How to Recycle Waterjet Abrasive Safely

Recycling waterjet abrasive can save you money, reduce waste, and help comply with regulations. Abrasive costs often make up 50% of waterjet operating expenses, but recycling can cut these costs significantly. Systems can recover 50-90% of used abrasive, and some businesses have saved over $12,000 in just four months by recycling instead of buying new material. Beyond cost savings, recycling reduces disposal challenges and helps avoid environmental risks.

Key Points:

• Cost Savings: Garnet recycling reduces abrasive expenses by up to 85% in high-volume operations.
• Efficiency: Recycled abrasive retains cutting performance and can be blended with new material for consistent results.
• Regulatory Compliance: Recycling helps meet disposal rules and avoid hazardous waste issues.
• Environmental Benefits: Proper handling prevents contamination and supports responsible waste management.

Recycling systems like Hypertherm's EcoSift™ or Flow Waterjet's removal systems make it easier for businesses to recover and reuse abrasive. Smaller shops can also benefit by storing used abrasive for future recycling. Whether you manage recycling on-site or use third-party services, the long-term savings and reduced disposal costs make this a smart choice for any machine shop.

80 Mesh vs. Recycled Abrasive Waterjet Cut Comparison

Understanding Waterjet Abrasive Waste

Knowing what goes into waterjet abrasive waste and the rules surrounding its disposal is key to managing it effectively. By understanding the components and regulations, businesses can make informed decisions about recycling, disposal, and safety.

Types of Abrasives Commonly Used

Garnet is the go-to abrasive for most waterjet applications in the U.S. This naturally occurring mineral is favored for its cutting efficiency and relatively safe handling. Its popularity stems from its ability to deliver precise cuts while being cost-effective.

What sets garnet apart is its durability. During the cutting process, garnet doesn’t break down chemically, meaning the core particles remain intact and can often be reused. With proper recycling equipment, some users report recovering up to 90% of their garnet. However, as garnet is reused, its particles become smaller and less angular, which reduces its cutting effectiveness over time.

What’s in Spent Abrasive

Spent abrasive is more than just used garnet - it’s a mix of three main components: the original abrasive, fragments of the material being cut, and water. When cutting materials like steel, aluminum, or composites, tiny particles from the workpiece embed themselves in the abrasive.

Alan Bennett, market manager at Barton Mines Co., explains:

If you are cutting lead or beryllium copper, then you may have a hazardous waste situation. For most other materials, the amount of the scrap material in the abrasive is so small that it is rarely a problem. Even most stainless steels are usually not an issue unless they contain a high nickel or chrome content.

The presence of hazardous materials is a major concern. Cutting materials like lead, beryllium, or certain types of stainless steel can contaminate the entire batch of spent abrasive, requiring special handling and disposal. Additionally, the water used in the cutting process can absorb contaminants from both the abrasive and the workpiece. If this water contains metals or other pollutants, it adds another layer of complexity to waste management.

Interestingly, spent garnet can also find a second life in construction. It meets ASTM C618 standards as a pozzolanic material, thanks to its high levels of silica, alumina, and iron oxide - making it suitable for use in construction applications.

US Regulations and Requirements

Managing waterjet abrasive waste in the U.S. involves navigating a mix of local and federal regulations. As John Frosheiser, president of Custom Service and Design, notes:

All these [disposal] regulations are determined by local authorities, not even at the county level.

At the federal level, the Resource Conservation and Recovery Act (RCRA) outlines the rules. Subtitle C governs hazardous waste, while Subtitle D focuses on non-hazardous industrial waste and landfill standards. The Environmental Protection Agency (EPA) oversees hazardous waste management from creation to disposal, often referred to as "cradle-to-grave" control. Additionally, states often have their own RCRA programs, adding another layer of complexity.

One critical tool for determining regulatory obligations is the Toxicity Characteristic Leaching Procedure (TCLP). This test evaluates whether spent abrasive qualifies as hazardous waste based on the materials being cut. If the results show contamination above EPA limits, the waste requires special handling and disposal.

In some areas, used abrasive is classified as a "byproduct" rather than "waste", which can impact hauling rates and disposal costs. Improper storage of spent abrasive can also pose environmental risks. For instance, during floods, poorly stored materials can wash into local waterways, causing contamination.

To manage waste responsibly, machine shops should test their water and consult local water utilities about heavy metal limits. Reaching out to local environmental authorities is also crucial, especially when disposing of abrasive that may contain hazardous substances. This regulatory framework is an essential starting point for selecting effective recycling and disposal methods.

Methods for Recycling Waterjet Abrasive

Recycling waterjet abrasive not only reduces waste but also improves operational efficiency and cost-effectiveness. Machine shops have several ways to recycle spent abrasive, ranging from specialized on-site equipment to detailed processes that recover reusable material.

On-Site Recycling Equipment

One common approach involves screening and separation systems, which remove usable abrasive from waste material. These systems rely on particle size differences to separate intact garnet particles from fractured pieces and debris. The recovered abrasive is then dried and stored for reuse.

A well-known option is Hypertherm's EcoSift™ system, which was developed after Hypertherm acquired AccuStream. This unit is designed for consistent, high-volume operations and works best under specific conditions: cutting at 60 ksi or below, using 80 mesh garnet, and avoiding materials like plastic or wood that could clog the system. EcoSift requires a 60A breaker, 5 SCFM air, and 4 GPM water, producing up to 120 pounds of recycled abrasive per hour. For shops using around 20 tons of abrasive monthly, the system can pay for itself within two years when factoring in capital costs and operating expenses.

Another option comes from Flow Waterjet, which offers a portable abrasive removal system. This equipment uses vacuum technology to collect used abrasive into bulk bags, simplifying transport for disposal or off-site recycling. For larger-scale operations, industrial vacuum trucks can handle up to 700 tons of abrasive slurry per month, streamlining the collection process.

Step-by-Step Recycling Process

Recycling abrasive involves several key steps, starting with the collection of spent material - a mixture of garnet, debris, and water. This mixture is removed from the cutting tank and allowed to settle.

1. Washing and screening: The abrasive is washed and screened to remove fine debris and fractured particles that are no longer effective for cutting. This process ensures that only usable material moves forward. As Rich Ward, President of WARDJet, highlights:

   It is important that the amount of abrasive being washed and cleaned is balanced with the drying capacity of the recycling system.

2. Drying: After washing, the material undergoes a drying phase, which can take several days depending on the method. For example, at Garnet Recyclers of Washington, the mixture is deposited into an indoor pond for settling before the water is pumped out, initiating a multi-day drying process.
3. Secondary classification: Once dried, the abrasive is further classified to separate fine and coarse grains. This step ensures that only properly sized particles are included in the recycled mix.
4. Quality control testing: The final step involves testing the recycled abrasive to ensure it meets cutting standards and is free of contaminants. This is especially important when working with materials that might introduce unwanted residues.

Mixing Recycled and New Abrasive

Recycled abrasive is often blended with new material to maintain cutting performance while keeping costs in check. A common mix is 50% recycled and 50% new garnet, which provides consistent results.

Research suggests that mixing ratios can vary based on the application. For instance, studies on granite cutting found that a 40%-60% recycled garnet blend works well, with recycled garnet achieving about 70% of the efficiency of fresh garnet.

The shape of the abrasive particles also plays a role. According to Bradley Schwartz, Regional Product Manager at Jet Edge:

In Jet Edge's machines, 50% to 70% of the abrasive is not being used, it's actually the core of the jet.

This means many garnet particles remain intact after their initial use, making them ideal for recycling. However, regular monitoring and calibration are necessary when using mixed abrasives, as recycled particles often have altered shapes and sizes.

Interestingly, the type of garnet can affect performance. For example, recycled alluvial abrasive, which starts as rounded particles, may cut faster than new alluvial abrasive due to surface changes during its first use.

While recycling offers numerous advantages, machine shops should evaluate their specific needs. As R. Randolph Rapple, President of Barton International, points out:

Virgin garnet is widely available and relatively low-cost. There is no shortage of garnet abrasives in the world. No one running a waterjet should be worried about their next order of abrasives.

Safe Handling and Storage of Recycled Abrasive

Following proper handling and storage practices for recycled abrasive not only ensures worker safety but also helps maintain material quality and complies with environmental standards. Recycled waterjet abrasives require the same care and precautions as new materials to protect both workers and the integrity of the material.

Required Safety Equipment

Working with recycled abrasive can present health risks, especially due to fine particles that may become airborne. To mitigate these risks, wearing personal protective equipment (PPE) is a must. Here’s what’s essential:

• Goggles or masks: Prevent splashing and protect against fine particles.
• Soundproof earmuffs: Minimize damage from high noise levels.
• Cut-resistant gloves: Offer protection when handling abrasive materials.
• Non-slip safety shoes: Reduce the risk of slips and falls.
• Long-sleeved protective clothing: Recommended for additional coverage.

Respiratory protection is particularly critical when dealing with recycled abrasive, as it may contain contaminants from previous uses. To minimize exposure to airborne particles, use vacuums equipped with HEPA filters or apply wet methods for cleaning dust. Proper ventilation in work areas is also essential for maintaining air quality and reducing risks.

Eye and face protection should go beyond standard safety glasses. Use safety goggles that seal around the eyes to prevent fine particles from causing irritation or injury.

Once the appropriate PPE is in place, focus on storage and labeling to maintain the material’s quality and usability.

Storage and Labeling Guidelines

Proper storage of recycled abrasive is key to preserving its quality and preventing contamination, which can affect cutting performance. Here’s how to store it correctly:

• Keep abrasives off the ground in a climate-controlled space, maintaining temperatures between 64°F and 79°F and humidity at 45% RH. Avoid exposure to moisture, which can lead to clumping and degradation.
• Protect the material from extreme temperatures and direct sunlight, as these conditions can compromise its usability.
• Store abrasives in racks or on flat surfaces, keeping them shielded from heavy traffic and vibrations. Depending on the container type, the material can be stored horizontally or suspended vertically, following manufacturer recommendations.

Safety signage is also necessary in storage and processing areas. Use warning signs to mark areas with blasting dust and alert workers to required PPE.

Quality Control Inspections

Maintaining the performance of recycled abrasive requires regular quality control checks. These inspections ensure the material meets performance standards and remains safe for use. Recycled materials demand more frequent testing compared to new abrasives.

• Particle size distribution: Regularly monitor this to ensure proper separation during recycling. Use USA mesh screens to verify that coarse contaminants (20 mesh or larger) and fines (80-90 mesh or smaller) are being removed effectively.
• Separation system monitoring: Conduct visual checks multiple times per shift. Inspect discharge tubes from the air-wash separator and rotary drum to ensure usable abrasive isn’t being lost.
• Performance testing: Verify the effectiveness of recycled abrasive through testing and microscopic analysis. Studies show up to 60% of used abrasive can meet the specifications of new material. Expect a breakdown rate of 20-25% at 90-110 psi at the nozzle when using quality recycled abrasive.
• Sampling procedures: Collect samples directly from the air wash as the abrasive falls past the swinging baffle or from the air-wash discharge tube. Avoid sampling from stationary sources. Use #80 or #100 mesh screens to check for excessive fines, and #60 mesh screens to ensure usable garnet isn’t being over-extracted.

Additionally, clean the trough beneath the rotary drum before each shift, and inspect the air wash for a uniform and full abrasive curtain to maintain proper separation. These steps help ensure the recycled abrasive performs effectively while maintaining safety standards.

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Disposal and Reuse Options

When recycling is no longer an option, machine shops have several ways to manage used abrasive that can help minimize environmental impact and, in some cases, reduce costs.

Third-Party Reprocessing Services

Specialized companies offer reprocessing services to give spent waterjet abrasive a second life in other industries. Take Garnet Recyclers of Washington, for instance. They handle around 600 to 700 tons of abrasive monthly from waterjet tanks in northwest Washington. Through multiple processing stages, they recycle garnet, which is then used in concrete and asphalt applications as a filler.

These companies also manage the logistics - like collection, testing, and reprocessing - and conduct TCLP testing to ensure compliance with environmental standards. Some manufacturers, such as those producing pavers, may even pay for used abrasive, provided it’s supplied in consistent, large quantities. Additionally, recycled garnet can be repurposed as a sandblasting medium or as an additive to strengthen concrete and block mixtures.

Supplier Take-Back Programs

Many abrasive suppliers now offer take-back programs to collect and reprocess used materials. GMA Garnet, for example, runs a return program that transforms spent garnet into high-quality abrasive for resale. This program includes TCLP analysis, transportation, and handling, with costs depending on factors like distance and lab fees.

Shops producing a steady stream of spent abrasive often find this option appealing. Florian Baumann, General Manager at CUTCUT, highlights the benefits, stating:

We have finally found GMA, a partner who meets our requirements in managing our used garnet responsibly and at a reasonable cost.

Suppliers take care of testing and transportation, and since garnet abrasive is generally inert and nonhazardous (unless contaminated by materials being cut), these programs can be a practical solution. To explore this option, reach out to your waterjet OEM or a GMA representative for details on removing spent garnet from your tank.

When recycling or take-back options aren’t workable, proper disposal becomes the next step.

Landfill and Hazardous Waste Disposal

If neither recycling nor reuse is feasible, machine shops must dispose of spent abrasive responsibly. However, disposal regulations vary by region, which can make the process tricky. Local authorities, not standardized rules, dictate the requirements.

Before disposal, TCLP testing is necessary to determine if the abrasive is classified as hazardous. Alan Bennett, Market Manager for Barton Mines Co., explains:

If you are cutting lead or beryllium copper, then you may have a hazardous waste situation. For most other materials, the amount of the scrap material in the abrasive is so small that it is rarely a problem. Even most stainless steels are usually not an issue unless they contain a high nickel or chrome content.

Reducing the weight of used abrasive by draining water can help lower disposal costs. Bennett also points out:

Because of the density of abrasive, reducing transportation distance is vital to reducing this cost.

In some cases, municipalities classify used abrasive as a "byproduct" rather than waste, which can result in lower hauling fees. Alternatives like waste-to-energy processes or fuel blending are also worth considering, as traditional landfills contribute significantly to methane emissions - about 15% of the U.S. total. Methane, over a century, has 28 times the global warming potential of carbon dioxide.

For shops generating large or small quantities of hazardous waste, notifying the EPA or state agencies and using proper manifests during transport is required. Staying up to date with local waste and water disposal regulations is essential, and consulting with local environmental authorities can provide clarity before disposing of spent abrasive.

Comparing Recycling and Disposal Methods

Cost, Efficiency, and Impact Comparison

When managing spent waterjet abrasive, machine shops often face a crucial decision: recycle or dispose. This choice can heavily influence both their operational expenses and their environmental impact. By weighing the trade-offs, shops can tailor their approach to fit their specific needs and priorities.

Financial considerations are often at the forefront of this decision. Recycling can significantly reduce operating costs - by as much as 85% - since abrasives account for roughly half of waterjet expenses. For high-volume operations, the savings can be particularly striking. For instance, one company recovers about 30 pounds of reusable abrasive per hour, while another estimates it won’t need to purchase new abrasive for 18 months thanks to recycling.

Gale Orem, owner of EMS, sums it up succinctly:

"It's the closest I have come to printing money".

However, recycling isn’t without its challenges. It requires an upfront investment in equipment, regular maintenance, and dedicated operator time. On the other hand, disposal involves fewer initial costs but comes with ongoing expenses for collection, transportation, and landfill fees, which can vary widely depending on location. Ultimately, recycling trades higher upfront costs for long-term savings, while disposal offers simplicity at the expense of recurring fees.

Efficiency and regulatory factors also play a role in the decision. Recycling involves processing, quality checks, and occasional maintenance downtime. Disposal, while simpler, is subject to highly variable local regulations. Recycled abrasive can even outperform virgin material, cutting faster and cleaner in some cases.

As John Frosheiser, president of Custom Service and Design, highlights:

"The difficult thing for anyone is that all these [disposal] regulations are determined by local authorities, not even at the county level".

This variability in regulations can make disposal unpredictable, especially for businesses operating in multiple locations. Recycling, by contrast, offers a more consistent and manageable alternative.

Environmental impact is becoming an increasingly important factor. Recycling reduces landfill waste and conserves resources, making it the more sustainable option. However, some studies have noted that many in the abrasive waterjet (AWJ) industry still lean toward disposal because recycling can be seen as more expensive than purchasing new material.

R. Randolph Rapple, president of Barton International, offers a practical perspective:

"Virgin garnet is widely available and relatively low-cost. There is no shortage of garnet abrasives in the world. No one running a waterjet should be worried about their next order of abrasives".

Volume considerations often tip the scales. High-volume operations gain the most from recycling due to economies of scale, while smaller shops might find disposal more practical when factoring in equipment costs and labor requirements.

Ultimately, the decision comes down to evaluating the total cost of ownership. By considering operational volume, financial structure, and environmental objectives, shops can choose the method that best aligns with their goals. Balancing upfront investments with long-term benefits is key to making the right choice.

Conclusion

Recycling waterjet abrasive isn’t just about being environmentally conscious - it’s a practical move that can have a big impact on your bottom line. With abrasive costs making up nearly 75% of waterjet operating expenses, starting a recycling program is one of the simplest ways to cut costs significantly.

Research shows that up to 60% of used abrasive can meet new standards, and as much as 81% can be reused after the first cut, directly lowering material expenses. These savings go hand in hand with the broader benefits of adopting sustainable practices.

Beyond the financial advantages, recycling abrasive also strengthens your commitment to greener operations. As GMA Garnet emphasizes:

Environmental sustainability has become a concept in many parts of the world and a topic that will certainly develop in the future, and as a supplier we also have a responsibility and an obligation to contribute.

Waterjet cutting is already one of the cleanest manufacturing methods, producing no harmful byproducts or emissions. Adding abrasive recycling to your process makes it even more eco-friendly.

To succeed with recycling, it’s essential to follow proper procedures. Monitor abrasive performance closely, maintain strict quality control, and remove particles smaller than 90 μm for disposal. For larger operations, automated recycling systems can streamline the process and boost efficiency.

For machine shops aiming to stay competitive, abrasive recycling offers a triple advantage: reduced costs, strengthened environmental responsibility, and improved operational efficiency. While there’s an upfront investment in recycling equipment and processes, the long-term savings and sustainability benefits make it well worth it.

Recycling isn’t just a smart choice - it’s becoming a necessity in today’s manufacturing landscape. Whether you run a high-volume facility or a smaller custom shop, exploring abrasive recycling could help you save money and contribute to a greener future. The real question is: can you afford not to?

For more tips and resources on sustainable machining practices, check out the Machine Shop Directory at https://machineshop.directory.

FAQs

What environmental and regulatory challenges can arise when recycling waterjet abrasive, and how can businesses address them?

Recycling waterjet abrasive comes with its own set of environmental concerns, particularly when dealing with waste that might contain contaminants like heavy metals or other hazardous substances. While most used abrasives don’t qualify as hazardous waste, they still require careful handling to avoid environmental harm. Businesses must also navigate various local, state, and federal waste management laws, which often include strict rules for disposal and recycling.

One effective way to tackle these challenges is by using closed-loop recycling systems. These systems reduce waste discharge by allowing abrasives to be reprocessed and reused. Regular cleaning and inspection of used abrasives can further ensure their safe reuse, all while keeping the environmental footprint in check. Additionally, staying updated on relevant regulations and partnering with certified waste management providers can make compliance easier while supporting environmentally responsible practices.

Does recycled waterjet abrasive perform as well as new abrasive, and what factors affect its quality?

Recycled waterjet abrasive can deliver performance comparable to new abrasive when it’s carefully processed and chosen. Key factors influencing its effectiveness include particle size, sharpness, and the degree of contamination from debris or wear. However, repeated use can cause particles to break down, which might slightly lower cutting efficiency.

To maintain top performance, it’s crucial to clean and sort the abrasive during recycling. Selecting the appropriate abrasive for your specific needs and adhering to proper recycling practices can help maintain cutting precision and efficiency while also minimizing waste.

What should machine shops consider when choosing between recycling waterjet abrasive on-site or using a third-party service?

When choosing between on-site recycling and third-party reprocessing for waterjet abrasive, machine shops need to weigh their budget, operational needs, and material requirements.

On-site recycling offers the potential for major savings - up to 85% - by reusing abrasive materials. This approach is not only cost-efficient but also reduces waste, making it a greener alternative. However, it does require an initial investment in recycling equipment and regular upkeep to maintain the abrasive's effectiveness.

In contrast, third-party reprocessing services deliver cleaner, more consistent abrasive material, which can enhance cut quality. This option removes the need for in-house recycling equipment but comes with added costs and logistical challenges, such as shipping the used material to the reprocessing facility.

The right choice depends on factors like production volume, available resources, and long-term financial goals. Each shop must balance these considerations to determine the most practical and economical solution.