Novel Approaches for Sulfate Removal from Water Discharges

OVERVIEW

U.S. Steel, the Seeker for this Wazoku Crowd Challenge, is seeking novel, effective, and scalable solutions for sulfate removal from water discharges at its Keetac plant in Minnesota.

Reducing sulfate concentration at Keetac’s water discharge outfalls is required in order to comply with strict permit conditions. U.S. Steel is open to any method or approach, considering the solution requirements, including but not limited to: biological, chemical, mechanical, process innovations, and more.

The ideal solution would reduce the sulfate concentration in the discharges, resulting in compliance while also minimizing capital/operating costs and secondary environmental impacts.

By taking part in and submitting to this Prize Challenge you are granting U.S. Steel a right to use (but not own) your submitted information, provided that U.S. Steel must determine award winners within 45 days from the start of evaluation, otherwise U.S. Steel retains the right to use only Awarded solutions.
 

This Challenge requires a written proposal to be submitted and the total guaranteed award pool of $25,000 will be paid, with at least one award of $10,000 or more and no award being less than $2,500. There is no assignment of IP Rights with this challenge.

Solvers may:

• Submit ideas of their own
• Submit third-party information that they have the right to use and further, the authority to convey to U.S. Steel this right with the right to use and develop derivative works
• Submit information considered in the public domain without any limitations on use

Submissions to this Challenge must be received by 11:59 PM (US Eastern Time) on May 13th, 2025.

Please review the later Participation Guidance section before submitting a proposal.

- Login or register your interest to start solving! -

Watch our webinar recording about this Challenge now to learn the evaluator's thoughts and how to craft the best solution:

ABOUT THE SEEKER & ELIGIBILITY

Founded in 1901, United States Steel Corporation is a leading steel producer. With an unwavering focus on safety, the Company’s customer-centric Best for All^® strategy is advancing a more secure, sustainable future for U. S. Steel and its stakeholders. With a renewed emphasis on innovation, U. S. Steel serves the automotive, construction, appliance, energy, containers, and packaging industries with high value-added steel products such as U. S. Steel’s proprietary XG3^® advanced high-strength steel. The Company also maintains competitively advantaged iron ore production and has an annual raw steelmaking capability of 25.4 million net tons. U. S. Steel is headquartered in Pittsburgh, Pennsylvania, with world-class operations across the United States and in Central Europe. For more information, please visit www.ussteel.com.

THE CHALLENGE

Background

The ”Iron Range” is a particularly iron-rich area around Lake Superior, in  northeastern Minnesota. U.S. Steel facility, Minnesota Ore Operations-Keetac, is located in Keewatin, Minnesota.

This facility is able to produce either direct-reduced (DR) iron ore pellets or blast furnace iron ore pellets, dependent on demand, which are both key components of the process to make steel.

As part of the production of these pellets and the ongoing processes of the plant, sulfates are produced that are then present in the water discharged by the facility. Sulfur can originate from the ore itself, and sulfate is naturally occurring in the groundwater and surface water surrounding the facility. The Keetac facility has 4 water discharge outfalls, dispersed around the site.

Each outfall contains different concentrations of sulfate, ranging from 20 to 200 milligrams per liter (mg/L) . In addition to the sulfate concentration ranges, each outfall flow volume can vary greatly depending on plant/mine activity and precipitation.

Figure 1: Example sulfate concentrations and flow volumes

Figure 2: Map of Water Flows

SD001, marked on the above Water Flow Diagram, is an internal outfall and therefore out of the scope of this Challenge. Please focus on solving for SD002, SD003, SD005, and SD012’s sulfate concentrations.

For reference, the outfall with the largest range of discharge flow volume is SD005, which has a long-term average flow of 9.6 MGD but is highly affected by precipitation events. Plant recycle water (for use in operations) is taken right before SD005 discharge and, depending on demand, there are times when the SD005 discharge is zero (0) MGD.

There are strict National Pollutant Discharge Elimination System (NPDES) regulations regarding the allowed concentration of sulfates in outfall water. Each outfall must continuously meet concentrations of 14 mg/L monthly average, and a 24 mg/L daily maximum. The facility may be subject to enforcement if noncompliant with the NPDES permit limits.

The Challenge

To meet these limits and in order to obtain relevant future permits, U.S. Steel is looking for novel approaches to reduce the existing levels of sulfate to below NPDES permit limits of 14 mg/L monthly average and 24 mg/L daily maximum at all water discharge outfalls at Keetac.

To-date, no technology, approach, treatment or mitigating method is currently installed in the facility or at any of the outfalls to reduce the sulfate concentrations.

Solvers are welcome to suggest biological, chemical, mechanical, or other innovative solutions that can address the sulfate levels in water discharged by U.S. Steel Keetac. The solution or method can be a combination of innovations or technologies.

The solution or method may be used at any one or multiple of the four outfalls. The solution may be applied at a single point in the process to affect all outfalls or the outfalls could be potentially combined to be affected by one solution. U.S. Steel is open to manipulating the outfalls to achieve a solution.

Solvers are encouraged to be creative in their approaches to meet the requirements, while also balancing the need for swift and effective solutions that can address U.S. Steel’s Challenge.

While there is no listed cost limit for solutions to meet at this stage, Solvers are encouraged to be conscious and communicative about potential set-up, operational, and maintenance costs in their solutions.
 

SOLUTION REQUIREMENTS

U.S. Steel is primarily interested in solutions with the potential to meet the following requirements:
 

Must have:

1. Effectively reduce sulfate concentrations at Keetac outfalls – continuously achieve average monthly concentration of 14 mg/L and a daily maximum concentration of 24 mg/L per NPDES permits.

This capability to reduce sulfate concentrations in discharge water from the facility must be continuous, not event-based.

2. Ability to operate in cold temperatures – with lows of −60 °F or −51.1 °C recorded in Minnesota winters in extreme cases.

Please note in your submission any potential area of your solution that may be negatively impacted by cold temperatures.

3. Minimized capital and operating costs of solution – U.S. Steel is looking for innovative approaches that can achieve the desired outcome while balancing operational and set-up costs. Please detail all costs in your submission.

4. Maintain networked effectiveness of the plant – in addressing the sulfate concentration Challenge, Solvers are encouraged to consider the wider operation of the plant and how to maintain, as far as possible, the ordinary operations involved in iron ore pellet production.

Additionally, U.S. Steel would be encouraged to see Solvers address the following nice-to-have criteria:

1. Limited increase in power consumption – it is desirable and encouraged that your solution does not dramatically increase the Keetac facility’s energy usage.
2. Limited number of treatment facilities – if your submission includes the use of sulfate treatment facilities, it would be desirable to limit the number (at least initially).
3. Minimized secondary environmental impacts – it is strongly encouraged that you detail any potential secondary environmental impacts or considerations involved in the installation or ongoing use of your solution.
    

Things to Avoid

Your solution must not cause future legacy sulfate mass issues (e.g. those proposing treatment and disposal of the mass must also consider where this could be disposed of effectively) or reduction in operation capacity or frequency of the plant (other than quick initial set-up).

Solutions with Technology Readiness Levels (TRLs) 1-6 are invited.

This Prize Challenge has the following features:
 

1. By taking part and submitting you are granting U.S. Steel a right to use (but not own) your submitted information, provided that U.S. Steel must determine the award winners within 45 days from the start of evaluation, otherwise U.S. Steel retains the right to use only Awarded solutions. You will receive notification.
2. There will be a guaranteed award pool of $25,000, with at least one award being $10,000 or more and no award being less than $2,500.
3. The award distribution will be determined after the theoretical evaluation of the proposal by U.S. Steel against the Solution Requirements.
4. U.S. Steel may also issue “Honorable Mention” recognitions for notable submissions that are not selected for monetary awards.  

YOUR SUBMISSION

Please login and register your interest, to complete the submission form.

The submitted proposals must be written in English and can include:

1. Participation type – you will first be asked to inform us how you are participating in this challenge, as a Solver (Individual) or Solver (Organization).
2. Solution Level - the Technology Readiness Level (TRL) of your solution.
3. Problem & Opportunity - highlight the innovation in your approach to the Problem, its point of difference, and the specific advantages/benefits this brings (up to 500 words).
4. Solution Overview - detail the features of your solution and how they address the SOLUTION REQUIREMENTS (500 words, there is space to add more in the summary field, and attach supporting data, diagrams, etc).
5. Experience - Expertise, use cases and skills you or your organization have in relation to your proposed solution.  (up to 500 words).
6. Solution Risks - any risks you see with your solution and how you would plan for this (up to 500 words).
7. Timeline, capability and costs - describe what you think is required to deliver the solution, estimated time and cost (up to 500 words).
8. Online References - provide links to any publications, articles or press releases of relevance (up to 500 words).

PARTICIPATION GUIDANCE

1. Submission Close Date: Submissions to this Challenge must be received by 11:59 PM (US Eastern Time) on May 13th, 2025.
2. Late submissions: Late submissions will not be considered.
3. Multiple submissions, 3 Maximum: In case of multiple submissions by the same Solver, only 3 submissions – the final 3 submitted – will be considered. Any other submissions will be deleted prior to evaluation.
4. Submission form and attachments: Your submission will be evaluated by the evaluation team first reviewing the information and content you have submitted at the submission form, with attachments used as additional context to your form submission. Submissions relying solely on attachments will receive less attention from the evaluation team.
5. Evaluation notification steps: After the Challenge submission close date, U.S. Steel will complete the review process and make a decision with regards to the winning solution(s) according to the timeline in the Challenge header. All Solvers who submit a proposal will be notified about the status of their submissions.
6. Use of AI: Please note that any submissions produced solely with generative AI are not of interest.
7. Learn more: Find out more about participation in Wazoku Crowd Challenges.