Table of Contents

Milling & Refining

The first stage in transforming mined raw materials into powerful nuclear fuel is milling of the ore.

What is milling?

The Milling or Refining stage follows the uranium ore being extracted from the ground by mining.

In this stage, the ore is converted into yellowcake powder (U₃O₈) by chemical grinding, followed by a chemical process.

How are milling and refining carried out?

Step 1: Milling

First, uranium ore is crushed to a powder.

This step is crucial to the success of step two, as milling into a fine powder maximises the surface area on which chemical reactions can take place – crucial to the extraction of high grade nuclear fuel.

Step 2: Leaching

The product of milling, powdered ore, is dissolved in sulfuric acid (H₂SO₄) to form a solution that contains uranium and any impurities that were present.

This is then chemically purified, with the uranium precipitating out of solution in the form of concentrated triuranium octoxide.

Step 3: Calcination

After milling and leaching, the concentrated triuranium octoxide solution is dried and heated in a furnace to high temperatures (around 500–800°C), a process known as calcination.

Calcination results in the formation of high-purity yellowcake powder, U₃O₈, and is ready for conversion into nuclear fuel.

Where does milling take place?

Milling and refining usually takes place at or near to the mine.

Explore Further

Choose from the articles below to continue learning about nuclear.

Nuclear Waste – Arch Nemesis of the Nuclear Industry

Nuclear waste is the controversial by-product of nuclear reactors. It encompasses a variety of forms, each distinct in appearance and hazard level.