Looking Back - Lessons from Our E-Waste Recycling Journey

1. Introduction

The discussions in earlier blog posts have delved into the value of metals in various types of electronic waste (E-Waste), the magnitude of E-Waste generation, and different processing methods. A search on these subjects reveals extensive articles and technical papers. Nevertheless, certain crucial aspects related to the operational and financial dimensions of managing an e-waste business are seldom explored and are frequently less comprehended by individuals not directly engaged in the operations of such enterprises. Operators typically refrain from openly discussing these matters due to their proprietary nature, contributing to their competitive advantage.

2. Type of Processor

E-waste is classified into 4 categories with Printed Circuit Boards (PCBs) containing the highest metal values (see table below). An E-Waste processor faces the crucial task of identifying the optimal niche for their business, which can range from a narrow focus on a specific category or a more encompassing enterprise with vertical and horizontal integration that includes various feed types and extensive processing infrastructure.

Geographic location can be a key factor for the enterprise, considering factors such as the local availability of e-waste and proximity to transportation hubs which potentially reduce shipping costs. Operating in regions with lower labor costs may facilitate more extensive manual sorting and disassembly.

Since PCBs contain the highest metal values, they are often seen as being the most attractive opportunity for e-waste recyclers.

3. Printed Circuit Boards Recycling

Initiating a recycling venture focused on printed circuit boards (PCBs) is often an appealing choice for start-ups or smaller enterprises, primarily driven by the high value associated with this type of e-waste. The value of PCBs lies in their metal content, with copper, gold, silver, and palladium being the most valuable metals that smelters are willing to compensate for.

Notes: Based on prices of metals of February 2024. The total prices and calculations are estimates. The prices and values are in US dollars. The assumption is made that PCB wt. for different categories of e-waste is the same as in 2021.

The primary step in establishing a PCB recycling business involves comprehending and establishing network connections to secure these materials. Contrary to common belief, the acquisition costs for these materials can be substantial, influenced not only by their market price but also by transportation expenses. The strategic location of the business becomes crucial in this context. Additionally, a critical aspect is to grasp the various categories of PCBs, their respective metal values, and potential problematic impurities to avoid overpaying for the feedstock.

Type of PCB Recyclers

Once a decision has been made to enter the PCB recycling market, the processor will have to decide what level of processing they will engage in with each level requiring higher levels of capital and operating costs.

3.1 Disassemble and/or Refurbish

A processor may choose to buy PCBs (i.e. computers) or other electronic equipment still in their housings and engage primarily in disassembly to recover the valuable components followed by the sale of the boards. This type of operator could also include refurbishing devices for reuse or resale where possible. In some cases, there may be a case for including data destruction services in a business of this type.

3.2 Sort & Consolidate

Some operators have chosen to become sorters and consolidators of PCBs with an eventual objective of reselling them to other processors or to a smelter. Some of these recyclers obtain their material through existing channels because they are already in the business of recycling other metals. Sorting allows for grouping similar types of PCBs into batches based on their value. Gold content is frequently used as a basis for characterizing the batches or lots. Others may choose to just mix all PCBs because the cost of sorting, primarily due to local labor costs, can be excessive relative to the value of the boards. These “middlemen” types of operations, acting as intermediaries, can be great sources of bulk supply for more integrated operators. The big challenge for all parties is understanding the true value of these lots. The value of the lot can be only estimated with some degree of confidence after shredding, mixing, and assaying a properly recovered sub-sample from the lot. Given the non-homogenous nature of e-waste, this is a very difficult and important step.

3.3 Physical Separation – Shredding - Concentration

In general, larger PCB processors tend to favor an integrated facility encompassing disassembly, sorting, as well as physical and mechanical separation, including concentration. To secure feedstock for their operations, they must acquire it from various sources on the open market, including sorters and consolidators mentioned earlier.

The diverse stages of shredding and grinding facilitate the recovery of metals such as steel and aluminum, while simultaneously removing plastics and board materials, which consist of epoxy laminates and fiberglass board. This methodology results in two distinct products: a heavy, high-grade concentrate containing most of the copper, gold, silver, and palladium, and a light fraction (non-metallic fraction) primarily composed of fiberboard material and plastics. Achieving perfect separation is nearly impossible, leading to some metals being present in the light fraction. The creation of a concentrate offers several advantages:

• Reduction in mass for shipping, as there's no need to transport steel, aluminum, and plastics present in the PCBs.
• Enhanced returns from smelters due to the higher-grade nature of the product.
• Less heterogeneity in the material, enabling improved sampling and, consequently, more accurate estimates of the contained metals through chemical analysis (assaying).

4. Issues to Watch Out For

Individuals seeking to establish a new PCB recycling venture should be mindful of several issues often overlooked in articles and papers. These concerns revolve around comprehending the value of PCBs, and they encompass purchasing feedstock based on its indicated value, assessing the actual value, particularly when selling to a smelter after processing, and addressing hazardous or penalty elements or compounds present in the product intended for sale to smelters. The following points delve into these considerations:

• Feedstock Valuation: When procuring feedstock, it's crucial to understand its indicated value and make informed decisions based on this assessment.
• Actual Value Determination: Determining the actual value of processed PCBs becomes paramount, especially when the intention is to sell the material to a smelter. This requires a nuanced understanding of the recovered metals' quality and quantity.
• Hazardous or Penalty Elements: Identification and management of hazardous elements or compounds within the processed product are essential. This not only ensures compliance with health and safety regulations but also influences the marketability of the recycled material.

These considerations are pivotal for the success and sustainability of a PCB recycling enterprise, addressing challenges that may not be readily apparent in the standard literature on the subject.

4.1 Purchasing PCBs

There are databases developed by the industry and or individual PCB processors that list the metal content, and hence their value, of various types of PCBs however it is not easy to assess whether any purchased lot contains only certain types of boards by visual inspection. One cannot determine the true value of the lot until it has been processed, shipped to a smelter and the smelter has provided the settlement document. The purchased lots can also contain material that is not consistent with the types of boards indicated by the seller. Hence, mispricing of boards is not uncommon.

We spoke to an executive at a company formerly involved in purchasing PCBs who stated “We often found that the purchased batches did not measure up to the stated value or contained the promised material. Regardless of origin, loads were often contaminated with batteries or other hazardous materials, contained large pieces of steel or other low-value metals to inflate the weight, and many had valuable chips and other components removed from the PCB material by the vendor.”

Several websites provide market prices for various types of boards (see Table 1) and one can use them to value a lot. However, most lots contain a variety of board types so there is always a challenge of having to sort through the whole batch to assess its true value.

Table 1. Example of payout rates for various types of PCBs as of January 2024 | Source: https://boardsort.com

4.2 Understanding the Metal Content

The most effective method to determine the metal content of PCBs involves conducting assays internally or by utilizing an external laboratory. For a dependable chemical assay, it is essential to collect and prepare the sample correctly. The best place to collect a sample is at the tail end of the process, where the PCBs have undergone shredding, grinding to fine particle size, and concentrated in preparation for shipment. Implementing a proper sample collection and splitting system is crucial. However, it is worth noting that the cost of analysis can be substantial as only a limited number of labs possess the expertise to carry out the analysis accurately. Additionally, turnaround times at external labs can extend to several weeks.

The main challenge with assaying at the end of the process is that it is well after the e-waste lots have been purchased and paid for.

There are companies using image analysis and artificial intelligence to assess the value of different types of boards before purchase. This involves correlating the metal content with images of the boards. Consideration should be given to this approach and other pre-emptive methods to avoid overpaying for feedstock.

4.3 Hazardous Penalty Items

PCBs are known to contain various hazardous materials that need to be monitored not only during processing but also for the sale of the final processed material to smelters. Smelters have limits on certain nuisance and toxic elements and materials that they accept as feed for their refining process. These include but are not limited to:

• brominated flame retardant (BFR) group
• beryllium
• other halogenated organic compounds
• arsenic, barium, cadmium, lead, mercury

Once again, understanding the impact of these elements and compounds before purchasing the material can be valuable in maximizing the return from processing and selling the products to a smelter.

5. Downstream E-Waste Processing Routes

Smelters, which primarily use pyrometallurgical processes, are the most common downstream destination for physically/mechanically processed e-waste. While smelters primarily use furnaces at the front end of the operation, some incorporate downstream hydrometallurgical processing to refine the products generated from pyrometallurgical smelting.

^{Flow sheet of Umicore's Hoboken integrated smelter and refinery plant. Source: https://www.researchgate.net/publication/284043293_Recycling_of_Electronic_Scrap_at_Umicore_Precious_Metals_Refining}

There are some well-understood disadvantages to outsourcing the final processing of the e-waste stream due to lower realized value, shipping costs, lengthy payment terms, and locked-up working capital. As a result, an opportunity exists for some recyclers to consider on-site processing. Since smelting is difficult at a small scale due to economies of scale, capital costs, and environmental issues due to off-gases, hydrometallurgical processing may be a better option.

5.1 Direct hydrometallurgical processing

Unlike smelting, hydrometallurgical processes can start small and can be scaled up to meet demand with a much smaller starting capital required. Furthermore, liquid streams, unlike fugitive gaseous emissions, are generally more easily contained, recycled, and/or treated before discharge.

Copper has been identified as the best species to target in PCBs via hydrometallurgy as it can be readily digested by various acids and recovered by direct electrowinning.

Several process issues should be addressed for the digestion of the ground PCB material:

• Minimizing the top particle size of the ground material. Finer grinding produces improved leaching kinetics and maximizes recovery.
• Minimizing the presence of iron in the leaching process. Iron can interfere with leaching and more importantly reduce electrowinning efficiency.
• Minimizing aluminum content which can consume significant amounts of acid.
• Dealing with the tin not only consumes some of the lixiviant but can create additional process issues. Note that feeds with high tin content may allow for economic recovery of the tin as a by-product.
• How to deal with the final residue after leaching which contains almost of the precious metals (Au, Ag and Pd). It can be either processed on-site or sold to a precious metals’ refiner.

After the copper metal is dissolved in the solution following digestion, applying a direct current allows copper to be deposited onto the cathode through electrolysis.

Extensive hydrometallurgical testing has been conducted on the ground and concentrated PCBs, resulting in the successful production of electrowon copper using an emew electrowinning system at the back end of the process.

The emew electrowinning system operates using cylindrical cells that facilitate rapid circulation of the electrolyte over the cathode, enhancing mass transfer and enabling the production of high-quality copper cathodes even at lower concentration levels. As copper is electrolyzed, the system regenerates acid within the cell, which can be reused in the copper removal process, thereby minimizing overall acid consumption and waste generation.

Furthermore, emew electrowinning cells are designed as closed systems, effectively addressing safety concerns such as acid mist and noxious gases, thus creating a safer work environment. Additionally, the emew system features auto-stripping of copper cathodes from starter sheets, eliminating the need for extra stripping equipment required in conventional electrowinning cells.

Have a question about your application? We will be happy to chat! 

Additional resources 

In this video, Dr. Michael Korzenski provides valuable insights into the extraction of precious metals from electronic waste. He also addressed our queries regarding the value of these metals in e-waste and the techniques employed to recover them.