TORONTO, ONTARIO--(MARKET WIRE)--May 27, 2008 -- Macusani Yellowcake Inc. ("Macusani")(CDNX:YEL.V - News) -

Peter Hooper, President of Macusani stated: "This testing demonstrates that the concept of a low cost heap leach mine is realistic."

Two samples of uranium ore from two distinct mineralised areas located in Colibri II-III concession, Macusani plateau, underwent column acid leaching tests. The first sample ran ahead grade of 509ppm U (average grade), and the second samples ran at 75ppm U (low grade).

The metallurgical testwork has been managed by Ing. Jose Mallqui (MSc) from TECMMINES who was employed in a consultancy basis by Macusani Yellowcake Inc. through its Peruvian subsidiary, Global Gold. The tests were run at Colibri's refinery facilities in Lima, and the samples were analysed by CIMM Peru.

The four column leach tests have been run in static column of 7 inches with the objective to determine the operational parameters of the uranium leaching in heaps of uranium ore; such as, final uranium leaching (%), leaching times expressed in days, sulphuric acid consumption (kg/t), acid fluid flow rate (m3/ton).

Two types of tests were run: During the first series the ore was loaded in columns and subsequently leached with sulphuric acid at 15g/l, and in the second series the uranium ore was pre-treated (soaked) within a concentrated sulphuric acid solution at 60g/l to the level of reaching a moisture of roughly 9-10% and subsequently the pre-soaked sample underwent the same leaching conditions as samples from series 1.

The test conditions are described below:

 

Grain size:                              100% passing 2 inches
Weight of dry ore (un-treated):             approx. 92 - 95 kg
Weight of dry ore (pre-soaked):           approx. 85 - 87.5 kg
Leaching solution flow rate:                          8 l/h/m2
Acid concentration in solution:                         15 g/l
pH:                                                less than 2
Flow type:                                            dripping
Leaching type:                                    open circuit
Pre-treatment 1st series:                     no pre-treatment
Pre-treatment 2nd series:                         acid soaking
Pre-treatment solution:                        H2SO4 at 50 g/l
Pre-treatment time:                                   24 hours
Pre-soaked material final moisture:             10.87 - 11.00%
First day of the test:                           17 March 2008

The metallurgical recovery results obtained during the column leaching tests (1st and 2nd series) are shown in the table below:

 

---------------------------------------------------------------------
                                      Acid consumption    Fluid flor
                 Ore type      % U               (kg/t)        (m3/t)
---------------------------------------------------------------------
1st series    Zone 2 (75p)   84.37               14.62         1.525
           ----------------------------------------------------------
Un-treated   Zone 1 (509p)   98.58               14.48         1.531
---------------------------------------------------------------------
2nd series   Zone 1 (509p)   77.32               17.05         1.708
           ----------------------------------------------------------
Pre-soaked    Zone 2 (75p)   69.50               16.41         1.599
---------------------------------------------------------------------

The kynetic curves showing the uranium leaching in the acid solution over on month in columns (un-treated against pre-soaked ore) for both ore types (of low and medium-grade uranium) are displayed below:

To view a graph of the Uranium solubility zone 1, please visit the link below:

http://media3.marketwire.com/docs/yelzone1.pdf

 

URANIUM ZONE 1
Solution               equals  501.387  g/t
Residue                equals     7.20  g/t
Analytical head grade  equals  508.587  g/t
Assayed head grade     equals  509.000  g/t
Recovery               equals    98.58  %
H2SO4 consumption      equals    14.48  Kg/t

URANIUM ZONE 2
Solution               equals   23.911  g/t
Residue                equals     4.43  g/t
Analytical head grade  equals   28.341  g/t
Assayed head grade     equals   75.000  g/t
Recovery               equals    84.37  %
H2SO4 consumption      equals    14.62  Kg/t

To view a graph of the Uranium solubility zone 2, please visit the link below:

http://media3.marketwire.com/docs/yelzone2.pdf

The kynetic curves displaying the uranium leaching in columns, for each mineralised zone demonstrate:

The pre-soaking in acid allows a faster response to leaching during the first days of acid leaching, however it does not allow a higher final recovery after one month of testing. In reality, after 18 days of leaching for the average-grade uranium ore (509ppm U) and after 13 days for the low-grade uranium ore (75ppm U) the leaching of the un-treated ore reaches a faster pace when compared with the pre-soaked ore. For both ore types the final recovery was higher for the un-treated ore than for the pre-soaked ore.

The final recovery after 31 days in columns of the low-grade ore was 84.37% and 98.58% for the average-grade uranium ore. The pre-soaking of the ore does not improve the leaching cycle nor does improve the kynetic of the uranium solubility in the acid leaching solution.

The final uranium recovery reached a plateau extraction zone after 20-25 days for both ore types. The sulphuric acid consumption was much lower than in the bottle roll tests published by Macusani Yellowacke during March 2008, dropping from 28.5kg/t to about 14kg/t. The lower acid consumption is probably due to a lower exposure to acid of the ore exposed in columns than in the bottle roll tests, which does not allow other Uranium accompanying elements to become soluble in the acid.

The high uranium solubility reached during the test run on ore from zone 1 (average-grade uranium ore of 509ppm U) is similar to the solubility reached by the same sample in bottle roll tests that further demonstrates that the ore is porous and easy to percolate by acid leaching solutions. The lower-grade ore exhibits a lower recovery of 84% but still higher than the results obtained in bottle roll tests one month ago.

Further tests will be run in the next months in order to improve the solubility of the uranium ores of lower grade, where mineralisation is usually disseminated. In this case the next phase of metallurgical tests will emphasize on the relationship between grain size and uranium solubility in column tests.

Considering that during these first column tests the grain size of the particles was 100% passing 2 inches, which is relatively coarse, it is expected that a finer grain size of 1 inch or 3/4 of an inch will further improve the recovery of the uranium ores of lower grade.

The next phase of metallurgical tests will attempt to cover the entire strike length of the drilled mineralisation exposed to date by drilling (almost 2 km along strike) in order to obtain a more reliable picture of the leaching parameters of the uranium ore exposed at Macusani. In excess of 30 new metallurgical samples from the entire area of the Colibri II-III concession, in corroboration with the drilling data are prepared at present for new metallurgical tests in leaching columns as well as bottle roll tests.

About Macusani Yellowcake Inc.

Macusani controls over 20,000 hectares (2,000 km2) of mineral properties on the Macusani plateau in Peru.

There are 24,296,285 common shares of Macusani Yellowcake Inc. outstanding, 32,876,260 common shares, fully diluted.

The TSX Venture Exchange does not accept responsibility for the adequacy or accuracy of this release.

     Contacts:
     Macusani Yellowcake Inc.
     Peter Hooper
     President
     (416) 360-3402
     Email: peterhooper2@aol.com
     Website: http://www.macusaniyellowcake.com