URANIUM SOLUTION IN THE LODEVE MILL
6. IMPLEMENTATION OF THE PROJECT
After completion of the feasibility study and approval of the project two teams from the Research and Development Service (SEPA) of Coge"ma and SIMO managed the project, with the assistance of a French engineering company, Krebs S.A.
IAEA-TC-453.5/13 63
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64 LYAUDET et al.
IAEA-TC-453.5/13 65 TABLE III. ACTUAL CAPITAL COST
Items
1. Equipment
2. Modification and installation 3. Piping and valves
4. Electric equipment
The process document was finished in July 1983 and the order to Krebs was sent in September 1983. To complete the installation, the plant was shut down for three months (June to August 1983). The unit startup, like the whole plant, took place in September 1984, with the help of the SEPA, and without any significant difficulty.
Since October 1984, a gain on the operating costs has been made.
7. RESULTS2
7.1. Capital costs
Table III shows the actual capital costs incurred. The overall costs were only 2.85% above the estimate, i.e. F. Fr.12 600 000, estimated cost F. Fr.12 250 000 (US $1 575 000, estimated cost US $1 530 000).
The breakdown of the difference is as follows:
— Equipment costs; additional pumps and replacing a heat exchanger;
— Installation; relocation of the first precipitate tank and of the belt filter for peroxide;
2 Economic conditions as of September 1984.
66 LYAUDET et al.
TABLE IV. COMPARISON OF ACTUAL OPERATING COSTS BETWEEN THE PREVIOUS AND THE NEW PROCESS
Reagents and utilities Previous process (F. Fr./kg U) New process (F. Fr./kg U) Sulphuric acid (100%) 5.39 3.37
Sodium carbonate 1.46 — Lime 0.84 — Sodium hydroxide (100%) — 1.21 Hydrogen peroxide — 2.21 Clarcel — 0.21 Flocculants 0.93 0.54 Magnesia 0.99 — Propane 3.08 0.67 Electric power 2.25 2.38 Activated carbon 9.04 8.44 Penalty 1.21 —
Total 1 25.19 Total 2 19.03 Total 1 - Total 2 = F. Fr.6.16/kg U
— Civil engineering; repair of the concrete floor;
— Engineering studies were more expensive to cover the above three additional items.
The contingency estimate amply covered the increase of costs.
7.2. Operating costs
Operation of the new unit has been very satisfactory since the beginning. Sav-ings on the operating costs were made at the beginning of the second month.
The actual operating costs of the old and new processes are compared in Table IV. Actual savings of F. Fr.6.16 (US $0.77) per kg uranium were more than predicted (F. Fr.4.38, US $0.55) because of lower consumption of the reagents and electricity and also lower unit costs. Assuming a yearly production of 900 t U the actual savings in operating costs were F. Fr.5 545 000 (US $693 000) per year com-pared with the estimate in savings of F. Fr.4 200 000 (US $525 000).
IAEA-TC-453.5/13 67
7.3. Profitability
The profitability of the project is higher than estimated because of the greater savings in operating costs everywhere:
(a) Expenditure
— Capital costs of F. Fr.12 600 000 of which F. Fr.630 000 were paid in 1983.
— Manpower for one month shutdown, F. Fr.4 280 000.
(b) Savings
— Savings in operating costs for three months in 1984 amounted to F. Fr.l 660 000 (US $207 500).
— Savings of F. Fr.5 545 000 per year on operating costs.
— Savings (as estimated) F. Fr.270 000 per year on manpower and F. Fr. 110 000 per year on maintenance costs.
Based on the above, profit on the project can be calculated in terms of 2.6 years.
— An adjusted pay-back time of 2.8 years (discount rate of 10%) resulted in an internal profit rate of 35 %.
8. CONCLUSIONS
From a technical and planning point of view the project was very successful.
An important contribution to the success was the involvement of the engineers in all stages of the project and especially the startup.
From the economic point of view results were better than expected. The experience gained shows that in the case of a significant modification of an existing unit the feasibility study must consider a contingency rate as high as 20% of the over-all costs.
REFERENCE
[1] BODU, R., et al., "L'usine de Lodeve: Un proc&Je' alcalin complexe pour un mineral d'uranium complexe", Advances in Uranium Ore Processing and Recovery from Non-Conventional Resources (Proc. Tech. Comm. Mtg. Vienna, 1983), IAEA, Vienna (1985) 131-168.
DISCUSSION
F.-K. FELDMANN: What is the uranium concentration going to the solvent extraction system?
P. MICHEL: In the Lodeve mill, there is no solvent extraction. The pregnant solution contains about 2.8 g/L uranium.
68 LYAUDET et al.
F.-K. FELDMANN: Why do you precipitate the zirconium? Is there a com-mercial reason?
P. MICHEL: We remove zirconium because it was present as an impurity in the concentrate and we were being penalized for that. Almost all the zirconium is precipitated with the uranium when using hydrogen peroxide. We redissolve the precipitate at a pH of about 3. Zirconium remains as a solid and is removed by filter-ing in precoat filters. Only a small part of the zirconium in the ore is dissolved, but it is enough to require a purification step.
H.J. STEINER: Which is the zirconium bearing mineral?
G. LYAUDET: Zirconium is contained in complex silicates associated with pitchblende.
H.J. STEINER: Why was the zirconium not detected during the initial test work? Did you not have a good sample or did you simply not pay attention to the problem?
P. MICHEL: We did not have a good sample. As I said in the paper, Lodeve is a good illustration of ore variability. Lodeve is in fact not a single ore body, but many small ore bodies in the same area. There are large differences between one place and another, sometimes within a few metres. During the operation of the pilot plant we checked the levels of zirconium in many of the process stages and the levels were low. But the ore sample we used was not the same as the ore we used during the first and second years of industrial operation. This was not the fault of the pilot plant people.
Y. VOLKMAN: What is the concentration of sodium carbonate in the solution that is fed to the process?
P. MICHEL: It is about 16 g/L.
Y. VOLKMAN: Do you recover the carbon dioxide which is evolved upon destruction of the carbonate?
P. MICHEL: No. We do not.
IAEA-TC-453.5/1
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