TORONTO, ONTARIO--(Marketwire - Sept. 4, 2012) - Detour Gold Corporation (News - Market indicators) ("Detour Gold" or the "Company") is pleased to announce an updated open pit mine production plan for its 100% owned Detour Lake gold mine in northeastern Ontario. The updated mine production plan supports a 21.5-year operating life with the current mineral reserve of 15.6 million ounces of gold (470 million tonnes grading 1.03 g/t Au). Project construction is progressing very well, having reached the 87% completion mark at the end of August 2012. Detour Lake remains on budget and on schedule for gold production to start in the first quarter of 2013. All figures are in Canadian dollars except where noted.

A National Instrument 43‐101 ("NI 43‐101") technical report for the updated mine plan will be filed within 45 days on SEDAR (www.sedar.com) and on the Company's website (www.detourgold.com).

Highlights

• Proven and probable open pit reserves of 15.6 million ounces contained gold
• Reduced strip ratio (waste to ore) to 3.7:1
• 21.5 years life of mine (LOM) at mill throughput ranging from 55,000 to 61,000 tpd
• Average annual gold production of approximately 657,000 ounces
• Average LOM cash operating costs of $710/oz and total cash costs of $749/oz
• 2013 gold production forecast between 350,000 and 400,000 ounces
• On schedule to start gold production in Q1 2013

"We are very pleased with this updated life of mine production plan and the detailed work we have done. Based on a production startup of January 2013 and assuming commercial production is achieved in July, the mine is expected to produce up to 400,000 ounces of gold in 2013," commented Gerald Panneton, President and CEO of Detour Gold. "I would like to take this occasion to thank the entire Detour Gold team for their dedication and hard work. Our team is ready to start commissioning in the fourth quarter, which will be followed by the commencement of operations. We have succeeded in recruiting a very talented group of individuals who are playing an integral role in achieving our near-term objective of becoming a leading mid-tier gold producer and a premier investment opportunity. Over the first three years of operation including 2013, we estimate the project to generate over a $1 billion of operational cash flow. With average annual gold production projected at 657,000 ounces, the Detour Lake mine will be among the largest gold operations in North America."

Project Assumptions and Parameters

Detour Lake Mineral Reserves

Detour Gold used the 2011 year-end mineral reserves (refer to press release January 25, 2012) to develop the new life of mine (LOM) production plan. The 2011 year-end mineral reserves were estimated in MineSight with the kriged block grades that included an estimated dilution of 11.7%. The proven and probable reserves totaled 15.6 million ounces, after using a 95% mining recovery rate and an additional mining dilution of 3.8%.

Mining and Production

Total gold production over LOM is estimated to be 14.1 million ounces, averaging 657,000 ounces per year (plus 200,000 ounces of silver). The LOM waste to ore ratio is estimated at 3.7 to 1.

The Company is planning to stockpile material grading between 0.3 to 0.5 g/t over the life of mine (approximately 240 Mt averaging 0.39 g/t Au), which could potentially be processed during the LOM if the Company proceeds with an expansion of the processing plant facilities.

Summary of the annual mine production plan is outlined below.

As part of the operation readiness plan, the pre-stripping operation is well underway in the Calcite Zone (western portion) of the Detour Lake deposit. The Company has started its mining activities in this wide mineralized zone (50 to 150 metres wide), with a lower grade (0.8 to 0.9 g/t) than the average grade of the mineral reserves, because it is wider and easier to provide ore production in the ramp up year of the mine to sustain the mine throughput. The plan is to stockpile 2.3 million tonnes of ore at an average grade of 0.85 g/t by year-end 2012. This ore will be available if commissioning proceeds ahead of schedule. At the end of August 2012, the Company had mined over 14 million tonnes of material.

Conventional open pit mining methods will be used to mine the Detour Lake deposit utilizing an initial fleet of 20 haul trucks (CAT 795F - 320 tonnes), 2 hydraulic shovels (CAT6060 - 28/34m³), 2 electric rope shovels (CAT7495 - 48m³), 9 drills and various ancillary equipment to support the mining operation. The fleet will ramp up to 41 at the peak of the mine operation. The open pit design incorporates 12 metre high benches with a 35 metre wide main haul road at a maximum grade of 10%.

Processing Plant - Two independent grinding lines

The processing plant under construction is a conventional gravity, cyanidation and carbon-in-pulp facility initially operating at 55,000 tpd and ramping-up to 61,000 tpd in 2015. The assumed availability of the plant is 92% for the first few years and ramping up to 94% in year 3. The grinding circuit consists of two parallel lines, each having one twin pinion semi-autogenous (SAG) mill (36'X20') and one twin pinion ball mill (26'X40.5'). These four mills are all equipped with a pair of 7,500 kW variable speed drive motors. The crushing capacity is enhanced with inclusion of a larger gyratory crusher (60"X113" HD equipped with 1,000 kW) and the addition of a secondary crushing circuit (2X750 kW crushers). This system is complemented with additional crushing capacity in the pebble crushing circuit (2X750 kW crushers).

The overall gold recovery is estimated at 91.0% with silver recovery estimated at 48%.

Operating Costs

Cash operating costs over the LOM are projected to average $710/oz. Total cash costs (after royalty and silver credits) are anticipated to average $749/oz.

The updated cash operating costs are based on current market prices for consumables and all other mine benchmarking such as current costs at the Project site. The following assumptions have been made: electricity - $0.065/kWhr and diesel fuel - $0.92/litre.

Commercial Production

The Company plans to commence gold production in January 2013 starting with one grinding line (1 SAG + 1 ball mill). Commercial production is expected to be declared on the first day of the calendar month following the mine having operated for a period of 60 consecutive days at an average of 75% or more of the designed production capacity (55,000 tpd x 75% = 41,250 tpd). Pre-commercial gold production is estimated at approximately 144,000 ounces and commercial gold production is estimated at approximately 250,000 ounces (excluding the 12,715 ounces locked in the circuit load).

2013 Guidance

Management's guidance is as follows:

• Gold production ranging between 350,000 and 400,000 ounces of gold
• Total cash costs of between $800/oz and $900/oz (to be reported after commercial production is declared)
• Estimated 2013 sustaining capital of approximately $180 million, mainly for construction of the second cell of the tailings facilities and additional mining fleet costs

Capital Costs Update

The estimated pre-production capital costs of $1.45 billion remain unchanged. As of July 31, 2012, the Company had spent $1.07 billion and had approximately $462 million in cash and short-term investments, sufficient to fully finance the remaining project expenditures ($380 million). As part of our risk management strategy, the Company is in the process of obtaining a $100 million secured credit facility to provide additional financial flexibility and working capital during the initial mine ramp-up period. As well, the Company is putting in place a $50 million credit facility that will allow its letters of credit to be uncollateralized.

Sustaining capital expenditures over the operation's mine life are estimated at $1.2 billion.

The economic cash flow model is based on a gold price of US$1,600/oz in 2013, US$1,500/oz in 2014, US$1,400/oz in 2015 and then decreasing to US$1,200/oz after 2015, resulting in estimated undiscounted pre-tax operating LOM cash flow of US$4.3 billion and after capital and taxes net cash flow of US$3.0 billion.

Qualified Persons

A NI 43-101 compliant Technical Report will be filed on the Company's website and on SEDAR within 45 days. The report is being prepared by leading independent industry consultants, all Qualified Persons (QP) under National Instrument 43-101, with the collaboration of the Detour Gold technical group. The QPs have reviewed and approved the content of this news release. The following consultants participated in the study:

• BBA Inc., under the direction of André Allaire, Eng., Vice-President, Markets - Mining and Metals (overall report preparation, mineral processing and infrastructures, capital and operating cost estimates and overall financial analysis) and Patrice Live, Eng., Mining Manager (mineral reserves, open-pit optimization and engineered pit design, mine planning, and mining capital and operating cost estimates)
• SGS Canada Inc., under the direction of Michel Dagbert, Eng., Senior Geostatistician (mineral resources) and Maxime Dupéré, P.Geo., Senior Geologist (geology, quality assurance/quality control, and data verification)

Conference Call

Detour Gold will hold a conference call today at 10:00 AM EDT where senior management will discuss this press release and respond to questions from analysts and investors. To join the call:

• By phone toll free in Canada and the United states 1-866-226-1792

• By phone International 416-340-2216

• To listen online, go to www.detourgold.com and click on the "Conference Call Audio Webcast, September 4, 2012" link on home page

The conference call will be recorded and playback of the call will be available after the event by dialing toll free in Canada and the United States 1-800-408-3053, or internationally 905-694-9451, pass code 6848711 (available up to September 18, 2012).

Forward-Looking Information

This press release contains certain forward-looking information as defined in applicable securities laws (referred to herein as "forward-looking statements"). Specifically, this press release contains forward-looking statements regarding reserve and resource estimates, ore grade, the expected mine life, anticipated gold production, gold recovery, the commencement of production, operating costs, and capital costs. Forward-looking statements involve known and unknown risks, uncertainties and other factors which are beyond Detour Gold's ability to predict or control and may cause Detour Gold's actual results, performance or achievements to be materially different from any of its future results, performance or achievements expressed or implied by forward-looking statements. These risks, uncertainties and other factors include, but are not limited to, gold price volatility, changes in debt and equity markets, the uncertainties involved in interpreting geological data, increases in costs, environmental compliance and changes in environmental legislation and regulation, interest rate and exchange rate fluctuations, general economic conditions and other risks involved in the gold exploration and development industry, as well as those risk factors discussed in the section entitled "Description of Business - Risk Factors" in Detour Gold's 2009 annual information form.

Such forward-looking statements are also based on a number of assumptions which may prove to be incorrect, including, but not limited to, assumptions about the following: the availability of financing for exploration and development activities; the estimated timeline for the development of the Detour Lake gold project; the supply and demand for, and the level and volatility of the price of, gold; the accuracy of reserve and resource estimates and the assumptions on which the reserve and resource estimates are based; the receipt of necessary permits; market competition; ongoing relations with employees and impacted communities; and general business and economic conditions. In addition, the feasibility study uses an estimate of gold price based on an approximate three-year average. The operating and capital costs in the feasibility study were developed to be reasonable estimates within industry benchmarks. There is no certainty that the results of the feasibility study will ever be realized. Should one or more of the risks or uncertainties involved in forward-looking statements relating to the feasibility study materialize, or should the assumptions underlying the feasibility study prove incorrect, actual results of the feasibility study may vary materially from those anticipated, believed, estimated or expected. Accordingly, readers should not place undue reliance on forward-looking statements. Detour Gold undertakes no obligation to update publicly or otherwise revise any forward-looking statements contained herein whether as a result of new information or future events or otherwise, except as may be required by law.

Information Concerning Estimates of Mineral Reserves and Resources

The mineral reserve and resource estimates reported in this press release were prepared in accordance with Canadian National Instrument 43-101Standards of Disclosure for Mineral Projects ("NI 43-101"), as required by Canadian securities regulatory authorities. For United States reporting purposes, the United States Securities and Exchange Commission ("SEC") applies different standards in order to classify mineralization as a reserve. In particular, while the terms "measured," "indicated" and "inferred" mineral resources are required pursuant to NI 43-101, the SEC does not recognize such terms. Canadian standards differ significantly from the requirements of the SEC. Investors are cautioned not to assume that any part or all of the mineral deposits in these categories constitute or will ever be converted into reserves. In addition, "inferred" mineral resources have a great amount of uncertainty as to their existence and great uncertainty as to their economic and legal feasibility. It cannot be assumed that all or any part of an inferred mineral resource will ever be upgraded to a higher category. Under Canadian securities laws, issuers must not make any disclosure of results of an economic analysis that includes inferred mineral resources, except in rare cases.