It is a great idea. The problem is often in the smelters, and other manufacturing processes. They are designed for certain element streams. For example we organ

It is a great idea. The problem is often in the smelters, and other manufacturing processes. They are designed for certain element streams. For example we organized delivery of 100,000+ tonnes of copper contaminated soil, and in another case lead contaminated soil to go by train to copper and lead smelters (processors.) So instead of paying to send to a hazardous waste treatment facility - where it would have been all buried, and would cost millions in disposal fees, the contaminated soil had value. Unfortunately, the value was so low, that it barely paid for hauling cost. (Still better than disposal cost, though.) The waste stream was too rich. The smelters had to dilute, and handle the waste streams separately. If it was a continuous process, then they could design a system to continuously handle it. In other words, this is possible, but as in most processing operations, it would require a comprehensive buy in, from all over the world, or across the USA, or across Europe, for example. With organising it could work. But everything is independent and dissociated. Similar to other problems we have, with electric power distribution, water management, etc.