San Jose Project
Plymouth has partnered with the large Spanish company Sacyr and its wholly owned subsidiary Valoriza Mineria in an earn-in JV over a large, lithium-tin project (San Jose) in central Spain. Plymouth can earn up to 75% of San Jose by completing a Feasibility Study within 4 years (approximately A$6 million in spend).
The Project is located in the Extremadura region of Spain, this district is a rural area with a strong history and understanding of mining. Originally the project area was worked for tin in the early 20th century, more recently Lithium was discovered and an extensive development program was undertaken by the Spanish mining company, Tolsa. The deposit enjoys numerous benefits such as adjoining power and gas pipeline infrastructure in addition to the plentiful availability of acid and limestone.
A feasibility study completed in 1991 defined an open pit mining operation and a process flow sheet which produced lithium carbonate. The deposit is unique due to its extensive strike, width and surface outcrop that make it highly amenable to bulk, open-pit style mining methods. Lithium mineralisation extends from surface to in excess of 300m vertically and in excess of 500m along strike.
Figure 1: Aerial photograph of tenement holding and project area
Tolsa’s work on the deposit, between 1985 and 1991, included a comprehensive drilling program and wide ranging, detailed metallurgical work to produce a feasibility study that included a process flowsheet that could produce saleable lithium carbonate with good recoveries. Plymouth has purchased the historical data and reports produced by Tolsa. Plymouth is buiding on this knowledge base to fast track the development of the deposit.
Plymouth drilled a program of 10 holes (2 RC and 8 Diamond) for approximately 2,000m at the end of 2016 and in the first quarter of 2017. The drilling was designed to twin historical holes in order to provide maximum support for JORC resource calculations. The drilling and assay database for San Jose now comprises in excess of 52 holes for 10,000m of drilling including 3,500m of diamond drilling. The deposit is open at depth and along strike (Figure 2).
San Jose is a highly advanced lithium project which is hosted in lithium-mica minerals. The deposit has potential for high-grade zones with a reported Historical Foreign Estimation of Mineralisation of 14Mt @ 0.9% Li2O for 133kt contained lithium oxide (Li2O) at 0.75% Li2O cut off. This is hosted within a much larger global estimate of 468kt contained lithium oxide or 1.15Mt lithium carbonate equivalent.
A selection of significant intercepts from drilling at the deposit demonstrates the wide intercepts that characterise the mineralisation. Intercepts include;
- 45m @ 1.0% Li2O from surface hole MSJ-DD-0006
- 250m @ 1.0% Li2O from surface hole MSJ-DD-0003
- 142m @ 1.2% Li2O from 67m SJ-4C
- 52m @ 1.1% Li2O from 18m MSJ-DD-0004
Figure 2: San Jose long section showing historical (Tolsa) and all Plymouth drilling over grade contour. Section A-A’ as shown in collar plan
The long-section shown in Figure 2 demonstrates that the deposit has not been closed off by drilling and mineralisation remains open along strike and at depth and is host to very wide zones of mineralisation.
Figure 3: Collar plan showing location of long section line (figure 2) and all drillholes
The 1990 feasibility study conducted by Tolsa included extensive process test-work on the lithium mica at San Jose. This allowed a range of proven lithium process technologies to be tested. These included; calcining, acid leach, sulphate and water leach, alkali leach, gypsum and lime roast.
Outcomes of the historical studies include;
Beneficiation using gravimetric separation, flotation and high intensity magnetic separation – resulting in removal of 35% of waste with less than 1% loss of lithium
Preferred process routes to obtain Lithium Carbonate shortlisted Potassium Sulphate and Sulphuric acid pathways with both delivering strong recoveries of lithium as 99.5% lithium carbonate.
Figure 4: Simplified Acid process flowsheet
The 1993 summary of the feasibility study report stated “Sufficient tests have been carried out to be certain of the process in general, the recoveries of the metal and sulphuric acid and the commercial quality of the products obtained.” (Banco Exterior de Espana, BEX, 1993)
Plymouth is in the process of confirming the historic data to fast track the development of the San Jose project into production as soon as possible to take advantage of the European lithium battery demand.