was performed by thermal analysis, showing that the material is mainly made up of a heavy fraction (84% of the residue), which is not able to melt, fact what makes recycling more difficult. Once characterized, the material was ground, blended with virgin polyethylene and reprocessed by rotational moulding. The influence of the amount of residue and parts structure (1, 2 and 3 layers) was assessed, studying the mechanical behaviour of obtained parts (tensile, flexural and impact properties). It has been found that although mechanical properties get reduced with the increased amount of residue, up to a 35% of residue can be used without an important decrease in mechanical properties. On the other hand, the use of multiple layers in the mouldings allowed obtaining a better external appearance without compromising the mechanical properties.

New separation method of metal/plastic micronized particles using travelling wave conveyors

The paper reports an experimental investigation for studying the movement dynamics and the separation of micronized particles on a poly-phase travelling wave conveyor (TWC). A digital balance and a sensitive electrometer controlled by Labview software were used to analyse the velocity and the material flow rate on a three-phase conveyor with respect to the variation of both the amplitude and the frequency of the applied voltage. It was found that about 80% of the particles mass move together in one single wave and that the electric charge gained by the particles increases with the intensity of the electric field. Moreover, preliminary experiments showed that it is possible to separate a granular mixture of plastic and copper micronized particles using a TWC. Successful experiments were carried out on micronized samples of both electric cable and electronic card wastes. High purity metal was recovered.

Preparation of Poly (vinyl chloride) / Poly(methyl methacrylate) Recycled Blends: Effect of Varied Concentration of PVC and PMMA in Stability of PVC Phase on the Recycled Blends

The present work deals with the effective utilization of plastics generated from E-waste stream. Polyvinyl chloride (PVC) collected from the data cable waste and Poly(methyl methacrylate) (PMMA) waste materials from the light guidance panels used in the LED screens of computers are used as raw materials in the present investigation. Recycled blend of PVC/PMMA was prepared using mechanical recycling techniques at different compositions via melt blending techniques. The blends were characterized by mechanical, thermal, and morphological studies. The molecular interactions that have taken place between the polymeric materials in the recycled blend have been evaluated using FTIR analysis. The flammability characteristics of the blends were studied by determining rate of burning. The miscibility characteristics in the blends have been studied scanning electron microscopy. Overall stability of the recycled blend improved as compared with its parent recycled materials..

Product design for cable waste peeler machine

The design of the cable waste peeler is a product design that aims to reduce the impact of health losses. In general, this is due to the activity of taking the metal in a cable that is done by burning the cable. The design process begins with the identification of customer needs. The customer referred to in this study is the informal sector. Based on interviews that have conducted on several respondents obtained four primary needs that must be illustrated in product design. Then, to explain the four needs are available three types of design variants. The results showed weighting measurements and calculations on load values of approximately 4.15 for the second variant. The results of these calculations are higher than the other two types of design variants. Thus, the design of the variant is chosen for the next design process.

Experimental and Numerical Study of the Electrostatic Separation of Two Types of Copper Wires From Electric Cable Wastes

Electrostatic separators are not commonly used for the selective sorting of different sorts of metals contained in a granular mixture. However, the separation might be possible if their characteristics (density, conductivity, size, etc.) are different enough. The aim of this paper is to evaluate the feasibility of sorting tinned and bare copper strands (length: 2–5 mm; diameter: 0.8–1.6 mm) contained in granular electric cable wastes using a roll-type electrostatic separator with three different high-voltage electrode configurations: plate; S-shaped; and reverse S-shaped. Experimental design methodology is used to investigate the effects of three factors: 1) high voltage applied to the electrode; 2) system, inclination of the high-voltage electrode; and 3) interelectrode distance. The recovery and purity of the bare copper product are evaluated for each experiment. The best results of the electrostatic separation experiments are obtained with the reversed S-shaped electrode configuration (recovery of 55.4% of the bare copper wire in a product having a copper content of 85.1%). Numerical modeling and experimental visualization of particle trajectories facilitate the interpretation of the electrostatic separation experimental results.

Optimization of metals and plastics recovery from electric cable wastes using a plate-type electrostatic separator

Plate-type electrostatic separators are commonly employed for the selective sorting of conductive and non-conductive granular materials. The aim of this work is to identify the optimal operating conditions of such equipment, when employed for separating copper and plastics from either flexible or rigid electric wire wastes. The experiments are performed according to the response surface methodology, on samples composed of either “calibrated” particles, obtained by manually cutting of electric wires at a predefined length (4mm), or actual machine-grinded scraps, characterized by a relatively-wide size distribution (1–4mm). The results point out the effect of particle size and shape on the effectiveness of the electrostatic separation. Different optimal operating conditions are found for flexible and rigid wires. A separate processing of the two classes of wire wastes is recommended.

Optimal Operation of a Plate-Type Corona-Electrostatic Separator for the Recovery of Metals and Plastics from Granular Wastes

Plate-type electrostatic separators are commonly employed for the selective sorting of conductive and nonconductive granular materials. Unfortunately, the purity of the conductive products is often compromised by the fact that the trajectories of the nonconductive granules cannot be controlled. The aim of the present work is to validate a relative simple solution to this problem: subjecting the granules to a corona discharge during their sliding down the plate electrode. This discharge does not affect the conductive granules but charges the nonconductive ones, so that the electric force would tend to pin them to the surface of the grounded electrode. In this way, the friction forces between the granules and the plate increase and the inertia forces decrease. Design of experiments methodology is employed to identify the optimum high-voltage, relative position of the electrodes, and configuration of the collector. The conclusions of this study served at the optimum design of an industrial corona-assisted plate-type electrostatic separator for the recycling of metals and plastics from granular electric cable wastes.

Simulation of cable and wire waste separation process

Growth in the amount of waste containing non-ferrous metals leads to environmental pollution. Waste recycling is economically advantageous not only from an environmental standpoint. The problem is to separate the scrap components for further processing. The cheapest method is gravity separation in the air stream. The study found that the process efficiency and performance depend on the material looseness in the working space of the separator. The effect of this parameter is examined through numerical simulation using the discrete element method and GranularLux software package. This method allows exploring various process parameters in very small, discrete time periods, the impact of which is difficult to reveal in the field experiment. The theoretical basis of the method and the results of simulation of cable and wire waste separation process are presented. It is shown that simulation allows determining the rational looseness of scrap particles in the working space of the separator, which provides the required quality of separation products. The results can be used in the development of technology and equipment for waste separation into components. Waste recycling will reduce human impacts on the environment.

Multivariate Control for Three Variables of an Industrial Roll-Type Electrostatic Separator

Hotelling's $T^{2}$ charts have already proven their effectiveness in the multivariate control of electrostatic separation process. The aim of this work is to extend the use of these charts from two to three variables, in order to improve the statistical control of an industrial roll-type electrostatic separator designed for the recycling industry. In the case of electrostatic separation processes, the use of Hotelling's $T^{2}$ chart for three variables would allow controlling on a single graph the correlation between the masses accumulated in the three boxes of the product collector. The results of the study carried out on a pilot-plant electrostatic separator for metals and insulators from electric cable wastes in Algeria demonstrated the effectiveness of such a chart in detecting out-of-control situations: accumulation of dust particles on the high-voltage electrodes and reduction of the input flow of raw materials.

Recovery of copper from PVC multiwire cable waste by steam gasification

Screened multiwire, PVC insulated tinned copper cable was gasified with steam at high temperature (HTSG) under atmospheric pressure for recovery of cooper. Gases from the process were additionally equilibrated at 850°C on the bed of calcined clay granules and more than 98% of C+H content in the cable was transformed to non-condensing species. Granules prepared from local clay were generally resistant for chlorination, there was also almost no deposition of metals, Cu and Sn, on the catalytic bed. It was found that 28% of chlorine reacted to form CaCl2, 71% was retained in aqueous condensate and only 0.6% was absorbed in alkaline scrubber. More than 99% of calcium existed in the process solid residue as a mixture of calcium chloride and calcium oxide/hydroxide. PVC and other hydrocarbon constituents were completely removed from the cable sample. Copper was preserved in original form and volatilization of copper species appeared insignificant. Tin was alloying with copper and its volatilization was less than 1%. Fractionation and speciation of metals, chlorine and calcium were discussed on the basis of equilibrium model calculated with HSC Chemistry software. High temperature steam gasification prevents direct use of the air and steam/water is in the process simultaneously gaseous carrier and reagent, which may be recycled together with hydrocarbon condensates.

EFFECT OF MILLED ELECTRICAL CABLE WASTE ON MECHANICAL PROPERTIES OF CONCRETE

The article focuses on investigation of mechanical and fracture properties of concrete containing electrical cable waste as well as some microstructural features of such concrete. Added to concrete, electrical cable waste reduces the overall concrete bulk density. Compressive, flexural, tensile splitting strengths and elastic modulus decreased when electrical cable waste was admixed to conventional and polymer modified concretes. The best mechanical properties of concrete samples containing electrical cable waste were identified in polymer modified concrete containing 5% of electrical cable waste. Electrical cable waste particles increase the deformability of polymer modified concretes and have almost no influence on normal concrete. Consequently, the optimal amount of electrical cable waste particles can provide concrete with desirable strength that is required for different applications.

Separation of Covering Plastics from Particulate Copper in Cable Wastes by Induction Electrostatic Separation

Separation of Covering Plastics from Particulate Copper in Cable Wastes by Induction Electrostatic Separation