Accounts Payable Manager

ABOUT MARIANA MINERALS Mariana Minerals is a software-first, vertically integrated minerals company on a mission to supply the critical minerals powering modern energy, AI, and defense technologies. We’re reimagining the minerals supply chain by combining deep industry expertise with advanced software, automation, and data-driven decision-making. THE ROLE We are seeking an experienced Accounts Payable Manager to lead Mariana Minerals’ accounts payable operations and help build a scalable, technology-enabled procure-to-pay function. This position is responsible for ensuring the timely and accurate processing of supplier invoices, compliance with company purchasing policies and internal controls, and leading a high-performing AP team. The ideal candidate combines strong operational accounting experience with a continuous-improvement mindset and enjoys building efficient processes that leverage automation. As Mariana continues to grow, this role will play a key part in implementing best-in-class procure-to-pay practices, improving vendor relationships, strengthening internal controls, and supporting the company’s readiness for continued growth. This role will work closely with Procurement, Operations, Accounting, Treasury, FP&A, and business leaders across multiple operating locations. WHAT YOU’LL DO ACCOUNTS PAYABLE OPERATIONS - Supervise and assist in the daily processing of vendor invoices across multiple legal entities. - Ensure invoices are processed accurately, completely, and in accordance with company policies and payment terms. - Ensure three-way matching of purchase orders, goods receipts, and vendor invoices. - Review invoice coding for accuracy, including general ledger accounts, departments, projects, entities, and budget classes. - Manage invoice queues and ensure service-level expectations for invoice processing are achieved. - Coordinate weekly payment proposals with Treasury while supporting working-capital objectives and vendor relationships. - Monitor accounts payable aging and proactively VENDOR MANAGEMENT - Serve as the primary escalation point for vendor inquiries, account statements, and payment disputes. - Build strong relationships with key suppliers while ensuring consistent communication regarding payment status. - Coordinate the resolution of invoice discrepancies with Procurement and operational teams. - Oversee vendor onboarding documentation, including W-9 or W-8 forms, banking information, tax forms, certificates of insurance, and other required support. - Prepare and complete vendor credit applications to establish or expand supplier credit terms. - Assist in maintaining an accurate vendor master and support vendor due-diligence processes. INVOICE APPROVALS AND EXCEPTION MANAGEMENT - Supervise, coach, mentor, and develop Accounts Payable staff. - Establish performance expectations and monitor individual and team productivity, quality, and timeliness. - Conduct regular performance reviews and provide ongoing feedback and coaching. - Develop cross-training plans to ensure operational continuity and appropriate coverage. - Promote a culture of customer service, accountability, collaboration, and continuous improvement. TEAM LEADERSHIP - Supervise, coach, mentor, and develop Accounts Payable staff. - Establish performance expectations and monitor individual and team productivity, quality, and timeliness. - Conduct regular performance reviews and provide ongoing feedback and coaching. - Develop cross-training plans to ensure operational continuity and appropriate coverage. - Promote a culture of customer service, accountability, collaboration PROCESS IMPROVEMENT AND INTERNAL CONTROLS - Identify opportunities to automate invoice processing, approval workflows, and exception handling. - Support the implementation and optimization of AP automation tools, OCR technologies, and ERP workflows. - Develop and maintain standard operating procedures, desk procedures, and process documentation. - Ensure complian…