EXHIBIT 99.1
JOINT FILING AGREEMENT
Each of the undersigned hereby agrees that this Amendment No. 24 to the statement on Schedule 13D is being filed with the United States Securities and Exchange Commission on behalf of each of the undersigned pursuant to Rule 13d-1(k) under the United States Securities Exchange Act of 1934, as amended.
Dated: April 7, 2020
| Glencore AG | ||
| By: | /s/ Stephan Huber | |
| Name: | Stephan Huber | |
| Title: | Officer | |
| By: | /s/ Martin Häring | |
| Name: | Martin Häring | |
| Title: | Director | |
| Glencore International AG | ||
| By: | /s/ John Burton | |
| Name: | John Burton | |
| Title: | Director | |
| By: | /s/ Peter Friedli | |
| Name: | Peter Friedli | |
| Title: | Officer | |
| Glencore plc | ||
| By: | /s/ John Burton | |
| Name: | John Burton | |
| Title: | Director | |
| By: | /s/ Peter Friedli | |
| Name: | Peter Friedli | |
| Title: | Officer | |
