Recovery Of Raw Materials Research Articles

Photovoltaic waste assessment: Forecasting and screening of emerging waste in Australia

Australia has to meet the challenges of End-of-Life treatment of photovoltaic modules in coming years due to rapid growth of photovoltaic capacity during the last decades. This paper contributes towards the sustainable management of decommissioned solar panels through the estimation of PV waste flow between the years 2031–2047 based on the actual installation of the PV modules from 2001 to 2018, and the provision of a forecasting model applying on four major scenarios to project the waste generated from 2048–2060. Assuming three forecasting schemes, and consistent annual-growth-rate of PV installation for each scenario, the future PV waste was quantified. Considering the PV installation from 2001 to 2018, the cumulative waste is estimated to be 0.8 million tonnes until 2047. The mainstream of the waste is estimated to be glass and aluminium with 541,209 and 116,483 tonnes respectively, followed by 8375 tonnes of copper and 71,329 tonnes of steel. The PV waste includes various valuable substances which, if appropriately recycled, can bring significant economic benefit. With regards to all PV penetration scenarios in the electricity generation market until 2030, Australia is estimated to face around 1–8 million tonnes of decommissioned PV until 2060. The recovery of the EoL PV raw materials can lead to value creation of nearly 1.2 billion dollars. These findings can shed light on the possibility of a circular economy and suggest an active contribution of all parties and a very well-planned coordinated approach prevent the potential environmental impacts and maximize resource efficiency.

Scientific and Technical Problems in Natural Gas Recovery, Transport, and Processing

One of the priorities in Russia’s scientific and technological development is the transition to environmentally friendly and sustainable energy and increasing efficiency in the recovery and advanced processing of hydrocarbon raw materials. Realization of this aim will not only create a balanced, stably developing R&D sector in this field, but also ensure competitiveness among companies operating in the global gas market. This necessitates the close cooperation between PJSC Gazprom, the largest transnational energy corporation, and the Russian Academy of Sciences. Back in 2002, the company’s board and the Presidium of the Russian Academy of Sciences adopted the Program of Fundamental and Applied Research of RAS Institutes, within which research teams of the Academy carried out a set of studies on the most important problems in the development of Russia’s gas production. In 2017, the Research and Development Program in the interests of Gazprom was updated and aimed at further development of Russia’s energy and industrial infrastructure, the creation of a fundamental basis for new technologies, and the elaboration and implementation of innovative products and services at gas recovery, transport, and processing facilities.

Valorization of Mining Waste by Application of Innovative Thiosulphate Leaching for Gold Recovery

The metals and industrial minerals contained in the tailings of mining and quarrying activities, can degrade natural environments as well as human health. The objective of this experimental work is the application of innovative and sustainable technologies for the treatment and exploitation of mining tailings from Romania. Within this approach, the recovery of high grade raw materials to be placed on the market is achieved and reduction of these wastes volume are achieved. The current study is focused on hydrometallurgical process for the recovery of gold. The innovative treatment chosen is the thiosulphate process that, compared with the conventional cyanide, has several advantages (e.g., it is more ecologically friendly and is not toxic to humans). The conventional cyanidation process shows operating limits in the case of auriferous refractory minerals, such as Romanian wastes, the object of the study. An important characteristic of thiosulphate leaching process it has the best selectivity towards gold; it does not attack the majority of the gangue mineral constituents. Gold extraction of 75% was obtained under ambient conditions of temperature. Moreover, the overall process achieved about 65–67% Au recovery, this being in line with the conventional cyanidation process. As these results are obtained by application of the thiosulfate process on a low gold content ore, they may be considered encouraging. The optimization of process parameters and operating conditions, should permit the best results in terms of process yields to be achieved.

An assessment of achievements of the WEEE Directive in promoting movement up the waste hierarchy: experiences in the UK

Rapidly developing technology and an increasing number of products containing electrical or electronic functions, has led to discarded electrical and electronic equipment (EEE) being one of the fastest growing waste streams. The European Union (EU) has enacted several iterations of the Waste Electrical and Electronic Equipment (WEEE) Directive to address this complex waste stream. However, recycling dominates treatments for e-waste, despite the established ‘waste hierarchy’ showing waste prevention and reuse are generally preferable to recycling.This paper reports on 30 semi-structured interviews, undertaken across the EEE value chain, examining the impact of the WEEE Directive in the UK. The interviews confirmed that reuse takes place for a limited number of product types, mostly on a small scale. Additionally, whilst legislation has prompted innovation in recycling and higher capture rates, resource recovery is in practice limited to easily salvageable materials, whilst recovery of critical raw materials is often neglected. Furthermore, there is confusion around available collection networks, particularly for small WEEE, which consistently appears in residual waste streams.The waste hierarchy remains the key component of EU waste strategy and moving to the higher levels of the waste hierarchy is an essential part of achieving sustainable waste management and moving towards a circular economy. The paper proposes a series of measures to this end: promoting recovery routes and practices that facilitate reuse of suitable products, adapting recycling technology to increase recovery of critical raw materials and targeted policies to encourage the application of the waste hierarchy within a resource efficiency-oriented framework.

Leaching of rare earth elements (REEs) and impurities from phosphogypsum: A preliminary insight for further recovery of critical raw materials

Phosphogypsum is a pollutant waste generated by the fertilizer industry. Managing this pollutant is challenging due to the large volumes generated worldwide. A promising route is the valorization of phosphogypsum to recover rare earth elements. However, optimized recovery schemes are needed to create a cost-effective and environmentally friendly process. This paper studies the extraction efficiency of rare earth elements from phosphogypsum and the release of impurities during leaching in a variety of solutions and different working conditions. The best leaching performance was obtained using a 3 M nitric acid (above 80%) solution that achieved a dissolution rate of 63% of the gypsum originally present. In contrast, using 0.5 M sulfuric acid extracted between 46% and 58% of the rare earth elements contained in phosphogypsum, dissolving less than 6% of the gypsum. This higher dissolution of gypsum led to a higher release of impurities by nitric acid. Increasing reaction times from 2 h to 8 h yielded an improvement of leaching efficiency of around 8% for both leaching solutions, while also promoting an increase of 6% in the release of impurities. Adding DTPA resulted in poor leaching performance (from 13% to 22%). Pretreating phosphogypsum with water can remove a significant fraction of the impurities without scavenging rare earth elements. Mineralogical and chemical evidence suggests unreacted phosphate and fluoride are the most probable minerals hosting rare earth element minerals in phosphogypsum. The results of this study could contribute to optimizing recovery methods to extract rare earth elements from phosphogypsum worldwide, thus helping achieve the goals of the circular economy.

Recycling Polyethylene-Rich Plastic Waste from Landfill Reclamation: Toward an Enhanced Landfill-Mining Approach.

In the frame of a circular economy, the maximization of secondary raw-material recovery is necessary to increase the economic and environmental sustainability of landfill mining and reclamation activities. In this paper, the polyethylene-rich plastic fraction recovered from the reclamation of an abandoned industrial landfill (landfill-recovered plastic, LRP) has been characterized through spectroscopic, thermal, morphological, and mechanical analyses. Then, an economically viable valorization and recycling strategy was set up. The effectiveness of this strategy in the enhancement of LRP properties has been demonstrated through morphological and mechanical characterizations.

Raw material recovery from hydraulic fracturing residual solid waste with implications for sustainability and radioactive waste disposal.

Unconventional oil and gas residual solid wastes are generally disposed in municipal waste landfills (RCRA Subtitle D), but they contain valuable raw materials such as proppant sands. A novel process for recovering raw materials from hydraulic fracturing residual waste is presented. Specifically, a novel hydroacoustic cavitation system, combined with physical separation devices, can create a distinct stream of highly concentrated sand, and another distinct stream of clay from the residual solid waste by the dispersive energy of cavitation conjoined with ultrasonics, ozone and hydrogen peroxide. This combination cleaned the sand grains, by removing previously aggregated clays and residues from the sand surfaces. When these unit operations were followed by a hydrocyclone and spiral, the solids could be separated by particle size, yielding primarily cleaned sand in one flow stream; clays and fine particles in another; and silts in yet a third stream. Consequently, the separation of particle sizes also affected radium distribution - the sand grains had low radium activities, as lows as 0.207 Bq g-1 (5.6 pCi g-1). In contrast, the clays had elevated radium activities, as high as 1.85-3.7 Bq g-1 (50-100 pCi g-1) - and much of this radium was affiliated with organics and salts that could be separated from the clays. We propose that the reclaimed sand could be reused as hydraulic fracturing proppant. The separation of sand from silt and clay could reduce the volume and radium masses of wastes that are disposed in landfills. This could represent a significant savings to facilities handling oil and gas waste, as much as $100 000-300 000 per year. Disposing the radium-enriched salts and organics downhole will mitigate radium release to the surface. Additionally, the reclaimed sand could have market value, and this could represent as much as a third of the cost savings. Tests that employed the toxicity characteristic leaching protocol (TCLP) on these separated solids streams determined that this novel treatment diminished the risk of radium mobility for the reclaimed sand, clays or disposed material, rendering them better suited for landfilling.

Recycling glass fiber thermoplastic composites from wind turbine blades

Thermoplastic resin systems have long been discussed for use in large-scale composite parts but have yet to be exploited by the energy industry. The use of these resins versus their thermosetting counterparts can potentially introduce cost savings due to non-heated tooling, shorter manufacturing cycle times, and recovery of raw materials from the retired part. Because composite parts have high embedded energy, recovery of their constituent materials can provide substantial economic benefit. This study determines the feasibility of recycling composite wind turbine blade components that are fabricated with glass fiber reinforced Elium® thermoplastic resin. Several experiments are conducted to tabulate important material properties that are relevant to recycling, including thermal degradation, grinding, and dissolution of the polymer matrix to recover the constituent materials. Dissolution, which is a process unique to thermoplastic matrices, allows recovery of both the polymer matrix and full-length glass fibers, which maintain their stiffness (190 N/(mm g)) and strength (160 N/g) through the recovery process. Injection molded regrind material is stiffer (12 GPa compared to 10 GPa) and stronger (150 MPa compared to 84 MPa) than virgin material that had shorter fibers. An economic analysis of the technical data shows that recycling thermoplastic–glass fiber composites via dissolution into their constituent parts is commercially feasible under certain conditions. This analysis concludes that 50% of the glass fiber must be recovered and resold for a price of $0.28/kg. Additionally, 90% of the resin must be recovered and resold at a price of $2.50/kg.

Biotechnological strategies for the recovery of valuable and critical raw materials from waste electrical and electronic equipment (WEEE) - A review.

Critical raw materials (CRMs) are essential in the development of novel high-tech applications. They are essential in sustainable materials and green technologies, including renewable energy, emissionfree electric vehicles and energy-efficient lighting. However, the sustainable supply of CRMs is a major concern. Recycling end-of-life devices is an integral element of the CRMs supply policy of many countries. Waste electrical and electronic equipment (WEEE) is an important secondary source of CRMs. Currently, pyrometallurgical processes are used to recycle metals from WEEE. These processes are deemed imperfect, energy-intensive and non-selective towards CRMs. Biotechnologies are a promising alternative to the current industrial best available technologies (BAT). In this review, we present the current frontiers in CRMs recovery from WEEE using biotechnology, the biochemical fundamentals of these bio-based technologies and discuss recent research and development (R&D) activities. These technologies encompass biologically induced leaching (bioleaching) from various matrices,biomass-induced sorption (biosorption), and bioelectrochemical systems (BES).

Platinized counter-electrodes for dye-sensitised solar cells from waste thermocouples: A case study for resource efficiency, industrial symbiosis and circular economy

A study of a local industrial symbiosis involving the recovery of platinum from waste thermocouples which is then used for the preparation of catalytic electrodes suitable for dye-sensitized solar cell production is reported. The small quantity of platinum in the filaments of used thermocouples, thousands of which are discarded each year by metal foundries, can be economically recovered by conversion to chloroplatinic acid hydrate, an ‘added value’ product, which can then be used in the fabrication of dye-sensitized solar cell counter-electrodes. 91% recovery of platinum from filaments as chloroplatinic acid hydrate has been achieved by aqua regia digestion of manually isolated filaments. Cost-benefit analysis shows the proposed process derives sufficient value to cover landfill costs for what is left of the waste thermocouples after platinum removal; provide ∼5 days employment; and provide 63% materials cost savings for electrode preparation in comparison to purchasing commercially available chloroplatinic acid hydrate. The proposed local industrial symbiosis would, per year, divert ∼50 g of platinum from landfill, avoid up to 1400 kg of CO2 emissions associated with primary production of an equivalent quantity of platinum, and give enough platinum to produce catalytic electrodes for ∼500 m2 of dye-sensitized solar cells, which could supply clean energy for 12 homes in the locality. The process exemplifies the environmental, economic and social benefits available through adoption of circular practices, which make use of secondary materials available within the local economy by valorizing wastes. The process also overcomes economic barriers to critical raw materials (CRMs) recovery from dissipative applications.

FORMATION OF TECHNOLOGICAL INDICES OF DRY POWDER OF CABBAGE

One of the resource-saving methods of drying, from the point of view of preserving food and biological value, providing the appropriate recovery properties of dried food products (DFP) and energy intensity of the process, is drying with mixed heat supply (MHS drying). The scientific concept of work on the formation of a universal and DFP stable functional and technological potential is formulated, which is the basis for modeling and designing the formulation composition and technology of food products by groups and types with its use or interchangeability. As the subject of research for the formation of quality indicators of cereals, white cabbage is selected, as it is a typical vegetable for Ukraine and accordingly has a high degree of assimilation of natural micronutrients in the human body. Structural studies have shown the predominantly crystalline structure of polysaccharides, that is, less than their transformation under conditions of MHS drying, as compared with convective conditions. The effect of MHS drying on the formation of DFP quality indicators is determined by the method of recording IR spectra with Fourier transform. For studies of the violation of total internal reflection, it has been established that the process of DFP reduction leads to an increase in the availability of organic substances in the solvent, which will facilitate the extraction of extractives in the recovery of raw materials. It is established by the number of aroma, the more aromatic-forming substances are contained in the MHS drying samples irrespective of the process temperature, less in the dried samples of the convective method. This is due to the reduction of thermal and thermal effects during MHS drying, which slows down chemical transformations and removes aromatic substances. It is proved by the tensometric method, with the convective method due to shrinkage during dehydration, the changes during sorption and desorption are insignificant. When MHS drying, such changes are expressed: during the sorption of vapors, DFP is well restored, the capillaries swell, so the differential distribution function of the pores expands, the average radius of the capillaries increases 4 ... 6 times. The research results make it possible to form the functional and technological parameters of cabbage powder, to simulate the formulation of new food products with this ingredient and to optimize the production technology.

Re-using bauxite residues: benefits beyond (critical raw) material recovery.

Since the world economy has been confronted with an increasing risk of supply shortages of critical raw materials (CRMs), there has been a major interest in identifying alternative secondary sources of CRMs. Bauxite residues from alumina production are available at a multi‐million tonnes scale worldwide. So far, attempts have been made to find alternative re‐use applications for bauxite residues, for instance in cement / pig iron production. However, bauxite residues also constitute an untapped secondary source of CRMs. Depending on their geological origin and processing protocol, bauxite residues can contain considerable amounts of valuable elements. The obvious primary consideration for CRM recovery from such residues is the economic value of the materials contained. However, there are further benefits from re‐use of bauxite residues in general, and from CRM recovery in particular. These go beyond monetary values (e.g. reduced investment / operational costs resulting from savings in disposal). For instance, benefits for the environment and health can be achieved by abatement of tailing storage as well as by reduction of emissions from conventional primary mining. Whereas certain tools (e.g. life‐cycle analysis) can be used to quantify the latter, other benefits (in particular sustained social and technological development) are harder to quantify. This review evaluates strategies of bauxite residue re‐use / recycling and identifies associated benefits beyond elemental recovery. Furthermore, methodologies to translate risks and benefits into quantifiable data are discussed. Ultimately, such quantitative data are a prerequisite for facilitating decision‐making regarding bauxite residue re‐use / recycling and a stepping stone towards developing a zero‐waste alumina production process. © 2018 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

WEEE collection and CRM recovery trials: piloting a holistic approach for Scotland

<p>Re-Tek UK and its partners, Enscape Consulting and the University of West of Scotland commenced trials for the collection and recovery of critical raw materials from waste electrical and electronic (WEEE) products in July 2016. Sponsored by the EU LIFE funded project ‘Critical Raw Material Closed Loop Recovery’ coordinated by WRAP with EARN, ERP UK Ltd, KTN Ltd and Wuppertal Institute as beneficiaries. The trials are aimed at boosting the recovery of critical raw materials (CRMs) from household waste electrical and electronic products (WEEE) and Information Communications Technology (ICT) in particular, after functioning equipment is separated out for re-use. The new collection models provided residents with the opportunity to drop-off unwanted electrical and electronic appliances at a time and place that suits them, through a collaborative approach which encourages local authorities, educational establishments, businesses, and Social Enterprises, etc to act as hub sites. Hubs were designed to minimize product damage and encourage drop-off, rather than hoarding. Extraction methods developed after the collection phase of the trial looked at the opportunity to recover cobalt, gold and silver from ICT products, with the potential to inform how a more sustainable supply chain could be developed in Scotland. The elements studied were selected to demonstrate financial opportunity (gold/silver) and a strategic priority material (cobalt) for long term supply. These are based on bioleaching and electrochemical recovery using novel carbon based electrode systems, and chemical processing methods using extraction techniques with an assessment of pilot performance and scale up challenges. Our report is on the state of progress towards practical solutions to WEEE and CRM recovery.</p>

Raw materials recovery from spent hydrochloric acid-based galvanizing wastewater

The composition of spent hydrochloric acid-based pickling liquors, deriving from the galvanizing industry, greatly depends on how long the bath has been used for pickling. We considered solutions containing 40–50 g L−1 of iron and zinc (as FeCl2 and ZnCl2) and 130–220 g L−1 of chloride, and used tri-butyl phosphate (TBP) and di-(2-ethylhexyl) phosphoric acid (D2EHPA) in kerosene as extraction solutions. From the spent liquors, zinc was selectively extracted and then recovered from the organic phase by using water or dilute hydrochloric acid. By using the kinetic results obtained for TBP and D2EHPA, recovery selectivity of zinc over iron (αZn/Fe) was estimated to be of 16.7 and 0.5, respectively. According to the McCabe & Thiele diagram for an organic to aqueous ratio of 2, three stages of extraction are sufficient to remove about 98% of the zinc from a real solution. The remaining solution of FeCl2 can be used to recover HCl and FeSO4 through the so-called “sulphuric acid distillation”. Finally, the recovered HCl can be used as a raw material, together with limestone, to produce CaCl2. Overall, an integrated process to recover the above-mentioned raw materials (Zn salts, FeSO4·7H2O and CaCl2) is presented: all products have been obtained in a ready-to-sell form, minimizing the waste according to the strategies of the “circular economy” and the “near-zero discharge” of hazardous chemicals.

Manufacturing of Ø 1,000 Grade Large Diameter Round Bloom and Development of Cost Effective Hot Forging Process Using the Round Bloom

Taewoong is an open die forging company, specialized in the production of hot forged and ring rolled parts. Recently, Taewoong utilized continuous casting facilities that can manufacture O 1,000 grade large diameter round bloom to increase competitiveness of the company. This study focuses installed continuous casting facilities and ring rolling process using manufactured O 1,000 grade round bloom. Constitution of installed facilities was introduced and characteristics of the facilities, EAF (Electric Arc Furnace), LF (Ladle Furnace), VD (Vacuum Degassing), VOD (Vacuum Oxygen Decarburization) and CC (Continuous Casting) were described. Also, ring rolling experiments were performed using manufactured O 1,000 grade round bloom. Hot forging process design was performed to fabricate sound products. Work sequence design was performed using FE analysis software and optimal forging work sequence was derived. With the results, sound forged parts were formed and improvement of competitiveness was verified. Raw material recovery ratio was increased and the number of process and processing time were decreased. The results show utilized continuous cast facilities give opportunity to be a world competitive company by increasing competitiveness of the company.

Evaluating the effects of environmental regulations on a closed-loop supply chain network: a variational inequality approach

Global climate change has encouraged international and regional adoption of pollution taxes and carbon emission reduction policies. Europe has taken the leadership in environmental regulations by introducing the European Union Emissions Trading System (EU-ETS) in 2005 and by promoting a set of policies destined to lower carbon emissions from energy, industrial, and transport sectors. These environmental policies have significantly affected the production choices of these European sectors. Considering this framework, the objective of this paper is to evaluate the effects of the application of environmental policies in a multitiered closed-loop supply chain network where raw material suppliers, manufacturers, consumers, and recovery centers operate. In particular, we assume that manufacturers are subject to the EU-ETS and a carbon tax is imposed on truck transport. In this way, the developed model captures carbon emission regulations, recycling, transportation and technological factors within a unified framework. In particular, it allows for evaluating the impacts of the considered environmental regulations on carbon emissions, product flows, and prices. The proposed model is optimized and solved by using the theory of variational inequalities. Our analysis shows that the combined application of the EU-ETS at the manufacturers’ tier and the carbon tax on truck transport implies additional costs for producers that reduce their good provisions. On the other side, this has a positive outcome for the environment since $$\hbox {CO}_2$$ emissions reduce. Moreover, an increase of the efficiency level of the recycling process increments the availability of reusable raw material in the reverse supply chain. Finally, the distance between a couple of CLSC tiers plays a very important role. The lower is the distance covered by vehicles, the higher is the production of goods and the lower is the amount of $$\hbox {CO}_2$$ emitted.

Challenges for critical raw material recovery from WEEE – The case study of gallium

Gallium and gallium compounds are more frequently used in future oriented technologies such as photovoltaics, light diodes and semiconductor technology. In the long term the supply risk is estimated to be critical. Germany is one of the major primary gallium producer, recycler of gallium from new scrap and GaAs wafer producer. Therefore, new concepts for a resource saving handling of gallium and appropriate recycling strategies have to be designed.This study focus on options for a possible recycling of gallium from waste electric and electronic equipment. To identify first starting points, a substance flow analysis was carried out for gallium applied in integrated circuits applied on printed circuit boards and for LEDs used for background lighting in Germany in 2012. Moreover, integrated circuits (radio amplifier chips) were investigated in detail to deduce first approaches for a recycling of such components. An analysis of recycling barriers was carried out in order to investigate general opportunities and risks for the recycling of gallium from chips and LEDs.Results show, that significant gallium losses arose in primary production and in waste management. 93±11%, equivalent to 43,000±4700kg of the total gallium potential was lost over the whole primary production process until applied in electronic goods. The largest share of 14,000±2300kggallium was lost in the production process of primary raw materials. The subsequent refining process was related to additional 6900±3700kg and the chip and wafer production to 21,700±3200kg lost gallium. Results for the waste management revealed only low collection rates for related end-of-life devices. Not collected devices held 300 ± 200 kg gallium. Due to the fact, that current waste management processes do not recover gallium, further 80 ± 10 kg gallium were lost.A thermal pre-treatment of the chips, followed by a manual separation allowed an isolation of gallium rich fractions, with gallium mass fractions up to 35%. Here, gallium loads per chip were between 0.9 and 1.3mg. Copper, gold and arsenic were determined as well. Further treatment options for this gallium rich fraction were assessed. The conventional pyrometallurgical copper route might be feasible. A recovery of gold and gallium in combination with copper is possible due to a compatibility with this base-metal. But, a selective separation prior to this process is necessary. Diluted with other materials, the gallium content would be too low.The recycling of gallium from chips applied on printed circuit boards and LEDs used for background lighting is technically complex. Recycling barriers exist over the whole recycling chain. A forthcoming commercial implementation is not expected in nearer future. This applies in particular for chips carrying gallium.

Solidification of hazardous waste as a part of the raw material recovery process

Paper presents the process capabilities for solidification hazardous waste. In the first part of the article the authors present general technologies and methods in a comparative model. The following section describes the results of market research for the most advanced and innovative solidification technologies. Comparative analysis of the material has shown and described the three most promising, leading-edge technologies of waste solidification avalible on the Polish market.

Solidification of hazardous waste as a part of the raw material recovery process

Paper presents the process capabilities for solidification hazardous waste. In the first part of the article the authors present general technologies and methods in a comparative model. The following section describes the results of market research for the most advanced and innovative solidification technologies. Comparative analysis of the material has shown and described the three most promising, leading-edge technologies of waste solidification avalible on the Polish market.

A Closed-Loop Supply Chain Equilibrium Model with Random and Price-Sensitive Demand and Return

This paper proposes a decentralized closed-loop supply chain network model consisting of raw material suppliers, manufacturers, retailers, and recovery centers. We assume that the demands for the product and the corresponding returns are random and price-sensitive. Retailers and recovery centers face penalties associated with shortage demand and supply, respectively. We derive the optimality conditions of the various decision-makers, and establish that the governing equilibrium conditions can be formulated as a finite-dimensional variational inequality problem. The qualitative properties of the solution to the variational inequality are discussed. Numerical examples are provided to illustrate the effects of demand and return uncertainties on quantity shipments and prices.